From a8923dc6595785ee82e827ff5702440cbf3e3598 Mon Sep 17 00:00:00 2001
From: Belin Wu <belinwu@qq.com>
Date: Fri, 25 Jan 2019 14:04:44 +0800
Subject: [PATCH 1/3] Support async differ, etc

- Recode to two library modules: core and paging.
- Let `ModularAdapter` generalized.
- Intro `AsyncDiffer` and its implementations: `NonAsyncDiffer`, `ListAsyncDiffer` and `PagedAsyncDiffer`.
---
 build.gradle                                  |   5 +-
 {library => core}/.gitignore                  |   0
 {library => core}/build.gradle                |  43 +++---
 {library => core}/proguard-rules.pro          |   0
 .../modapter/ExampleInstrumentedTest.java     |   0
 .../src/main/AndroidManifest.xml              |   2 +-
 .../com/samelody/modapter/AbstractItem.java   |   0
 .../samelody/modapter/AdapterDelegate.java    |  69 ++++++----
 .../com/samelody/modapter/AdapterItem.java    |   0
 .../com/samelody/modapter/ItemManager.java    |  50 ++++---
 .../com/samelody/modapter/ItemMetadata.java   |   0
 .../com/samelody/modapter/ItemViewHolder.java |   0
 .../com/samelody/modapter/ModularAdapter.java | 125 ++++++++++++++++++
 .../samelody/modapter/differ/AsyncDiffer.java |  22 +++
 .../modapter/differ/ListAsyncDiffer.java      |  58 ++++++++
 .../modapter/differ/NonAsyncDiffer.java       |  48 +++++++
 .../src/main/res/values/strings.xml           |   0
 .../samelody/modapter/ExampleUnitTest.java    |   0
 .../com/samelody/modapter/ModularAdapter.java |  68 ----------
 paging/.gitignore                             |   2 +
 paging/build.gradle                           |  53 ++++++++
 paging/proguard-rules.pro                     |  21 +++
 .../modapter/ExampleInstrumentedTest.java     |  26 ++++
 paging/src/main/AndroidManifest.xml           |   2 +
 .../modapter/differ/PagedAsyncDiffer.java     |  66 +++++++++
 .../com/samelody/modapter/package-info.java   |   1 +
 paging/src/main/res/values/strings.xml        |   3 +
 .../samelody/modapter/ExampleUnitTest.java    |  17 +++
 sample/build.gradle                           |   7 +-
 .../samples/modapter/MainActivity.java        |  26 ++--
 settings.gradle                               |   2 +-
 31 files changed, 562 insertions(+), 154 deletions(-)
 rename {library => core}/.gitignore (100%)
 rename {library => core}/build.gradle (89%)
 rename {library => core}/proguard-rules.pro (100%)
 rename {library => core}/src/androidTest/java/com/samelody/modapter/ExampleInstrumentedTest.java (100%)
 rename {library => core}/src/main/AndroidManifest.xml (61%)
 rename {library => core}/src/main/java/com/samelody/modapter/AbstractItem.java (100%)
 rename {library => core}/src/main/java/com/samelody/modapter/AdapterDelegate.java (76%)
 mode change 100755 => 100644
 rename {library => core}/src/main/java/com/samelody/modapter/AdapterItem.java (100%)
 rename {library => core}/src/main/java/com/samelody/modapter/ItemManager.java (60%)
 rename {library => core}/src/main/java/com/samelody/modapter/ItemMetadata.java (100%)
 rename {library => core}/src/main/java/com/samelody/modapter/ItemViewHolder.java (100%)
 mode change 100755 => 100644
 create mode 100644 core/src/main/java/com/samelody/modapter/ModularAdapter.java
 create mode 100644 core/src/main/java/com/samelody/modapter/differ/AsyncDiffer.java
 create mode 100644 core/src/main/java/com/samelody/modapter/differ/ListAsyncDiffer.java
 create mode 100644 core/src/main/java/com/samelody/modapter/differ/NonAsyncDiffer.java
 rename {library => core}/src/main/res/values/strings.xml (100%)
 rename {library => core}/src/test/java/com/samelody/modapter/ExampleUnitTest.java (100%)
 delete mode 100644 library/src/main/java/com/samelody/modapter/ModularAdapter.java
 create mode 100644 paging/.gitignore
 create mode 100644 paging/build.gradle
 create mode 100644 paging/proguard-rules.pro
 create mode 100644 paging/src/androidTest/java/com/samelody/modapter/ExampleInstrumentedTest.java
 create mode 100644 paging/src/main/AndroidManifest.xml
 create mode 100644 paging/src/main/java/com/samelody/modapter/differ/PagedAsyncDiffer.java
 create mode 100644 paging/src/main/java/com/samelody/modapter/package-info.java
 create mode 100644 paging/src/main/res/values/strings.xml
 create mode 100644 paging/src/test/java/com/samelody/modapter/ExampleUnitTest.java

diff --git a/build.gradle b/build.gradle
index e67f240..302e278 100644
--- a/build.gradle
+++ b/build.gradle
@@ -4,16 +4,13 @@ buildscript {
     def deps = [:]
     ext.deps = deps
 
-    deps.libVersionCode = 1
-    deps.libVersionName = "0.1.0"
-    deps.demoVersionCode = 1
-    deps.demoVersionName = "0.1.0"
     deps.compileSdk = 28
     deps.targetSdk = 28
     deps.minSdk = 15
 
     deps.appcompat = "com.android.support:appcompat-v7:28.0.0"
     deps.recyclerview = "com.android.support:recyclerview-v7:28.0.0"
+    deps.paging = "android.arch.paging:runtime:1.0.1"
     deps.constraintlayout = "com.android.support.constraint:constraint-layout:1.1.3"
     deps.junit = "junit:junit:4.12"
     deps.test = "com.android.support.test:runner:1.0.2"
diff --git a/library/.gitignore b/core/.gitignore
similarity index 100%
rename from library/.gitignore
rename to core/.gitignore
diff --git a/library/build.gradle b/core/build.gradle
similarity index 89%
rename from library/build.gradle
rename to core/build.gradle
index ab178e7..6bbf8ed 100644
--- a/library/build.gradle
+++ b/core/build.gradle
@@ -1,12 +1,32 @@
 apply plugin: 'com.android.library'
 
+ext.pubspec = [:]
+
+pubspec.packaging = 'aar'
+pubspec.groupId = 'com.samelody.modapter'
+pubspec.artifactId = 'modapter-core'
+pubspec.repo = 'maven'
+pubspec.name = 'Modapter'
+pubspec.description = 'Modular adapter for Android RecyclerView.'
+pubspec.version = "0.2.0-alpha1"
+pubspec.versionCode = 2
+pubspec.url = 'https://github.com/samelody/modapter'
+pubspec.gitUrl = 'https://github.com/samelody/modapter.git'
+pubspec.issueUrl = 'https://github.com/samelody/modapter/issues'
+pubspec.developerId = 'belinwu'
+pubspec.developerName = 'Belin Wu'
+pubspec.developerEmail = 'belinwu@qq.com'
+pubspec.licenseName = 'Apache License 2.0'
+pubspec.licenseUrl = 'https://raw.githubusercontent.com/samelody/modapter/master/LICENSE'
+pubspec.licenses = ["Apache-2.0"]
+
 android {
     compileSdkVersion deps.compileSdk
     defaultConfig {
         minSdkVersion deps.minSdk
         targetSdkVersion deps.targetSdk
-        versionCode deps.libVersionCode
-        versionName deps.libVersionName
+        versionCode pubspec.versionCode
+        versionName pubspec.version
         testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
     }
 
@@ -29,23 +49,4 @@ dependencies {
     androidTestImplementation deps.espresso
 }
 
-ext.pubspec = [:]
-
-pubspec.packaging = 'aar'
-pubspec.groupId = 'com.samelody.modapter'
-pubspec.artifactId = 'modapter'
-pubspec.repo = 'maven'
-pubspec.name = 'Modapter'
-pubspec.description = 'Modular adapter for Android RecyclerView.'
-pubspec.version = deps.libVersionName
-pubspec.url = 'https://github.com/samelody/modapter'
-pubspec.gitUrl = 'https://github.com/samelody/modapter.git'
-pubspec.issueUrl = 'https://github.com/samelody/modapter/issues'
-pubspec.developerId = 'belinwu'
-pubspec.developerName = 'Belin Wu'
-pubspec.developerEmail = 'belinwu@qq.com'
-pubspec.licenseName = 'Apache License 2.0'
-pubspec.licenseUrl = 'https://raw.githubusercontent.com/samelody/modapter/master/LICENSE'
-pubspec.licenses = ["Apache-2.0"]
-
 apply from: "https://raw.githubusercontent.com/samelody/pubman/master/pub.gradle"
\ No newline at end of file
diff --git a/library/proguard-rules.pro b/core/proguard-rules.pro
similarity index 100%
rename from library/proguard-rules.pro
rename to core/proguard-rules.pro
diff --git a/library/src/androidTest/java/com/samelody/modapter/ExampleInstrumentedTest.java b/core/src/androidTest/java/com/samelody/modapter/ExampleInstrumentedTest.java
similarity index 100%
rename from library/src/androidTest/java/com/samelody/modapter/ExampleInstrumentedTest.java
rename to core/src/androidTest/java/com/samelody/modapter/ExampleInstrumentedTest.java
diff --git a/library/src/main/AndroidManifest.xml b/core/src/main/AndroidManifest.xml
similarity index 61%
rename from library/src/main/AndroidManifest.xml
rename to core/src/main/AndroidManifest.xml
index eba1a0e..592e9cf 100644
--- a/library/src/main/AndroidManifest.xml
+++ b/core/src/main/AndroidManifest.xml
@@ -1,2 +1,2 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
-    package="com.samelody.modapter" />
+    package="com.samelody.modapter.core" />
diff --git a/library/src/main/java/com/samelody/modapter/AbstractItem.java b/core/src/main/java/com/samelody/modapter/AbstractItem.java
similarity index 100%
rename from library/src/main/java/com/samelody/modapter/AbstractItem.java
rename to core/src/main/java/com/samelody/modapter/AbstractItem.java
diff --git a/library/src/main/java/com/samelody/modapter/AdapterDelegate.java b/core/src/main/java/com/samelody/modapter/AdapterDelegate.java
old mode 100755
new mode 100644
similarity index 76%
rename from library/src/main/java/com/samelody/modapter/AdapterDelegate.java
rename to core/src/main/java/com/samelody/modapter/AdapterDelegate.java
index cf3f5fc..8263bc7
--- a/library/src/main/java/com/samelody/modapter/AdapterDelegate.java
+++ b/core/src/main/java/com/samelody/modapter/AdapterDelegate.java
@@ -8,19 +8,19 @@
 import android.view.View;
 import android.view.ViewGroup;
 
+import com.samelody.modapter.differ.AsyncDiffer;
+import com.samelody.modapter.differ.NonAsyncDiffer;
+
 import java.lang.reflect.InvocationTargetException;
-import java.util.Collections;
 import java.util.List;
 
-import static java.util.Collections.emptyList;
-
 
 /**
  * The delegated implementation of modular adapter.
  *
  * @author Belin Wu
  */
-public final class AdapterDelegate implements ItemManager {
+public final class AdapterDelegate<E extends AdapterItem> implements ItemManager<E> {
 
     /**
      * The item metadata registry.
@@ -28,10 +28,24 @@ public final class AdapterDelegate implements ItemManager {
     private SparseArray<ItemMetadata> registry = new SparseArray<>();
 
     /**
-     * The list of items.
+     * A async differ.
      */
-    @NonNull
-    private List<? extends AdapterItem> list = emptyList();
+    private AsyncDiffer<E> differ;
+
+    public AdapterDelegate() {
+        this(new NonAsyncDiffer<E>());
+    }
+
+    public AdapterDelegate(AsyncDiffer<E> differ) {
+        checkDiffer(differ);
+        this.differ = differ;
+    }
+
+    private void checkDiffer(AsyncDiffer<E> differ) {
+        if (differ == null) {
+            throw new IllegalArgumentException("differ argument must not be null");
+        }
+    }
 
     /**
      * Gets item count.
@@ -39,34 +53,37 @@ public final class AdapterDelegate implements ItemManager {
      * @return The item count.
      */
     public int getItemCount() {
-        return list.size();
+        return differ.getItemCount();
     }
 
-    /**
-     * {@inheritDoc}
-     */
-    @Nullable
-    @SuppressWarnings("unchecked")
     @Override
-    public <T extends AdapterItem> T getItem(int position) {
-        if (position < 0 || position >= list.size()) {
-            return null;
-        }
-        return (T) list.get(position);
+    public ItemManager<E> setDiffer(AsyncDiffer<E> differ) {
+        checkDiffer(differ);
+        this.differ = differ;
+        return this;
     }
 
-    /**
-     * {@inheritDoc}
-     */
+    @NonNull
     @Override
-    public ItemManager setList(List<? extends AdapterItem> list) {
-        this.list = list == null ? Collections.<AdapterItem>emptyList() : list;
+    public ItemManager<E> submitList(List<? extends E> list) {
+        differ.submitList(list);
         return this;
     }
 
+    @Override
+    public List<E> getCurrentList() {
+        return differ.getCurrentList();
+    }
+
+    @Nullable
+    @Override
+    public E getItem(int position) {
+        return differ.getItem(position);
+    }
+
     @NonNull
     @Override
-    public <T extends ViewHolder> ItemManager register(int layoutId, Class<T> holderClass) {
+    public ItemManager<E> register(int layoutId, Class<? extends ViewHolder> holderClass) {
         ItemMetadata metadata = new ItemMetadata();
         metadata.setLayoutId(layoutId);
         metadata.setHolderClass(holderClass);
@@ -76,7 +93,7 @@ public <T extends ViewHolder> ItemManager register(int layoutId, Class<T> holder
 
     @NonNull
     @Override
-    public ItemManager register(ItemMetadata metadata) {
+    public ItemManager<E> register(ItemMetadata metadata) {
         if (metadata != null) {
             registry.put(metadata.getLayoutId(), metadata);
         }
@@ -85,7 +102,7 @@ public ItemManager register(ItemMetadata metadata) {
 
     @NonNull
     @Override
-    public ItemManager unregister(int layoutId) {
+    public ItemManager<E> unregister(int layoutId) {
         registry.delete(layoutId);
         return this;
     }
diff --git a/library/src/main/java/com/samelody/modapter/AdapterItem.java b/core/src/main/java/com/samelody/modapter/AdapterItem.java
similarity index 100%
rename from library/src/main/java/com/samelody/modapter/AdapterItem.java
rename to core/src/main/java/com/samelody/modapter/AdapterItem.java
diff --git a/library/src/main/java/com/samelody/modapter/ItemManager.java b/core/src/main/java/com/samelody/modapter/ItemManager.java
similarity index 60%
rename from library/src/main/java/com/samelody/modapter/ItemManager.java
rename to core/src/main/java/com/samelody/modapter/ItemManager.java
index 1864578..dc7db3a 100644
--- a/library/src/main/java/com/samelody/modapter/ItemManager.java
+++ b/core/src/main/java/com/samelody/modapter/ItemManager.java
@@ -5,34 +5,60 @@
 import android.support.annotation.Nullable;
 import android.support.v7.widget.RecyclerView.ViewHolder;
 
+import com.samelody.modapter.differ.AsyncDiffer;
+
 import java.util.List;
 
 /**
  * A item manager implements register, unregister and other managing operations.
  *
+ * @param <E> The type of elements in the list.
  * @author Belin Wu
  */
-public interface ItemManager {
+public interface ItemManager<E> {
 
     /**
-     * Sets the list of items.
+     * Sets the async differ.
+     *
+     * @param differ The async differ.
+     * @return this item manager.
+     */
+    ItemManager<E> setDiffer(AsyncDiffer<E> differ);
+
+    /**
+     * Submits the list of items.
      *
      * @param list The list of items.
      * @return this item manager.
      */
     @NonNull
-    ItemManager setList(List<? extends AdapterItem> list);
+    ItemManager<E> submitList(List<? extends E> list);
+
+    /**
+     * Gets the list currently being displayed.
+     *
+     * @return The list.
+     */
+    List<E> getCurrentList();
+
+    /**
+     * Gets the item at the given position.
+     *
+     * @param position The position of item.
+     * @return The item at the given position.
+     */
+    @Nullable
+    E getItem(int position);
 
     /**
      * Registers the item metadata.
      *
      * @param layoutId The resource id of item layout.
      * @param holderClass The class of view holder.
-     * @param <T> The type of view holder.
      * @return this item manager.
      */
     @NonNull
-    <T extends ViewHolder> ItemManager register(@LayoutRes int layoutId, Class<T> holderClass);
+    ItemManager<E> register(@LayoutRes int layoutId, Class<? extends ViewHolder> holderClass);
 
     /**
      * Registers the item metadata.
@@ -41,7 +67,7 @@ public interface ItemManager {
      * @return this item manager.
      */
     @NonNull
-    ItemManager register(ItemMetadata metadata);
+    ItemManager<E> register(ItemMetadata metadata);
 
     /**
      * Unregisters the item metadata.
@@ -50,15 +76,5 @@ public interface ItemManager {
      * @return this item manager.
      */
     @NonNull
-    ItemManager unregister(@LayoutRes int layoutId);
-
-    /**
-     * Gets the item at the given position.
-     *
-     * @param position The position of item.
-     * @param <T> The type of item.
-     * @return The item at the given position.
-     */
-    @Nullable
-    <T extends AdapterItem> T getItem(int position);
+    ItemManager<E> unregister(@LayoutRes int layoutId);
 }
diff --git a/library/src/main/java/com/samelody/modapter/ItemMetadata.java b/core/src/main/java/com/samelody/modapter/ItemMetadata.java
similarity index 100%
rename from library/src/main/java/com/samelody/modapter/ItemMetadata.java
rename to core/src/main/java/com/samelody/modapter/ItemMetadata.java
diff --git a/library/src/main/java/com/samelody/modapter/ItemViewHolder.java b/core/src/main/java/com/samelody/modapter/ItemViewHolder.java
old mode 100755
new mode 100644
similarity index 100%
rename from library/src/main/java/com/samelody/modapter/ItemViewHolder.java
rename to core/src/main/java/com/samelody/modapter/ItemViewHolder.java
diff --git a/core/src/main/java/com/samelody/modapter/ModularAdapter.java b/core/src/main/java/com/samelody/modapter/ModularAdapter.java
new file mode 100644
index 0000000..f0a86d3
--- /dev/null
+++ b/core/src/main/java/com/samelody/modapter/ModularAdapter.java
@@ -0,0 +1,125 @@
+package com.samelody.modapter;
+
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+import android.support.v7.widget.RecyclerView;
+import android.support.v7.widget.RecyclerView.Adapter;
+import android.support.v7.widget.RecyclerView.ViewHolder;
+import android.view.ViewGroup;
+
+import com.samelody.modapter.differ.AsyncDiffer;
+
+import java.util.List;
+
+/**
+ * A modular list adapter for presenting List data in a {@link RecyclerView}, including computing
+ * diffs between Lists on a background thread by {@link AsyncDiffer<E>}.
+ *
+ * @param <E> The type of elements in the list.
+ * @author Belin Wu
+ */
+public class ModularAdapter<E extends AdapterItem>
+        extends Adapter<ViewHolder>
+        implements ItemManager<E> {
+
+    /**
+     * The delegated implementation.
+     */
+    private AdapterDelegate<E> delegate = new AdapterDelegate<>();
+
+    @Override
+    public int getItemViewType(int position) {
+        return delegate.getItemViewType(position);
+    }
+
+    @Override
+    public final int getItemCount() {
+        return delegate.getItemCount();
+    }
+
+    @NonNull
+    @Override
+    public final ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
+        return delegate.onCreateViewHolder(parent, viewType);
+    }
+
+    @Override
+    public final void onBindViewHolder(@NonNull ViewHolder holder, int position) {
+        delegate.onBindViewHolder(holder, position);
+    }
+
+    @Override
+    public final void onViewRecycled(@NonNull ViewHolder holder) {
+        super.onViewRecycled(holder);
+        delegate.onViewRecycled(holder);
+    }
+
+    @Override
+    public final void onViewAttachedToWindow(@NonNull ViewHolder holder) {
+        super.onViewAttachedToWindow(holder);
+        delegate.onViewAttachedToWindow(holder);
+    }
+
+    @Override
+    public final void onViewDetachedFromWindow(@NonNull ViewHolder holder) {
+        super.onViewDetachedFromWindow(holder);
+        delegate.onViewDetachedFromWindow(holder);
+    }
+
+    /**
+     * Gets item manager.
+     *
+     * @return The item manager.
+     */
+    public ItemManager<E> getManager() {
+        return delegate;
+    }
+
+    // implements ItemManager interface
+
+    @Override
+    public ItemManager<E> setDiffer(AsyncDiffer<E> differ) {
+        delegate.setDiffer(differ);
+        return delegate;
+    }
+
+    @NonNull
+    @Override
+    public ItemManager<E> submitList(List<? extends E> list) {
+        delegate.submitList(list);
+        return delegate;
+    }
+
+    @Override
+    public List<E> getCurrentList() {
+        return delegate.getCurrentList();
+    }
+
+    @Nullable
+    @Override
+    public E getItem(int position) {
+        return delegate.getItem(position);
+    }
+
+    @NonNull
+    @Override
+    public ItemManager<E> register(int layoutId, Class<? extends ViewHolder> holderClass) {
+        delegate.register(layoutId, holderClass);
+        return delegate;
+    }
+
+    @NonNull
+    @Override
+    public ItemManager<E> register(ItemMetadata metadata) {
+        delegate.register(metadata);
+        return delegate;
+    }
+
+    @NonNull
+    @Override
+    public ItemManager<E> unregister(int layoutId) {
+        delegate.unregister(layoutId);
+        return delegate;
+    }
+}
+
diff --git a/core/src/main/java/com/samelody/modapter/differ/AsyncDiffer.java b/core/src/main/java/com/samelody/modapter/differ/AsyncDiffer.java
new file mode 100644
index 0000000..f1262f8
--- /dev/null
+++ b/core/src/main/java/com/samelody/modapter/differ/AsyncDiffer.java
@@ -0,0 +1,22 @@
+package com.samelody.modapter.differ;
+
+import android.support.annotation.Nullable;
+
+import java.util.List;
+
+/**
+ * The async differ.
+ *
+ * @param <E> The type of elements in the list.
+ * @author Belin Wu
+ */
+public interface AsyncDiffer<E> {
+
+    void submitList(@Nullable List<? extends E> list);
+
+    E getItem(int position);
+
+    int getItemCount();
+
+    List<E> getCurrentList();
+}
diff --git a/core/src/main/java/com/samelody/modapter/differ/ListAsyncDiffer.java b/core/src/main/java/com/samelody/modapter/differ/ListAsyncDiffer.java
new file mode 100644
index 0000000..9b17b16
--- /dev/null
+++ b/core/src/main/java/com/samelody/modapter/differ/ListAsyncDiffer.java
@@ -0,0 +1,58 @@
+package com.samelody.modapter.differ;
+
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+import android.support.v7.recyclerview.extensions.AsyncDifferConfig;
+import android.support.v7.recyclerview.extensions.AsyncListDiffer;
+import android.support.v7.util.DiffUtil;
+import android.support.v7.util.ListUpdateCallback;
+import android.support.v7.widget.RecyclerView;
+
+import java.util.List;
+
+/**
+ * The {@link AsyncListDiffer} implementation of {@link AsyncDiffer<E>}.
+ *
+ * @param <E> The type of elements in the list.
+ * @author Belin Wu
+ */
+public class ListAsyncDiffer<E> implements AsyncDiffer<E> {
+
+    /**
+     * The real async differ.
+     */
+    private final AsyncListDiffer<E> differ;
+
+    public ListAsyncDiffer(@NonNull RecyclerView.Adapter adapter,
+                           @NonNull DiffUtil.ItemCallback<E> callback) {
+        differ = new AsyncListDiffer<>(adapter, callback);
+    }
+
+    public ListAsyncDiffer(@NonNull ListUpdateCallback callback,
+                           @NonNull AsyncDifferConfig<E> config) {
+        differ = new AsyncListDiffer<>(callback, config);
+    }
+
+    @Override
+    public void submitList(@Nullable List<? extends E> list) {
+        differ.submitList((List<E>) list);
+    }
+
+    @Override
+    public E getItem(int position) {
+        if (position < 0 || position >= getCurrentList().size()) {
+            return null;
+        }
+        return getCurrentList().get(position);
+    }
+
+    @Override
+    public int getItemCount() {
+        return getCurrentList().size();
+    }
+
+    @Override
+    public List<E> getCurrentList() {
+        return differ.getCurrentList();
+    }
+}
diff --git a/core/src/main/java/com/samelody/modapter/differ/NonAsyncDiffer.java b/core/src/main/java/com/samelody/modapter/differ/NonAsyncDiffer.java
new file mode 100644
index 0000000..95b677f
--- /dev/null
+++ b/core/src/main/java/com/samelody/modapter/differ/NonAsyncDiffer.java
@@ -0,0 +1,48 @@
+package com.samelody.modapter.differ;
+
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+
+import java.util.Collections;
+import java.util.List;
+
+import static java.util.Collections.emptyList;
+import static java.util.Collections.unmodifiableList;
+
+/**
+ * The non implementation of {@link AsyncDiffer<E>}.
+ *
+ * @param <E> The type of elements in the list.
+ * @author Belin Wu
+ */
+public class NonAsyncDiffer<E> implements AsyncDiffer<E> {
+
+    /**
+     * The list of items.
+     */
+    @NonNull
+    private List<E> list = emptyList();
+
+    @Override
+    public void submitList(@Nullable List<? extends E> list) {
+        this.list = list == null ? Collections.<E>emptyList() : (List<E>) list;
+    }
+
+    @Override
+    public E getItem(int position) {
+        if (position < 0 || position >= list.size()) {
+            return null;
+        }
+        return list.get(position);
+    }
+
+    @Override
+    public int getItemCount() {
+        return list.size();
+    }
+
+    @Override
+    public List<E> getCurrentList() {
+        return unmodifiableList(list);
+    }
+}
diff --git a/library/src/main/res/values/strings.xml b/core/src/main/res/values/strings.xml
similarity index 100%
rename from library/src/main/res/values/strings.xml
rename to core/src/main/res/values/strings.xml
diff --git a/library/src/test/java/com/samelody/modapter/ExampleUnitTest.java b/core/src/test/java/com/samelody/modapter/ExampleUnitTest.java
similarity index 100%
rename from library/src/test/java/com/samelody/modapter/ExampleUnitTest.java
rename to core/src/test/java/com/samelody/modapter/ExampleUnitTest.java
diff --git a/library/src/main/java/com/samelody/modapter/ModularAdapter.java b/library/src/main/java/com/samelody/modapter/ModularAdapter.java
deleted file mode 100644
index b6c4b8f..0000000
--- a/library/src/main/java/com/samelody/modapter/ModularAdapter.java
+++ /dev/null
@@ -1,68 +0,0 @@
-package com.samelody.modapter;
-
-import android.support.annotation.NonNull;
-import android.support.v7.widget.RecyclerView;
-import android.support.v7.widget.RecyclerView.ViewHolder;
-import android.view.ViewGroup;
-
-/**
- * A modular adapter for {@link RecyclerView}.
- *
- * @author Belin Wu
- */
-public class ModularAdapter extends RecyclerView.Adapter<ViewHolder> {
-
-    /**
-     * The delegated implementation.
-     */
-    private AdapterDelegate delegate = new AdapterDelegate();
-
-    @Override
-    public int getItemViewType(int position) {
-        return delegate.getItemViewType(position);
-    }
-
-    @Override
-    public final int getItemCount() {
-        return delegate.getItemCount();
-    }
-
-    @NonNull
-    @Override
-    public final ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
-        return delegate.onCreateViewHolder(parent, viewType);
-    }
-
-    @Override
-    public final void onBindViewHolder(@NonNull ViewHolder holder, int position) {
-        delegate.onBindViewHolder(holder, position);
-    }
-
-    @Override
-    public final void onViewRecycled(@NonNull ViewHolder holder) {
-        super.onViewRecycled(holder);
-        delegate.onViewRecycled(holder);
-    }
-
-    @Override
-    public final void onViewAttachedToWindow(@NonNull ViewHolder holder) {
-        super.onViewAttachedToWindow(holder);
-        delegate.onViewAttachedToWindow(holder);
-    }
-
-    @Override
-    public final void onViewDetachedFromWindow(@NonNull ViewHolder holder) {
-        super.onViewDetachedFromWindow(holder);
-        delegate.onViewDetachedFromWindow(holder);
-    }
-
-    /**
-     * Gets item manager.
-     *
-     * @return The item manager.
-     */
-    public ItemManager getManager() {
-        return delegate;
-    }
-}
-
diff --git a/paging/.gitignore b/paging/.gitignore
new file mode 100644
index 0000000..d0b97c6
--- /dev/null
+++ b/paging/.gitignore
@@ -0,0 +1,2 @@
+/build
+*.iml
\ No newline at end of file
diff --git a/paging/build.gradle b/paging/build.gradle
new file mode 100644
index 0000000..7675e4f
--- /dev/null
+++ b/paging/build.gradle
@@ -0,0 +1,53 @@
+apply plugin: 'com.android.library'
+
+ext.pubspec = [:]
+
+pubspec.packaging = 'aar'
+pubspec.groupId = 'com.samelody.modapter'
+pubspec.artifactId = 'modapter-paging'
+pubspec.repo = 'maven'
+pubspec.name = 'Modapter'
+pubspec.description = 'Modular adapter for Android RecyclerView.'
+pubspec.version = "0.2.0-alpha1"
+pubspec.versionCode = 2
+pubspec.url = 'https://github.com/samelody/modapter'
+pubspec.gitUrl = 'https://github.com/samelody/modapter.git'
+pubspec.issueUrl = 'https://github.com/samelody/modapter/issues'
+pubspec.developerId = 'belinwu'
+pubspec.developerName = 'Belin Wu'
+pubspec.developerEmail = 'belinwu@qq.com'
+pubspec.licenseName = 'Apache License 2.0'
+pubspec.licenseUrl = 'https://raw.githubusercontent.com/samelody/modapter/master/LICENSE'
+pubspec.licenses = ["Apache-2.0"]
+
+android {
+    compileSdkVersion deps.compileSdk
+    defaultConfig {
+        minSdkVersion deps.minSdk
+        targetSdkVersion deps.targetSdk
+        versionCode pubspec.versionCode
+        versionName pubspec.version
+        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
+    }
+
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
+        }
+    }
+
+}
+
+dependencies {
+    implementation fileTree(dir: 'libs', include: ['*.jar'])
+    implementation deps.paging
+    implementation project(':core')
+
+    testImplementation deps.junit
+
+    androidTestImplementation deps.test
+    androidTestImplementation deps.espresso
+}
+
+apply from: "https://raw.githubusercontent.com/samelody/pubman/master/pub.gradle"
\ No newline at end of file
diff --git a/paging/proguard-rules.pro b/paging/proguard-rules.pro
new file mode 100644
index 0000000..f1b4245
--- /dev/null
+++ b/paging/proguard-rules.pro
@@ -0,0 +1,21 @@
+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile
diff --git a/paging/src/androidTest/java/com/samelody/modapter/ExampleInstrumentedTest.java b/paging/src/androidTest/java/com/samelody/modapter/ExampleInstrumentedTest.java
new file mode 100644
index 0000000..3ce234f
--- /dev/null
+++ b/paging/src/androidTest/java/com/samelody/modapter/ExampleInstrumentedTest.java
@@ -0,0 +1,26 @@
+package com.samelody.modapter;
+
+import android.content.Context;
+import android.support.test.InstrumentationRegistry;
+import android.support.test.runner.AndroidJUnit4;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import static org.junit.Assert.*;
+
+/**
+ * Instrumented test, which will execute on an Android device.
+ *
+ * @see <a href="http://d.android.com/tools/testing">Testing documentation</a>
+ */
+@RunWith(AndroidJUnit4.class)
+public class ExampleInstrumentedTest {
+    @Test
+    public void useAppContext() {
+        // Context of the app under test.
+        Context appContext = InstrumentationRegistry.getTargetContext();
+
+        assertEquals("com.samelody.modapter.test", appContext.getPackageName());
+    }
+}
diff --git a/paging/src/main/AndroidManifest.xml b/paging/src/main/AndroidManifest.xml
new file mode 100644
index 0000000..9232b13
--- /dev/null
+++ b/paging/src/main/AndroidManifest.xml
@@ -0,0 +1,2 @@
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+          package="com.samelody.modapter.paging"/>
diff --git a/paging/src/main/java/com/samelody/modapter/differ/PagedAsyncDiffer.java b/paging/src/main/java/com/samelody/modapter/differ/PagedAsyncDiffer.java
new file mode 100644
index 0000000..4ce127a
--- /dev/null
+++ b/paging/src/main/java/com/samelody/modapter/differ/PagedAsyncDiffer.java
@@ -0,0 +1,66 @@
+package com.samelody.modapter.differ;
+
+import android.arch.paging.AsyncPagedListDiffer;
+import android.arch.paging.PagedList;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+import android.support.v7.recyclerview.extensions.AsyncDifferConfig;
+import android.support.v7.util.DiffUtil;
+import android.support.v7.util.ListUpdateCallback;
+import android.support.v7.widget.RecyclerView;
+
+import java.util.List;
+
+/**
+ * The {@link AsyncPagedListDiffer} implementation of {@link AsyncDiffer<E>}.
+ *
+ * @param <E> The type of elements in the list.
+ * @author Belin Wu
+ */
+public class PagedAsyncDiffer<E> implements AsyncDiffer<E> {
+
+    /**
+     * The real async differ.
+     */
+    private final AsyncPagedListDiffer<E> differ;
+
+    public PagedAsyncDiffer(@NonNull RecyclerView.Adapter adapter,
+                            @NonNull DiffUtil.ItemCallback<E> callback) {
+        differ = new AsyncPagedListDiffer<>(adapter, callback);
+    }
+
+    public PagedAsyncDiffer(@NonNull ListUpdateCallback listUpdateCallback,
+                            @NonNull AsyncDifferConfig<E> config) {
+        differ = new AsyncPagedListDiffer<>(listUpdateCallback, config);
+    }
+
+    @Override
+    public void submitList(@Nullable List<? extends E> list) {
+        if (list instanceof PagedList) {
+            differ.submitList((PagedList<E>) list);
+            return;
+        }
+        throw new IllegalArgumentException("list is not a PagedList");
+    }
+
+    @Override
+    public E getItem(int position) {
+        if (getCurrentList() == null) {
+            return null;
+        }
+        if (position < 0 || position >= getCurrentList().size()) {
+            return null;
+        }
+        return getCurrentList().get(position);
+    }
+
+    @Override
+    public int getItemCount() {
+        return differ.getItemCount();
+    }
+
+    @Override
+    public List<E> getCurrentList() {
+        return differ.getCurrentList();
+    }
+}
diff --git a/paging/src/main/java/com/samelody/modapter/package-info.java b/paging/src/main/java/com/samelody/modapter/package-info.java
new file mode 100644
index 0000000..5c1cab7
--- /dev/null
+++ b/paging/src/main/java/com/samelody/modapter/package-info.java
@@ -0,0 +1 @@
+package com.samelody.modapter;
\ No newline at end of file
diff --git a/paging/src/main/res/values/strings.xml b/paging/src/main/res/values/strings.xml
new file mode 100644
index 0000000..75700a2
--- /dev/null
+++ b/paging/src/main/res/values/strings.xml
@@ -0,0 +1,3 @@
+<resources>
+    <string name="app_name">Modapter</string>
+</resources>
diff --git a/paging/src/test/java/com/samelody/modapter/ExampleUnitTest.java b/paging/src/test/java/com/samelody/modapter/ExampleUnitTest.java
new file mode 100644
index 0000000..21d949e
--- /dev/null
+++ b/paging/src/test/java/com/samelody/modapter/ExampleUnitTest.java
@@ -0,0 +1,17 @@
+package com.samelody.modapter;
+
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+/**
+ * Example local unit test, which will execute on the development machine (host).
+ *
+ * @see <a href="http://d.android.com/tools/testing">Testing documentation</a>
+ */
+public class ExampleUnitTest {
+    @Test
+    public void addition_isCorrect() {
+        assertEquals(4, 2 + 2);
+    }
+}
\ No newline at end of file
diff --git a/sample/build.gradle b/sample/build.gradle
index 82ba85b..ca3f45b 100644
--- a/sample/build.gradle
+++ b/sample/build.gradle
@@ -6,8 +6,8 @@ android {
         applicationId "com.samelody.samples.modapter"
         minSdkVersion deps.minSdk
         targetSdkVersion deps.targetSdk
-        versionCode deps.demoVersionCode
-        versionName deps.demoVersionName
+        versionCode 2
+        versionName "0.2.0-alpha1"
         testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
     }
     buildTypes {
@@ -20,7 +20,8 @@ android {
 
 dependencies {
     implementation fileTree(dir: 'libs', include: ['*.jar'])
-    implementation project(':library')
+    implementation project(':core')
+    implementation project(':paging')
 //    implementation "com.samelody.modapter:modapter:0.1.0"
     implementation deps.appcompat
     implementation deps.recyclerview
diff --git a/sample/src/main/java/com/samelody/samples/modapter/MainActivity.java b/sample/src/main/java/com/samelody/samples/modapter/MainActivity.java
index 2d0dda0..64bf513 100644
--- a/sample/src/main/java/com/samelody/samples/modapter/MainActivity.java
+++ b/sample/src/main/java/com/samelody/samples/modapter/MainActivity.java
@@ -4,39 +4,39 @@
 import android.support.v7.app.AppCompatActivity;
 import android.support.v7.widget.RecyclerView;
 
+import com.samelody.modapter.AbstractItem;
+import com.samelody.modapter.ItemManager;
 import com.samelody.modapter.ModularAdapter;
-import com.samelody.modapter.AdapterItem;
 
 import java.util.ArrayList;
 import java.util.List;
 
 public class MainActivity extends AppCompatActivity {
 
-    private RecyclerView listView;
-
-    private ModularAdapter adapter;
-
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
 
-        listView = findViewById(R.id.list);
-        adapter = new ModularAdapter();
+        RecyclerView listView = findViewById(R.id.list);
+        ModularAdapter<AbstractItem> adapter = new ModularAdapter<>();
         listView.setAdapter(adapter);
 
-        adapter.getManager()
-                .register(R.layout.item_gallery_image, ImageViewHolder.class)
+        ItemManager<AbstractItem> manager = adapter.getManager();
+        manager.register(R.layout.item_gallery_image, ImageViewHolder.class)
                 .register(R.layout.item_gallery_date, DateViewHolder.class);
 
-        adapter.getManager().unregister(R.layout.item_gallery_image);
+        manager.unregister(R.layout.item_gallery_image);
 
-        List<AdapterItem> list = new ArrayList<>();
+        List<ImageItem> list = new ArrayList<>();
         list.add(new ImageItem());
-        list.add(new DateItem());
         list.add(new ImageItem());
         list.add(new ImageItem());
-        adapter.getManager().setList(list);
+        list.add(new ImageItem());
+        adapter.submitList(list);
         adapter.notifyDataSetChanged();
+
+        manager.getCurrentList();
+        adapter.getItem(0);
     }
 }
diff --git a/settings.gradle b/settings.gradle
index 52baf7e..47aac0c 100644
--- a/settings.gradle
+++ b/settings.gradle
@@ -1 +1 @@
-include ':sample', ':library'
+include ':sample', ':core', ':paging'

From 1fa8d773469e256e4e430557fe28ecfcf17d164b Mon Sep 17 00:00:00 2001
From: Belin Wu <belinwu@qq.com>
Date: Fri, 25 Jan 2019 16:37:16 +0800
Subject: [PATCH 2/3] Reimplement `AsyncDiffer#getItem()` method

- More docs.
- `ModularAdapter` no longer implements `ItemManager`.
- New `getItemCount()` method of `ItemManager` interface.
---
 .../samelody/modapter/AdapterDelegate.java    |  1 +
 .../com/samelody/modapter/ItemManager.java    |  7 +++
 .../com/samelody/modapter/ItemViewHolder.java | 16 +++++-
 .../com/samelody/modapter/ModularAdapter.java | 54 +------------------
 .../samelody/modapter/differ/AsyncDiffer.java | 21 ++++++++
 .../modapter/differ/ListAsyncDiffer.java      | 14 +++--
 .../modapter/differ/NonAsyncDiffer.java       | 28 ++++++++--
 .../modapter/differ/PagedAsyncDiffer.java     | 21 +++-----
 .../samples/modapter/MainActivity.java        |  4 +-
 9 files changed, 85 insertions(+), 81 deletions(-)

diff --git a/core/src/main/java/com/samelody/modapter/AdapterDelegate.java b/core/src/main/java/com/samelody/modapter/AdapterDelegate.java
index 8263bc7..856029c 100644
--- a/core/src/main/java/com/samelody/modapter/AdapterDelegate.java
+++ b/core/src/main/java/com/samelody/modapter/AdapterDelegate.java
@@ -52,6 +52,7 @@ private void checkDiffer(AsyncDiffer<E> differ) {
      *
      * @return The item count.
      */
+    @Override
     public int getItemCount() {
         return differ.getItemCount();
     }
diff --git a/core/src/main/java/com/samelody/modapter/ItemManager.java b/core/src/main/java/com/samelody/modapter/ItemManager.java
index dc7db3a..c9a4893 100644
--- a/core/src/main/java/com/samelody/modapter/ItemManager.java
+++ b/core/src/main/java/com/samelody/modapter/ItemManager.java
@@ -50,6 +50,13 @@ public interface ItemManager<E> {
     @Nullable
     E getItem(int position);
 
+    /**
+     * Gets item count of current list.
+     *
+     * @return The item count of current list.
+     */
+    int getItemCount();
+
     /**
      * Registers the item metadata.
      *
diff --git a/core/src/main/java/com/samelody/modapter/ItemViewHolder.java b/core/src/main/java/com/samelody/modapter/ItemViewHolder.java
index b48dd89..bcb5b71 100644
--- a/core/src/main/java/com/samelody/modapter/ItemViewHolder.java
+++ b/core/src/main/java/com/samelody/modapter/ItemViewHolder.java
@@ -8,7 +8,7 @@
 /**
  * A holder with bound data item for item view.
  *
- * @param <T> The type of item.
+ * @param <T> The type of data item.
  * @author Belin Wu
  */
 public abstract class ItemViewHolder<T extends AdapterItem> extends ViewHolder {
@@ -27,18 +27,32 @@ void setItem(@Nullable T item) {
         this.item = item;
     }
 
+    /**
+     * Called when item view has been bound.
+     *
+     * @param item The data item bound within this view holder.
+     */
     protected void onViewBound(T item) {
         // empty
     }
 
+    /**
+     * Called when item view has been recycled.
+     */
     protected void onViewRecycled() {
         // empty
     }
 
+    /**
+     * Called when item view has been attached to a window.
+     */
     protected void onViewAttachedToWindow() {
         // empty
     }
 
+    /**
+     * Called when item view has been detached from its window.
+     */
     protected void onViewDetachedFromWindow() {
         // empty
     }
diff --git a/core/src/main/java/com/samelody/modapter/ModularAdapter.java b/core/src/main/java/com/samelody/modapter/ModularAdapter.java
index f0a86d3..077898e 100644
--- a/core/src/main/java/com/samelody/modapter/ModularAdapter.java
+++ b/core/src/main/java/com/samelody/modapter/ModularAdapter.java
@@ -1,7 +1,6 @@
 package com.samelody.modapter;
 
 import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
 import android.support.v7.widget.RecyclerView;
 import android.support.v7.widget.RecyclerView.Adapter;
 import android.support.v7.widget.RecyclerView.ViewHolder;
@@ -9,8 +8,6 @@
 
 import com.samelody.modapter.differ.AsyncDiffer;
 
-import java.util.List;
-
 /**
  * A modular list adapter for presenting List data in a {@link RecyclerView}, including computing
  * diffs between Lists on a background thread by {@link AsyncDiffer<E>}.
@@ -18,9 +15,7 @@
  * @param <E> The type of elements in the list.
  * @author Belin Wu
  */
-public class ModularAdapter<E extends AdapterItem>
-        extends Adapter<ViewHolder>
-        implements ItemManager<E> {
+public class ModularAdapter<E extends AdapterItem> extends Adapter<ViewHolder> {
 
     /**
      * The delegated implementation.
@@ -74,52 +69,5 @@ public final void onViewDetachedFromWindow(@NonNull ViewHolder holder) {
     public ItemManager<E> getManager() {
         return delegate;
     }
-
-    // implements ItemManager interface
-
-    @Override
-    public ItemManager<E> setDiffer(AsyncDiffer<E> differ) {
-        delegate.setDiffer(differ);
-        return delegate;
-    }
-
-    @NonNull
-    @Override
-    public ItemManager<E> submitList(List<? extends E> list) {
-        delegate.submitList(list);
-        return delegate;
-    }
-
-    @Override
-    public List<E> getCurrentList() {
-        return delegate.getCurrentList();
-    }
-
-    @Nullable
-    @Override
-    public E getItem(int position) {
-        return delegate.getItem(position);
-    }
-
-    @NonNull
-    @Override
-    public ItemManager<E> register(int layoutId, Class<? extends ViewHolder> holderClass) {
-        delegate.register(layoutId, holderClass);
-        return delegate;
-    }
-
-    @NonNull
-    @Override
-    public ItemManager<E> register(ItemMetadata metadata) {
-        delegate.register(metadata);
-        return delegate;
-    }
-
-    @NonNull
-    @Override
-    public ItemManager<E> unregister(int layoutId) {
-        delegate.unregister(layoutId);
-        return delegate;
-    }
 }
 
diff --git a/core/src/main/java/com/samelody/modapter/differ/AsyncDiffer.java b/core/src/main/java/com/samelody/modapter/differ/AsyncDiffer.java
index f1262f8..b14e1c3 100644
--- a/core/src/main/java/com/samelody/modapter/differ/AsyncDiffer.java
+++ b/core/src/main/java/com/samelody/modapter/differ/AsyncDiffer.java
@@ -12,11 +12,32 @@
  */
 public interface AsyncDiffer<E> {
 
+    /**
+     * Submits the new list to be displayed.
+     *
+     * @param list The new list to be displayed.
+     */
     void submitList(@Nullable List<? extends E> list);
 
+    /**
+     * Get the item from the current list at the specified index.
+     *
+     * @param position The position of item.
+     * @return The item at the given position.
+     */
     E getItem(int position);
 
+    /**
+     * Gets item count of current list.
+     *
+     * @return The item count of current list.
+     */
     int getItemCount();
 
+    /**
+     * Gets the list currently being displayed by the Adapter.
+     *
+     * @return The list currently being displayed.
+     */
     List<E> getCurrentList();
 }
diff --git a/core/src/main/java/com/samelody/modapter/differ/ListAsyncDiffer.java b/core/src/main/java/com/samelody/modapter/differ/ListAsyncDiffer.java
index 9b17b16..385cd30 100644
--- a/core/src/main/java/com/samelody/modapter/differ/ListAsyncDiffer.java
+++ b/core/src/main/java/com/samelody/modapter/differ/ListAsyncDiffer.java
@@ -4,9 +4,9 @@
 import android.support.annotation.Nullable;
 import android.support.v7.recyclerview.extensions.AsyncDifferConfig;
 import android.support.v7.recyclerview.extensions.AsyncListDiffer;
-import android.support.v7.util.DiffUtil;
+import android.support.v7.util.DiffUtil.ItemCallback;
 import android.support.v7.util.ListUpdateCallback;
-import android.support.v7.widget.RecyclerView;
+import android.support.v7.widget.RecyclerView.Adapter;
 
 import java.util.List;
 
@@ -23,8 +23,8 @@ public class ListAsyncDiffer<E> implements AsyncDiffer<E> {
      */
     private final AsyncListDiffer<E> differ;
 
-    public ListAsyncDiffer(@NonNull RecyclerView.Adapter adapter,
-                           @NonNull DiffUtil.ItemCallback<E> callback) {
+    public ListAsyncDiffer(@NonNull Adapter adapter,
+                           @NonNull ItemCallback<E> callback) {
         differ = new AsyncListDiffer<>(adapter, callback);
     }
 
@@ -33,6 +33,7 @@ public ListAsyncDiffer(@NonNull ListUpdateCallback callback,
         differ = new AsyncListDiffer<>(callback, config);
     }
 
+    @SuppressWarnings("unchecked")
     @Override
     public void submitList(@Nullable List<? extends E> list) {
         differ.submitList((List<E>) list);
@@ -40,10 +41,7 @@ public void submitList(@Nullable List<? extends E> list) {
 
     @Override
     public E getItem(int position) {
-        if (position < 0 || position >= getCurrentList().size()) {
-            return null;
-        }
-        return getCurrentList().get(position);
+        return NonAsyncDiffer.getItem(this, position);
     }
 
     @Override
diff --git a/core/src/main/java/com/samelody/modapter/differ/NonAsyncDiffer.java b/core/src/main/java/com/samelody/modapter/differ/NonAsyncDiffer.java
index 95b677f..1cc4bd7 100644
--- a/core/src/main/java/com/samelody/modapter/differ/NonAsyncDiffer.java
+++ b/core/src/main/java/com/samelody/modapter/differ/NonAsyncDiffer.java
@@ -23,6 +23,7 @@ public class NonAsyncDiffer<E> implements AsyncDiffer<E> {
     @NonNull
     private List<E> list = emptyList();
 
+    @SuppressWarnings("unchecked")
     @Override
     public void submitList(@Nullable List<? extends E> list) {
         this.list = list == null ? Collections.<E>emptyList() : (List<E>) list;
@@ -30,10 +31,7 @@ public void submitList(@Nullable List<? extends E> list) {
 
     @Override
     public E getItem(int position) {
-        if (position < 0 || position >= list.size()) {
-            return null;
-        }
-        return list.get(position);
+        return getItem(this, position);
     }
 
     @Override
@@ -45,4 +43,26 @@ public int getItemCount() {
     public List<E> getCurrentList() {
         return unmodifiableList(list);
     }
+
+    /**
+     * Gets the item with given position from given differ.
+     *
+     * @param differ The async differ.
+     * @param position The position of item.
+     * @param <E> The type of item.
+     * @return The item at given position.
+     */
+    @Nullable
+    public static <E> E getItem(AsyncDiffer<E> differ, int position) {
+        if (differ == null) {
+            return null;
+        }
+
+        List<E> list = differ.getCurrentList();
+        if (list == null || position < 0 || position >= list.size()) {
+            return null;
+        }
+
+        return list.get(position);
+    }
 }
diff --git a/paging/src/main/java/com/samelody/modapter/differ/PagedAsyncDiffer.java b/paging/src/main/java/com/samelody/modapter/differ/PagedAsyncDiffer.java
index 4ce127a..74c47ec 100644
--- a/paging/src/main/java/com/samelody/modapter/differ/PagedAsyncDiffer.java
+++ b/paging/src/main/java/com/samelody/modapter/differ/PagedAsyncDiffer.java
@@ -5,9 +5,9 @@
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import android.support.v7.recyclerview.extensions.AsyncDifferConfig;
-import android.support.v7.util.DiffUtil;
+import android.support.v7.util.DiffUtil.ItemCallback;
 import android.support.v7.util.ListUpdateCallback;
-import android.support.v7.widget.RecyclerView;
+import android.support.v7.widget.RecyclerView.Adapter;
 
 import java.util.List;
 
@@ -24,16 +24,17 @@ public class PagedAsyncDiffer<E> implements AsyncDiffer<E> {
      */
     private final AsyncPagedListDiffer<E> differ;
 
-    public PagedAsyncDiffer(@NonNull RecyclerView.Adapter adapter,
-                            @NonNull DiffUtil.ItemCallback<E> callback) {
+    public PagedAsyncDiffer(@NonNull Adapter adapter,
+                            @NonNull ItemCallback<E> callback) {
         differ = new AsyncPagedListDiffer<>(adapter, callback);
     }
 
-    public PagedAsyncDiffer(@NonNull ListUpdateCallback listUpdateCallback,
+    public PagedAsyncDiffer(@NonNull ListUpdateCallback callback,
                             @NonNull AsyncDifferConfig<E> config) {
-        differ = new AsyncPagedListDiffer<>(listUpdateCallback, config);
+        differ = new AsyncPagedListDiffer<>(callback, config);
     }
 
+    @SuppressWarnings("unchecked")
     @Override
     public void submitList(@Nullable List<? extends E> list) {
         if (list instanceof PagedList) {
@@ -45,13 +46,7 @@ public void submitList(@Nullable List<? extends E> list) {
 
     @Override
     public E getItem(int position) {
-        if (getCurrentList() == null) {
-            return null;
-        }
-        if (position < 0 || position >= getCurrentList().size()) {
-            return null;
-        }
-        return getCurrentList().get(position);
+        return NonAsyncDiffer.getItem(this, position);
     }
 
     @Override
diff --git a/sample/src/main/java/com/samelody/samples/modapter/MainActivity.java b/sample/src/main/java/com/samelody/samples/modapter/MainActivity.java
index 64bf513..8d90237 100644
--- a/sample/src/main/java/com/samelody/samples/modapter/MainActivity.java
+++ b/sample/src/main/java/com/samelody/samples/modapter/MainActivity.java
@@ -33,10 +33,10 @@ protected void onCreate(Bundle savedInstanceState) {
         list.add(new ImageItem());
         list.add(new ImageItem());
         list.add(new ImageItem());
-        adapter.submitList(list);
+        manager.submitList(list);
         adapter.notifyDataSetChanged();
 
         manager.getCurrentList();
-        adapter.getItem(0);
+        manager.getItem(0);
     }
 }

From 85813f9e1fefff30de97e9def4a6feb95d1dbf51 Mon Sep 17 00:00:00 2001
From: Belin Wu <belinwu@qq.com>
Date: Fri, 25 Jan 2019 17:39:23 +0800
Subject: [PATCH 3/3] Prepare v0.2.0 release

---
 README.md                                     | 66 +++++++++++++++----
 core/build.gradle                             |  2 +-
 paging/build.gradle                           |  2 +-
 sample/build.gradle                           |  5 +-
 .../samples/modapter/MainActivity.java        | 12 ++--
 5 files changed, 64 insertions(+), 23 deletions(-)

diff --git a/README.md b/README.md
index 297e26f..17f1703 100644
--- a/README.md
+++ b/README.md
@@ -10,11 +10,16 @@ Modular adapter for Android RecyclerView.
 **DO NOT USE THIS LIBRARY IN PRODUCTION UNTIL V1.0.0 IS RELEASED.**
 
 # Installation
+
 Add the following dependency to your `build.gradle` file:
 
 ```groovy
 dependencies {
-    implementation 'com.samelody.modapter:modapter:0.1.0'
+    // required, core
+    implementation 'com.samelody.modapter:modapter-core:0.2.0'
+    
+    // optional, support android paging library
+    implementation 'com.samelody.modapter:modapter-paging:0.2.0'
 }
 ```
 
@@ -22,11 +27,11 @@ dependencies {
 
 ```java
 // create a ModularAdapter object instead of creating new Subclass of RecyclerView.Adapter.
-ModularAdapter adapter = new ModularAdapter();
-recyclerView.setAdapter(adapter);
+ModularAdapter<AdapterItem> adapter = new ModularAdapter<>();
+listView.setAdapter(adapter);
 
 // register item metadata to manager
-ItemManager manager = adapter.getManager();
+ItemManager<AdapterItem> manager = adapter.getManager();
 manager.register(R.layout.item_gallery_image, ImageViewHolder.class)
         .register(R.layout.item_gallery_date, DateViewHolder.class);
 
@@ -35,32 +40,67 @@ List<Item> list = new ArrayList<>();
 list.add(new ImageItem());
 list.add(new DateItem());
 
-// Setup list and notify
-manager.setList(list);
+// submit list
+manager.submitList(list);
+
+// notify adapter if no async differs used
 adapter.notifyDataSetChanged();
 ```
 
-# Docs
+## AsyncDiffer
+
+The `ItemManager` not enable async diffing by default.
+
+You can setup `AsyncDiffer` by your choice. The setting API is
+
+`ItemManager#setDiffer()`.
+
+The implemented async differs are following:
+
+- `NonAsyncDiffer`: The non implementation. (default used)
+- `ListAsyncDiffer`: The `AsyncListDiffer` implementation.
+- `PagedAsyncDiffer`: The `AsyncPagedListDiffer` implementation.
+
+### Using Async Differ
+
+```java
+// set differ
+manager.setDiffer(new ListAsyncDiffer<>());
+
+// submit list
+manager.submitList(list);
+
+// not need to call adapter.notify APIs
+```
 
 ## ItemManager
 
-All APIs are encapsulated in `ItemManager` interface returned by `ModularAdapter#getItemManager()`.
+All APIs are encapsulated in `ItemManager` interface returned by `ModularAdapter#getManager()`.
 
 ```java
 // register via layoutId and holderClass
-ItemManager register(@LayoutRes int layoutId, Class<T> holderClass);
+ItemManager<E> register(@LayoutRes int layoutId, Class<T> holderClass);
 
 // register via ItemMetadata
-ItemManager register(ItemMetadata metadata);
+ItemManager<E> register(ItemMetadata metadata);
 
 // unregister via layoutId
-ItemManager unregister(@LayoutRes int layoutId);
+ItemManager<E> unregister(@LayoutRes int layoutId);
 
 // setup the data list
-ItemManager setList(List<? extends AdapterItem> list);
+ItemManager<E> submitList(List<? extends E> list);
 
 // Gets the item with given position
-T getItem(int position);
+E getItem(int position);
+
+// Gets current displayed list
+List<E> getCurrentList();
+
+// Gets item count
+int getItemCount();
+
+// setup async differ
+ItemManager<E> setDiffer(AsyncDiffer<E> differ);
 ```
 
 # License
diff --git a/core/build.gradle b/core/build.gradle
index 6bbf8ed..3896bcb 100644
--- a/core/build.gradle
+++ b/core/build.gradle
@@ -8,7 +8,7 @@ pubspec.artifactId = 'modapter-core'
 pubspec.repo = 'maven'
 pubspec.name = 'Modapter'
 pubspec.description = 'Modular adapter for Android RecyclerView.'
-pubspec.version = "0.2.0-alpha1"
+pubspec.version = "0.2.0"
 pubspec.versionCode = 2
 pubspec.url = 'https://github.com/samelody/modapter'
 pubspec.gitUrl = 'https://github.com/samelody/modapter.git'
diff --git a/paging/build.gradle b/paging/build.gradle
index 7675e4f..84fd93d 100644
--- a/paging/build.gradle
+++ b/paging/build.gradle
@@ -8,7 +8,7 @@ pubspec.artifactId = 'modapter-paging'
 pubspec.repo = 'maven'
 pubspec.name = 'Modapter'
 pubspec.description = 'Modular adapter for Android RecyclerView.'
-pubspec.version = "0.2.0-alpha1"
+pubspec.version = "0.2.0"
 pubspec.versionCode = 2
 pubspec.url = 'https://github.com/samelody/modapter'
 pubspec.gitUrl = 'https://github.com/samelody/modapter.git'
diff --git a/sample/build.gradle b/sample/build.gradle
index ca3f45b..35db2b0 100644
--- a/sample/build.gradle
+++ b/sample/build.gradle
@@ -7,7 +7,7 @@ android {
         minSdkVersion deps.minSdk
         targetSdkVersion deps.targetSdk
         versionCode 2
-        versionName "0.2.0-alpha1"
+        versionName "0.2.0"
         testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
     }
     buildTypes {
@@ -22,7 +22,8 @@ dependencies {
     implementation fileTree(dir: 'libs', include: ['*.jar'])
     implementation project(':core')
     implementation project(':paging')
-//    implementation "com.samelody.modapter:modapter:0.1.0"
+//    implementation "com.samelody.modapter:modapter-core:0.2.0"
+//    implementation "com.samelody.modapter:modapter-paging:0.2.0"
     implementation deps.appcompat
     implementation deps.recyclerview
     implementation deps.constraintlayout
diff --git a/sample/src/main/java/com/samelody/samples/modapter/MainActivity.java b/sample/src/main/java/com/samelody/samples/modapter/MainActivity.java
index 8d90237..117a60d 100644
--- a/sample/src/main/java/com/samelody/samples/modapter/MainActivity.java
+++ b/sample/src/main/java/com/samelody/samples/modapter/MainActivity.java
@@ -4,7 +4,7 @@
 import android.support.v7.app.AppCompatActivity;
 import android.support.v7.widget.RecyclerView;
 
-import com.samelody.modapter.AbstractItem;
+import com.samelody.modapter.AdapterItem;
 import com.samelody.modapter.ItemManager;
 import com.samelody.modapter.ModularAdapter;
 
@@ -19,20 +19,20 @@ protected void onCreate(Bundle savedInstanceState) {
         setContentView(R.layout.activity_main);
 
         RecyclerView listView = findViewById(R.id.list);
-        ModularAdapter<AbstractItem> adapter = new ModularAdapter<>();
+        ModularAdapter<AdapterItem> adapter = new ModularAdapter<>();
         listView.setAdapter(adapter);
 
-        ItemManager<AbstractItem> manager = adapter.getManager();
+        ItemManager<AdapterItem> manager = adapter.getManager();
         manager.register(R.layout.item_gallery_image, ImageViewHolder.class)
                 .register(R.layout.item_gallery_date, DateViewHolder.class);
 
         manager.unregister(R.layout.item_gallery_image);
 
-        List<ImageItem> list = new ArrayList<>();
-        list.add(new ImageItem());
-        list.add(new ImageItem());
+        List<AdapterItem> list = new ArrayList<>();
         list.add(new ImageItem());
+        list.add(new DateItem());
         list.add(new ImageItem());
+        list.add(new DateItem());
         manager.submitList(list);
         adapter.notifyDataSetChanged();