Reimplement AsyncDiffer#getItem() method

- More docs. - `ModularAdapter` no longer implements `ItemManager`. - New `getItemCount()` method of `ItemManager` interface.
samelody · Jan 25, 2019 · 1fa8d77 · 1fa8d77
1 parent a8923dc
commit 1fa8d77
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Showing 9 changed files with 85 additions and 81 deletions.
diff --git 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
@@ -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
@@ -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
@@ -1,26 +1,21 @@
 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> {
+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
@@ -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
@@ -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);
     }
 
@@ -33,17 +33,15 @@ 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);
     }
 
     @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
@@ -23,17 +23,15 @@ 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;
     }
 
     @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
@@ -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
@@ -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);
     }
 }