整理代码块

Author: enjoyCoding666

.classpath

@@ -1,13 +1,47 @@
 package com.date;
 
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
 import java.util.Calendar;
-import java.util.GregorianCalendar;
+import java.util.Date;
 
+/**
+ * @Author: EnjoyCoding
+ * @Date: 2020\5\1 0001 16:17
+ * @Description:
+ */
 public class CalendarDemo {
-    public static void main(String args[]){
-        Calendar calenda=new GregorianCalendar();   //GregorianCalendar是日历的子类。
-        System.out.println("年："+calenda.get(Calendar.YEAR));   //Calendar.YEAR是常量。意指年
 
+	public static void setCalendarTime() throws ParseException {
+		String dateStr="2018-07-07 07:08:11";
+		SimpleDateFormat simpleDateFormat=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
+		Date date = simpleDateFormat.parse(dateStr);
+		Calendar calendar = Calendar.getInstance();
+		//通过calendar设置时间
+		calendar.setTime(date);
+		//获取calendar对应的时间
+		Date time = calendar.getTime();
+		System.out.println(time);
+	}
 
-    }
+	public static void setCalendarMonthDay() {
+		Calendar calendar = Calendar.getInstance();
+		//通过Calendar设置年月日
+		calendar.set(Calendar.MONTH, 7);
+		calendar.set(Calendar.DAY_OF_MONTH, 7);
+		calendar.set(Calendar.YEAR, 2018);
+		calendar.set(Calendar.HOUR_OF_DAY,19);
+		//通过Calendar获取时间，年月日
+		Date date = calendar.getTime();
+		int year = calendar.get(Calendar.YEAR);
+		//Calendar的月份是从0开始计算的，所以要加一才是真实的月份
+		int month = calendar.get(Calendar.MONTH) + 1;
+		int day = calendar.get(Calendar.DAY_OF_MONTH);
+		int hour = calendar.get(Calendar.HOUR_OF_DAY);
+		System.out.println(date);
+		System.out.println("year:" + year);
+		System.out.println("month:" + month);
+		System.out.println("day:" + day);
+		System.out.println("hour:" + hour);
+	}
 }

.project

@@ -1,5 +1,8 @@
 package com.date;
 
+import javax.xml.crypto.Data;
+import java.text.DateFormat;
+import java.text.ParseException;
 import java.text.SimpleDateFormat;
 import java.util.Date;
 
@@ -18,4 +21,41 @@ public static void main(String args[]){
 
 
 	}
+
+	public void dateToString(Date date) {
+		SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");
+		String str=sdf.format(date);
+		System.out.println(date+"转化为字符串是："+str);
+	}
+
+
+	public void stringToDate() {
+		//试着用SimpleDateFormat的parse方法将字符串转化为date类型
+		//MM必须大写。。区分月份和时间
+		DateFormat dateFormat=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
+		String str="2016-5-11 11:06:59";
+		Date date=null;
+		try{
+			/*Date类型的parse方法已经过时了，不可用.一般用SimpleDateFormat的parse */
+			date=dateFormat.parse(str);
+			System.out.println("今天的日期是："+date);
+		}catch(ParseException e) {
+			e.printStackTrace();
+		}
+	}
+
+	public void stringToDate2() {
+		String str="2016-07-21 15:41:52";
+		try {
+			Date date=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").parse(str);
+			System.out.println(DateFormat.getDateInstance().format(date));
+			System.out.println(new SimpleDateFormat("yyyy年MM月dd日").format(date));
+			System.out.println(new SimpleDateFormat("yyyy年MM月dd日 HH:mm:ss").format(date));
+			System.out.println(new SimpleDateFormat("yyyy/MM/dd HH/mm/ss").format(date));
+			System.out.println(new SimpleDateFormat("yyyy-MM-dd").format(date));
+		}catch(Exception e) {
+			e.printStackTrace();
+		}
+	}
+
 }

src/main/java/com/date/CalendarDemo.java

@@ -2,14 +2,14 @@
 
 public class LambdaRunnable {
     public static void main(String[] args) {
-        Runnable race2 = () -> System.out.println("Hello world !");
+        Runnable race2 = () -> System.out.println("HelloWorld world !");
         race2.run();
 
 //        传统的代码表现方式如下：
 //        Runnable race1 = new Runnable() {
 //            @Override
 //            public void run() {
-//                System.out.println("Hello world !");
+//                System.out.println("HelloWorld world !");
 //            }
 //        };
 //        race1.run

src/main/java/com/date/CalendarDemo2.java

@@ -0,0 +1,58 @@
+package com.java8.localdate;
+
+import java.time.LocalDate;
+import java.time.LocalDateTime;
+import java.time.Period;
+import java.time.format.DateTimeFormatter;
+
+/**
+ * @Author: EnjoyCoding
+ * @Date: 2020\4\15 0015 23:31
+ * @Description:
+ */
+public class LocalDateDemo {
+
+
+	public static void main(String[] args) {
+
+//		timeToString();
+
+//		stringToTime();
+
+//		localDateTest();
+
+		monthDiff();
+	}
+
+	private static void timeToString() {
+		// 日期时间转字符串
+		DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
+		//当前时间
+		LocalDateTime now = LocalDateTime.now();
+		String nowText = now.format(formatter);
+		System.out.println("nowText为：" + nowText);
+	}
+
+	private static void stringToTime() {
+		// 字符串转日期时间
+		DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
+		String datetimeText = "2020-04-01 23:59:59";
+		LocalDateTime localDateTime= LocalDateTime.parse(datetimeText, formatter);
+		// LocalDateTime的toString()方法，在日期和时间中间加入了"T"字符串
+		System.out.println(localDateTime);
+	}
+
+	private static void localDateTest() {
+		LocalDate date = LocalDate.of(2000, 1, 1);
+		System.out.println("构造的日期为：" + date);
+	}
+
+	private static void monthDiff(){
+		LocalDate date1 = LocalDate.of(2019, 1, 15);
+		LocalDate date2 = LocalDate.of(2019, 3, 10);
+		Period period = Period.between(date1, date2);
+		System.out.println("相差的年数为"+period.getYears() + "，相差的月数为：" + period.getMonths() +
+				"，相差的天数为：" + period.getDays());
+	}
+
+}

src/main/java/com/date/DateDemo.java

@@ -35,12 +35,12 @@ public static void main(final String... args) {
 
 	public static String functionB() {
 		System.out.println("functionB()...");
-		return "B";
+		return "Son";
 	}
 
 	public static String functionA() {
 		System.out.println("functionA()");
-//		return "A";
+//		return "Father";
 		return null;
 	}
 

src/main/java/com/date/DateTime.java

@@ -0,0 +1,39 @@
+package com.jvm;
+
+/**
+ * @Author: EnjoyCoding
+ * @Date: 2020\4\9 0009 23:10
+ * @Description:
+ */
+public class StringMemoryDemo {
+	public static void main(String[] args) {
+		strMemoryCompare();
+	}
+
+
+	/**
+	 *   String内存模型
+	 *
+	 */
+	public static void strMemoryCompare() {
+		//s1是变量，存放在栈里。"HelloWorld"存放在常量池中
+		String s1 = "HelloWorld";
+		//new String("HelloWorld")是个对象，存放在堆。
+		String s2 = new String("HelloWorld");
+		String s3 = "HelloWorld";
+		String s4 = "World";
+		// "HelloWorld" + "World" 在编译时会被优化成"HelloWorld"
+		String s5 = "HelloWorld" + "World";
+		// 通过加号拼接两个字符串，会在堆上创建的新的对象
+		String s6 = s3 + s4;
+		System.out.println(s1 == s2);			//false,s1指向常量池中的"HelloWorld",s2指向对象String("HelloWorld")
+		System.out.println(s1 == s5);			//true,都指向常量池的"HelloWorld"
+		System.out.println(s1 == s6);			//false,因为s3+s4相当于创建了新对象.
+		// intern()方法会监测常量池中是否有该字符串的值的字面量，有，返回字符串常量的地址，没有，则新建新建字符串常量并返回内存地址。
+		System.out.println(s1 == s6.intern());	//true,都指向常量池中的"HelloWorld"
+		System.out.println(s2 == s2.intern());	//false,s2指向对象,s2.intern()指向常量池"HelloWorld"
+
+
+	}
+
+}

src/main/java/com/date/DateToString.java

@@ -0,0 +1,16 @@
+package com.jvm.staticdemo;
+
+/**
+ * @Author: EnjoyCoding
+ * @Date: 2020\4\11 0011 20:30
+ * @Description:
+ */
+public class Father {
+	static {
+		System.out.println("Father static");
+	}
+
+	public Father() {
+		System.out.println("Father Construct");
+	}
+}

src/main/java/com/date/SimpleDateFormatDemo.java

@@ -0,0 +1,13 @@
+package com.jvm.staticdemo;
+
+/**
+ * @Author: EnjoyCoding
+ * @Date: 2020\4\11 0011 20:42
+ * @Description:
+ */
+public class HelloWorld {
+	public static void main(String[] args) {
+		new Father();
+		new Son();
+	}
+}