add single enum

yi-yun · yi-yun · commit 52a824d51b12 · 2019-05-19T22:00:49.000+08:00
diff --git a/java_test/src/main/java/com/yiyun/SingleEnumTest.java b/java_test/src/main/java/com/yiyun/SingleEnumTest.java
@@ -0,0 +1,20 @@
+package com.yiyun;
+
+public enum SingleEnumTest {
+    SingleFactory;
+    private MySingleton instance;
+
+    SingleEnumTest() {//枚举类的构造方法在类加载是被实例化
+         instance = new MySingleton();
+    }
+
+    public MySingleton getInstance() {
+        return instance;
+    }
+
+}
+
+class MySingleton {
+    public MySingleton() {
+    }
+}
diff --git a/java_test/src/main/java/com/yiyun/TestEnum.java b/java_test/src/main/java/com/yiyun/TestEnum.java
@@ -0,0 +1,11 @@
+package com.yiyun;
+
+public class TestEnum {
+    public static void main(String[] args) {
+        for (int i = 0; i < 10; i++) {
+            new Thread(()->{
+                System.out.println(SingleEnumTest.SingleFactory.getInstance().hashCode());
+            }).start();
+        }
+    }
+}
diff --git a/myoffer/src/main/java/book/offer/_2_Single.java b/myoffer/src/main/java/book/offer/_2_Single.java
@@ -145,22 +145,26 @@ public static void main(String[] args) {
 
 }
 
-class SingleResolve implements Serializable{
+class SingleResolve implements Serializable {
 
     private static final long serialVersionUID = 8396313380667197389L;
-    private static class MySingletonHandler{
+
+    private static class MySingletonHandler {
         private static SingleResolve instance = new SingleResolve();
     }
 
-    private SingleResolve(){}
+    private SingleResolve() {
+    }
 
     public static SingleResolve getInstance() {
         return MySingletonHandler.instance;
     }
+
     protected Object readResolve() throws ObjectStreamException {
         System.out.println("调用了readResolve方法！");
         return MySingletonHandler.instance;
     }
+
     public static void main(String[] args) {
         SingleResolve singleton = SingleResolve.getInstance();
 
@@ -195,6 +199,36 @@ public static void main(String[] args) {
         }
 
     }
+    
+}
+class SingleStatic{
+    private static SingleStatic instance=null;
+    static {
+        instance=new SingleStatic();
+    }
+    private SingleStatic(){
+        System.out.println("eager");
+    }
+    public static SingleStatic getInstance(){
+        return instance;
+    }
 
+    public static void main(String[] args) {
+        
+    }
+}
+
+enum EnumFactory{
+    singletonFactory;
+    private SingleEnum instance;
+    private EnumFactory(){
+        instance=new SingleEnum();
+    }
+    public SingleEnum getInstance(){
+        return instance;
+    }
 
+}
+class SingleEnum{
+    public SingleEnum(){}
 }
