1 /**
 2  * 饿汉模式
 3  */
 4 public class HungrySingleton {
 5     private static  HungrySingleton instance=new HungrySingleton();
 6
 7     /**
 8      * 禁止外部构建
 9      */
10     private HungrySingleton(){}
11
12     /**
13      * 由外部调用
14      * @return
15      */
16     public static HungrySingleton getInstance(){
17         return instance;
18     }
19
20     /**
21      * 测试
22      * @param args
23      */
24     public static void main(String[] args) {
25         for(int i=0;i<20;i++){
26             new Thread(()->{
27                 System.out.println(HungrySingleton.getInstance());
28             }).start();
29         }
30     }
31
32 }

 2 com.company.HungrySingleton@19281561
 3 com.company.HungrySingleton@19281561
 4 com.company.HungrySingleton@19281561
 5 com.company.HungrySingleton@19281561
 6 com.company.HungrySingleton@19281561
 7 com.company.HungrySingleton@19281561
 8 com.company.HungrySingleton@19281561
 9 com.company.HungrySingleton@19281561
10 com.company.HungrySingleton@19281561
11 com.company.HungrySingleton@19281561
12 com.company.HungrySingleton@19281561
13 com.company.HungrySingleton@19281561
14 com.company.HungrySingleton@19281561
15 com.company.HungrySingleton@19281561
16 com.company.HungrySingleton@19281561
17 com.company.HungrySingleton@19281561
18 com.company.HungrySingleton@19281561
19 com.company.HungrySingleton@19281561
20 com.company.HungrySingleton@19281561
21 com.company.HungrySingleton@19281561
22
23 Process finished with exit code 0