if逻辑实现的两种方式总结


 1 public class Text1{
 2     public static void main(String[] args){
 3         Singleton s1=Singleton.getSingle();
 4         Singleton s2=Singleton.getSingle();
 5         Singleton s3=Singleton.getSingle();
 6         System.out.println(s3.equals(s2));
 7         System.out.println(s1.equals(s2));
 8         System.out.println(s1.equals(s3));
 9         System.out.println(s3==s2);
10         System.out.println(s1==s2);
11         System.out.println(s1==s3);
12         System.out.println(s1);
13         System.out.println(s2);
14         System.out.println(s3);
15     }
16 }
17 class Singleton{
18     private String name;
19     private static Singleton single=new Singleton();
20     private Singleton(){System.out.println("ddd");name="aa";}
21     public static Singleton getSingle(){
22         return single;
23     }
24     //重写equals方法-----第一步，boolean值返回，第二步，先写false判断，省字省钱，第三步，选择以下两种方式之一写逻辑，第二种阅读性差，代码简洁
25     /*
26     public boolean equals(Singleton single){
27         if(single==null) return false;
28         if(single!=this) return false;
29         if(single.hashCode()!=this.hashCode()) return false;
30         return single.name.equals(this.name) ? true : false;
31     }*/
32     //重写equals方法2-----利用||短路特性来实现
33     
34     public boolean equals(Singleton single){
35         if(single==null||single!=this||single.hashCode()!=this.hashCode()) return false;
36         return single.name.equals(this.name) ? true : false;
37     }
38 }