if逻辑实现的两种方式总结

 

 1 public class Text1{
    public static void main(String[] args){
        Singleton s1=Singleton.getSingle();
        Singleton s2=Singleton.getSingle();
        Singleton s3=Singleton.getSingle();
        System.out.println(s3.equals(s2));
        System.out.println(s1.equals(s2));
        System.out.println(s1.equals(s3));
        System.out.println(s3==s2);
        System.out.println(s1==s2);
        System.out.println(s1==s3);
        System.out.println(s1);
        System.out.println(s2);
        System.out.println(s3);
    }
}
class Singleton{
    private String name;
    private static Singleton single=new Singleton();
    private Singleton(){System.out.println("ddd");name="aa";}
    public static Singleton getSingle(){
        return single;
    }
    //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
    /*
    public boolean equals(Singleton single){
        if(single==null) return false;
        if(single!=this) return false;
        if(single.hashCode()!=this.hashCode()) return false;
        return single.name.equals(this.name) ? true : false;
    }*/
    //重写equals方法2-----利用||短路特性来实现
    
    public boolean equals(Singleton single){
        if(single==null||single!=this||single.hashCode()!=this.hashCode()) return false;
        return single.name.equals(this.name) ? true : false;
    }
}