java HashSet存储自定义对象问题

public class Test {
    public static void main(String[] args) {
        HashSet l=new HashSet();
        Students s1=new Students("zhang1",12);
        Students s2=new Students("zhang1",11);
        System.out.println(s1==s2);

        l.add(s1);
        l.add(s2);
        Iterator it=l.iterator();
        System.out.println();
        while(it.hasNext()){
            Students p=(Students)it.next();
            System.out.println(p.getName()+"..."+p.getAge());
        }
        System.out.println(s1);
        System.out.println(s2);
    }

}

public class Students {
    private String name;
    private int age;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public Students(String name, int age) {
        super();
        this.name = name;
        this.age = age;
    }
    public int hashCode() {
        System.out.println("hashcode running...");
        return name.hashCode();
    }
    public boolean equals(Object obj) {
        Students s=(Students)obj;
        System.out.println(this);
        return this.name==s.name && this.age==s.age;
    }
}
输出结果:
false
hashcode running...
hashcode running...
hashcode running...
Test.Students@d61689c5

zhang1...11
zhang1...12
hashcode running...
Test.Students@d61689c5
hashcode running...
Test.Students@d61689c5

问题1:Test类中最后两句话打印s1和s2的地址,结果都是
Test.Students@d61689c5,为什么地址会一样?可是通过s1==s2发现地址是不一样的。
问题2:输出对象的时候,为什么会调用hashcode方法?

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a1670131049
a1670131049
2019/04/29 20:57
  • java
  • eclipse
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