public class HashSetDemo {  public static void main(String[] args){    method_01();        }  public static void method_01(){       /*  toString()方法public String toString()      该方法返回一个字符串，它的值等于：       getClass().getName() + '@' + Integer.toHexString(hashCode())     */      HashSet  ts=new HashSet();      ts.add(new Person("a", 12));      ts.add(new Person("b", 12));      System.out.println(ts.size());  } }class  Person{     private String name;     private int  age;     public Person(String name,int age){     this.name=name;     this.age=age;     }     @Override     //覆写父类的方法    public int hashCode() {    System.out.println("hashCode---->1");      return 1;    }        @Override    public boolean equals(Object obj) {        if(!(obj instanceof Person))            return false; //如果obj不是Person的实例，返回false         Person P1=(Person)obj;         System.out.println(this.age+"..equlas.."+P1.age);         return  this.name.equals(P1.name)&&this.age==P1.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;    }        }