package com.test.collection;import java.util.HashMap;import java.util.Map;/** * 重写equals & hashcode *  * 1.如果两个对象的equals为true ,则hashCode也为true * 2.重写equals时，必须重写hashCode（保证equals为true ,hashCode也为true） * @author chenx * */public class Student {        public Student(int id, String name) {        super();        this.id = id;        this.name = name;    }    private int id;    private String name;    @Override    public int hashCode() {        final int prime = 31;        int result = 1;        result = prime * result + id;        return result;    }    @Override    public boolean equals(Object obj) {        if (this == obj)            return true;        if (obj == null)            return false;        if (getClass() != obj.getClass())            return false;        Student other = (Student) obj;        if (id != other.id)            return false;        return true;    }}