使用hashmap存储对象 并获取元素 祛除重复元素需要在类对象中重写hashcode和equal方法哦

package com.heima.maptest;

import java.util.HashMap;
import java.util.Map;

import com.heima.Student.Student;

/**
* 怎么用hashmap存储对象
*
* @author fenuang
*
*/
public class students {

public static void main(String[] args) {
// TODO Auto-generated method stub
Map<Student, String> map = new HashMap<>();
map.put(new Student("张三", 23), "北京");
map.put(new Student("张三", 23), "上海");
map.put(new Student("李四", 24), "广州");
map.put(new Student("王五", 25), "深圳");
/*
* 为确保键值的唯一性,即自己定义的类在set中存储的话,其hashcode值均不相同, 需要重新hashcode来确保相同时键值只有一个
* 还要重写equal方法.
*/
System.out.println(map);

}

}

package com.heima.Student;

public class Student {

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;
}

/**
* @param name
* @param age
*/
public Student(String name, int age) {
super();
this.name = name;
this.age = age;
}

/**
*
*/
public Student() {
super();
// TODO Auto-generated constructor stub
}

@Override
public String toString() {
// TODO Auto-generated method stub
// return "Person : [name=" + name + ", age = " + age + "]";
return "Person : [name = " + name + ", age = " + age + "]";
}

@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + age;
result = prime * result + ((name == null) ? 0 : name.hashCode());
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 (age != other.age)
return false;
if (name == null) {
if (other.name != null)
return false;
} else if (!name.equals(other.name))
return false;
return true;
}

}