package basic.collection;

import java.util.HashMap;

/**

* ����HashCode��equals����,��дequals�����ͱ�����дhashCode����,

* ��Ϊ�涨equals�����ôhashCode�ͱ������,��Ȼ�Ļ�HashTable��HashMap���������

*

* @author yangqc

* 2016��12��22��

*/

public class TestHashCode {

public static void main(String[] args) {

HashMap<Car, Object> map = new HashMap<>();

Car car1 = new Car("Benz", 120);

Car car2 = new Car("Benz", 120);

System.out.println(car1.equals(car2));

System.out.println(car1.equals(car2));

System.out.println(car1.hashCode() == car2.hashCode());

map.put(car1, 12);

map.put(car2, 13);

System.out.println(map.get(car2));

System.out.println(map.get(car1));

}

}

class Car {

private final String name;

private final int cost;

public Car(String name, int cost) {

this.name = name;

this.cost = cost;

}

/*

* (non-Javadoc)

*

* @see java.lang.Object#hashCode()

*/

@Override

public int hashCode() {

final int prime = 31;

int result = 1;

result = prime * result + cost;

result = prime * result + ((name == null) ? 0 : name.hashCode());

return result;

}

/*

* (non-Javadoc)

*

* @see java.lang.Object#equals(java.lang.Object)

*/

@Override

public boolean equals(Object obj) {

if (this == obj)

return true;

if (obj == null)

return false;

if (getClass() != obj.getClass())

return false;

Car other = (Car) obj;

if (cost != other.cost)

return false;

if (name == null) {

return other.name == null;

} else

return name.equals(other.name);

}

}