HashSet去重---重写hashcode()方法与equals()方法

1.判断set中的哈希表是否已存在要添加的对象,首先调用对象的hashcode方法,得出对应的hash值.

2.如果已存在,则会调用equals()方法判断各个属性的值是否相等,若属性值全部相等,返回true,视为相同元素,不添加到Hashset.如果不相等,则会添加到Hashset.

public class Bean {
	
	private Integer id;
	private String name;
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	
	
	
	@Override
	public int hashCode() {
		// TODO Auto-generated method stub
		int hash = 0;
		hash = (id!=null?id.hashCode():0);
		hash = 31 * hash + (name!=null?name.hashCode():0);		
		return hash;
	}	
	@Override
	public boolean equals(Object obj) {
		// TODO Auto-generated method stub	
		
		if(obj !=null && obj.getClass() == Bean.class) {
			Bean bean = (Bean)obj;			
			if(this.getId() == bean.getId()&&this.getName() == bean.getName()) {
				return true;
			}			
		}
		return false;
	}

}