引用

public class Test {
    public static void main(String[] args) {
        /*
         * 将一个对象加入一个集合中，集合中的对象与原对象指向的是同一个引用
         */
        HashMap<String, Obj> map = new HashMap<String, Obj>();
        Obj obj = new Obj("wanghui");
        map.put("wanghui", obj);
        System.out.println(map.get("wanghui").getName());//wanghui
        obj.setName("wangqiang");
        System.out.println(map.get("wanghui").getName());//wangqiang
        
        ArrayList<Obj> list = new ArrayList<>();
        list.add(obj);
        System.out.println(list.get(0).getName());//wangqiang
        obj.setName("wanghui");
        System.out.println(list.get(0).getName());//wanghui
    }
}
class Obj{
    private String name;
    public Obj(String name){
        this.name = name;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    
}