Map的简单使用。

    @Test
    //输出Java类型。
    public  void save() {
      Map map = new HashMap();
        map.put("Key1","Value1");
        map.put("Key2","Value2");
        map.put("Key3","Value3");
        map.put("Key4","Value4");
        for(Map.Entry entry : map.entrySet()){
            System.out.println("Key是：  "+entry.getKey()+"    value是："+entry.getValue());
        }

    }

//创建一个实体类
public class User {
    private String username;
    private String password;

    public User(String username, String password) {
        this.username = username;
        this.password = password;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public String toString() {
        return "User{" +
                "username='" + username + ''' +
                ", password='" + password + ''' +
                '}';
    }
}


//测试：
    //自定义输出实体类
    @Test
    public void save1(){
       Map map =  new HashMap();
        map.put("1",new User("username1","password1"));
        map.put("2",new User("username2","password2"));
        map.put("3",new User("username3","password3"));
        map.put("4",new User("username4","password4"));

        for (Map.Entry maps : map.entrySet()) {
            System.out.println("key是： " + maps.getKey()+"   value是：  "+maps.getValue());
        }
    }