Map

public class Emp {
    private String e_id;
    private String e_name;

    public Emp(String e_id, String e_name) {
        this.e_id = e_id;
        this.e_name = e_name;
    }

    public String getE_id() {
        return e_id;
    }

    public void setE_id(String e_id) {
        this.e_id = e_id;
    }

    public String getE_name() {
        return e_name;
    }

    public void setE_name(String e_name) {
        this.e_name = e_name;
    }

}

import java.util.*;

public class MapText {

    public static void main(String[] args) {
        Map<String,String> map = new HashMap<>();
        Emp emp = new Emp("001", "张三");
        Emp emp1 = new Emp("002", "李四");
        Emp emp2 = new Emp("005", "王五");
        Emp emp3 = new Emp("006", "马六");
        map.put(emp.getE_id(), emp.getE_name());
        map.put(emp1.getE_id(), emp1.getE_name());
        map.put(emp2.getE_id(), emp2.getE_name());
        map.put(emp3.getE_id(), emp3.getE_name());

        System.out.println("HashMap类实现的map集合，无序：");
        for (String str : map.keySet()) {
            System.out.println(str + ":" + map.get(str));
        }
        System.out.println("HashMap类实现的map集合，有序：");
        TreeMap<String,String> tmap = new TreeMap<>();
        tmap.putAll(map);
        for (String str : tmap.keySet()) {
            System.out.println(str + ":" + tmap.get(str));
        }

        map.remove("005");
        System.out.println(map);
        tmap.remove("005");
        System.out.println(tmap);
    }

}

运行：