为什么case :6比较时会报错?

[浪奔的小三爷]

package test3;

public class Employee implements Comparable<Employee>{
	private int ID;private String name;private char sex;
	private int age; private int salary;
	public Employee(int ID,String name,char sex,int age,int salary) {
		this.ID = ID;
		this.name = name;
		this.sex = sex;
		this.age = age;
		this.salary = salary;
	}
	public int getID() {
		return ID;
	}
	public String getName() {
		return name;
	}
	public char getSex() {
		return sex;
	}
	public int getAge() {
		return age;
	}
	public int getSalary() {
		return salary;
	}
	public String toString() {
		return ID+","+name+","+sex+","+age+","+salary;
	}
	@Override
	public int compareTo(Employee o) {
		if(this.salary>o.salary) {
			return 1;
		}else if(this.salary<o.salary) {
			return -1;
		}
		return 0;
	}
}

package test3;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;

public class ExampleMap {
	HashMap<Integer,Employee> hmap = new HashMap();
	public void addEmployee(Employee e) {
		hmap.put(e.getID(), e);
	}
	public String getEmployee(int id) {
		Employee e = null;
		for(Integer key:hmap.keySet()) {
			if(key==id) {
				e = hmap.get(key);
			}
		}
		return e.toString();
	}
	public  void deleteEmployee(int id) {
		for(Integer key:hmap.keySet()) {
			if(key==id) {
				hmap.remove(key);
			}
		}
	}
	public void updateEmployee(Employee e) {
		for(Integer key:hmap.keySet()) {
			if(key==e.getID()) {
				hmap.put(key,e);
			}
		}
	}
	public void showAllEmployee() {
		for(Integer key:hmap.keySet()) {
			System.out.println(hmap.get(key).toString());
		}
	}
	public void sortBySalary() {
		List list = new ArrayList(hmap.entrySet());
		Collections.sort(list);
		for(Integer key:hmap.keySet()) {
			System.out.println(hmap.get(key).toString());
		}
	}
}

package test3;

import java.util.Scanner;
public class test {
	public static void main(String[] args) {
		ExampleMap em = new ExampleMap();
		while(true) {
			System.out.println("******雇员管理系统******");
			System.out.println("1.添加雇员");
			System.out.println("2.显示所有雇员信息");
			System.out.println("3.根据雇员ID号查找雇员");
			System.out.println("4.修改雇员信息");
			System.out.println("5.根据雇员id号删除雇员");
			System.out.println("6.按薪水排序");
			System.out.println("7.退出");
			System.out.println("********************");
			System.out.println("请输入编号:");
			Scanner sc = new Scanner(System.in);
			int bh = sc.nextInt();
			switch(bh) {
			case 1:
				System.out.println("您选择了添加雇员");
				System.out.println("请输入id号:");
				int ID = sc.nextInt();
				System.out.println("请输入姓名:");
				String name = sc.next();
				System.out.println("请输入性别:");
				char sex = sc.next().charAt(0);
				System.out.println("请输入年龄:");
				int age = sc.nextInt();
				System.out.println("请输入薪水:");
				int salary = sc.nextInt();
				Employee e = new Employee(ID,name,sex,age,salary);
				em.addEmployee(e);
				break;
			case 2:
				System.out.println("您选择了显示所有雇员信息");
				em.showAllEmployee();
				break;
			case 3:
				System.out.println("你选择了根据雇员ID查找雇员");
				System.out.println("请输入您要查找的id号:");
				ID = sc.nextInt();
				em.getEmployee(ID);
				break;
			case 4:
				System.out.println("请输入雇员信息:");
				System.out.println("请输入id号:");
			    ID = sc.nextInt();
				System.out.println("请输入姓名:");
				name = sc.nextLine();
				System.out.println("请输入性别:");
				sex = sc.next().charAt(0);
				System.out.println("请输入年龄:");
				age = sc.nextInt();
				System.out.println("请输入薪水:");
				salary = sc.nextInt();
				e = new Employee(ID,name,sex,age,salary);
				em.updateEmployee(e);
				break;
			case 5:
				System.out.println("请输入您要删除的id号:");
				ID = sc.nextInt();
				em.deleteEmployee(ID);
				break;
			case 6: 
				em.sortBySalary();
			case 7:
				return;
			}
		}
	}
}

[得一以生]

报啥错，应该不会报错啊

[一般的俗]

sortBySalary() 里面， hmap.entrySet() 返回的是一个 Set集合 Set<Map.Entry<Integer, Employee>> ，下面循环你拿的又是 hmap.keySet() 把 List list = new ArrayList(hmap.entrySet()) 改成 ==> List list = new ArrayList(hmap.keySet());

[=PNZ=BeijingL]

sortBySalary() 里面， hmap.entrySet() 返回的是一个 Set集合 Set<Map.Entry<Integer, Employee>> ，下面循环你拿的又是 hmap.keySet()
把 List list = new ArrayList(hmap.entrySet()) 改成 ==> List list = new ArrayList(hmap.keySet());


楼主的Employee实现了接口 Comparable ，实现用salary 排序， 并不是想用KEY 排序

[=PNZ=BeijingL]

我觉得修改方式应该是

List list = new ArrayList(hmap.entrySet()) //hmap.entrySet()返回的是Set<Map.Entry<Integer, Employee>> 不能比较
修改成 List list = new ArrayList(hmap.values()); //hmap.values() 返回的是值集合Collection

[一般的俗]

引用 6 楼 PNZ.BeijingL 的回复:

我觉得修改方式应该是 List list = new ArrayList(hmap.entrySet()) //hmap.entrySet()返回的是Set<Map.Entry<Integer, Employee>> 不能比较 修改成 List list = new ArrayList(hmap.values()); //hmap.values() 返回的是值集合Collection

哈哈哈，大兄弟说的对，没仔细看

[Gemini_Kanon]

贴下报错信息撒

[浪奔的小三爷]