控制台输入若干个学生的姓名及所在系，并统计各系的学生人数并输出各系人数及姓名Java

代码如下：

import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        Map<String, Integer> departmentMap = new HashMap<>();
        while (true) {
            System.out.print("请输入学生的姓名及所在系（以空格分隔，输入exit结束）：");
            String input = scanner.nextLine();
            if (input.equals("exit")) {
                break;
            }
            String[] inputs = input.split(" ");
            if (inputs.length != 2) {
                System.out.println("输入格式错误，请重新输入！");
                continue;
            }
            String name = inputs[0];
            String department = inputs[1];
            if (departmentMap.containsKey(department)) {
                departmentMap.put(department, departmentMap.get(department) + 1);
            } else {
                departmentMap.put(department, 1);
            }
        }
        System.out.println("各系人数及姓名如下：");
        for (Map.Entry<String, Integer> entry : departmentMap.entrySet()) {
            String department = entry.getKey();
            int count = entry.getValue();
            System.out.println(department + "：" + count + "人");
        }
    }
}

运行截图如下：