public class User{
  String username;
  String keyword;

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

import java.util.ArrayList;
import java.util.Scanner;

/**
 * 登錄系統(tǒng)
 */
public class Test10 {
  public static void main(String[] args) {
    ArrayList<User> user = new ArrayList<>();
    boolean userbo = false, keybo = false;//判定是用戶名還是密碼錯誤，優(yōu)先判斷用戶名錯誤
    user.add(new User("jack", "1234"));
    user.add(new User("rose", "5678"));
    user.add(new User("tom", "0000"));//手動錄入賬號密碼
    for (int i = 0; i < user.size(); i++) {
      System.out.println(user.get(i).username + "-" + user.get(i).keyword);//輸出集合中的賬號密碼，好方便下面的debug
    }
    Scanner scanner = new Scanner(System.in);
    System.out.println("請輸入用戶名：");
    String username = scanner.nextLine();
    System.out.println("請輸入密碼：");
    String keyword = scanner.nextLine();
    for (int i = 0; i < user.size(); i++) {
      if (username.equals(user.get(i).username) == true) {
        userbo = true;
        if (keyword.equals(user.get(i).keyword) == true) {
          keybo = true;
          break;
        }
      }
    }
    System.out.print("登錄結(jié)果：");
    if (userbo == false)//根據(jù)布爾類型的變量來決定輸出什么錯誤提示
      System.out.println("沒有該用戶");
    else if (keybo == false)
      System.out.println("密碼有誤");
    else
      System.out.println("登錄成功");
  }
}