java - 通过命令行使用用户输入 java 进行基本登录无法正常工作

Question

所以我有一个非常非常基本的登录程序，当您输入正确的凭据时，它只会打印一行。即使我输入正确的凭据，它所做的只是从 if else 语句中打印错误消息。任何帮助将不胜感激。

import java.util.Scanner;

public class Exercise4
{
private static String Username = "javacave";
private static String Password = "welcome1";

public static void main(String[] args)
{
    System.out.println("Please enter username");
    Scanner in = new Scanner(System.in);
    String UN = in.nextLine();

    System.out.println("Please enter password");
    Scanner inn = new Scanner(System.in);
    String PW = inn.nextLine();

    if (UN == Username && PW == Password)
    {
        System.out.println("User has logged in successfully!");
    }
    else {
        System.out.println("You have entered the wrong credentials, please try again.");
    }
}
 }

Answer 1

(UN == Username && PW == Password)

应该是:

(UN.equals(Username) && PW.equals(Password))

<小时/>

每当您比较两个字符串时，请使用 equals() 来检查值的相等性，而不是使用 == 来检查两个引用是否相同内存中。

请阅读 Code Conventions for the Java Programming Language .