使用扫描仪在 Java 中屏蔽密码

Question

I'm a high school student learning Java and I want to know how to change input text automatically into an asterisk in Scanner. This is for a simple log-in system I have made for a project. My code is

Scanner scan = new Scanner(System.in);

   boolean correctLogin = false;
   String username;
   String password;
   String enteredUsername;
   String enteredPassword;

   while(correctLogin != true){
       System.out.println("Enter Username: ");
       enteredUsername = scan.nextLine();

       System.out.println("Enter Password: ");
       enteredPassword = scan.nextLine();

       if(enteredUsername.equals("username") && enteredPassword.equals("passw00rd")){
           System.out.println("You have entered the correct login info");
           correctLogin = true; 
           break; 
       }
       else{
           System.out.println("Your login info was incorrect, please try again");
       }
   }

    System.out.println("You are now logged in, good job!");

I want it so that when I type the password, it will automatically change into an asterisk.

Answer 1

try with this for password read:

Console console = System.console();
if(console != null){
  console.readPassword("Enter Password: ");
}

Answer 2

I also had the same issue with my console java application and I also do not want to display password in my IDE for security reasons. So, to find the bug I had to debug against the productive environment. Here is my solution that works for me in IntelliJ IDEA:

public static String getPassword() {

    String password;
    Console console = System.console();
    if (console == null) {
        password = getPasswordWithoutConsole("Enter password: ");
    } else {
        password = String.valueOf(console.readPassword("Enter password: "));
    }
    return password;
}

public static String getPasswordWithoutConsole(String prompt) {

    final JPasswordField passwordField = new JPasswordField();
    return JOptionPane.showConfirmDialog(
            null,
            passwordField,
            prompt,
            JOptionPane.OK_CANCEL_OPTION,
            JOptionPane.QUESTION_MESSAGE) == JOptionPane.OK_OPTION ? new String(passwordField.getPassword()) : "";
}

Answer 3

I am not sure if i get your question correctly, but still I will try to explain of what I understood.

To ensure that you see *** on the user screen you need to have some kind of a User interface written in HTML. I think in this case you are running your code in eclipse and via some kind of a main method. If that is the case then as Vince mentioned there is no benefit of ** since the letters would appear in the console.

What I would recommend is look for something basic web application tutorial and you would have more idea on how it works then.

HTH