Showing multiple information messages

[lotus18]

Hello world.

I'm trying to teach myself and I'm having trouble with this simple codes. I just want to show if the user typed the username and the password correctly, Now the problem goes like this, it displays multiple information messages if both the username and the password are incorrect or if they are both null. And also, at line 36 I'm having trouble too. Please guide me : )

String UserName = "reysean";
        String Password = "lotus18";
        boolean CheckUserName=false;
        boolean CheckPassword=false;
 
        //Check for username
        if (txtUserName.getText().isEmpty()){
            JOptionPane.showMessageDialog(null,"Please enter username.");
            CheckUserName=false;
            txtUserName.grabFocus();
        }
        else if (txtUserName.getText().equals(UserName)) {
            CheckUserName=true;
        }
        else{
            JOptionPane.showMessageDialog(null,"Please enter correct username.");
            CheckUserName=false;
            txtUserName.grabFocus();
        }
 
        //Check for password
        if (txtPassword.equals("")){
            JOptionPane.showMessageDialog(null,"Please enter password.");
            CheckPassword=false;
            txtPassword.grabFocus();
        }
        else if (txtPassword.equals(Password)) {
            CheckPassword=true;
        }
        else{
            JOptionPane.showMessageDialog(null,"Please enter correct password.");
            CheckPassword=false;
            txtPassword.grabFocus();
        }
 
        if ((CheckUserName=true) && (CheckPassword=true)){
            JOptionPane.showMessageDialog(null, "The username is: " + UserName + "\n The password is: " + Password );
        }

Rey Sean

[r035198x]

What is the purpose of the final else blocks in your chains of if-else?
e.g

          ...else{
            JOptionPane.showMessageDialog(null,"Please enter correct username.");
            CheckUserName=false;
            txtUserName.grabFocus();
        }

Is already handled by the first if part. That's why you have many messages.

For the final part, realize that
1.) == is not the same as =
2.) if you have a boolean variable called test, then
if(test == true) is the same as if(test)

[lotus18]

In VB, I can use Exit Sub for this after prompting a messages (It will exit the next line). Is there any alternative for this?

[JosAH]

In VB, I can use Exit Sub for this after prompting a messages (It will exit the next line). Is there any alternative for this?

Yes, in grown up normal programming languages we use 'return'.

kind regards,

Jos ;-)

[lotus18]

Yes, in grown up normal programming languages we use 'return'.

kind regards,

Jos ;-)

Oh I see. I've forgot to use return. Thanks JosAH.

Rey Sean

[lotus18]

Ahh.. Sorry guys, i can't still make it. I can't see this message even if both the username and password are correct.:

JOptionPane.showMessageDialog(null, "The username is: " + UserName + "\n The password is: " + Password );

Any ideas?

What I did was (As r035198x's suggestion at post #2).

 if ((CheckUserName) && (CheckPassword)){
        JOptionPane.showMessageDialog(null, "The username is: " + UserName + "\n The password is: " + Password );    
        }

Rey Sean

[r035198x]

Post the code that you have now.

[lotus18]

This is my code:

String UserName = "reysean";
        String Password = "lotus18";
        boolean CheckUserName=false;
        boolean CheckPassword=false;
 
        //Check for username
        if (txtUserName.getText().isEmpty()){
            JOptionPane.showMessageDialog(null,"Please enter username.");
            CheckUserName=false;
            txtUserName.grabFocus();
            return;
        }
        else if (txtUserName.getText().equals(UserName)) {
            CheckUserName=true;
            //goto CheckPassword;
            //txtUserName.grabFocus();
        }
        else{
            JOptionPane.showMessageDialog(null,"Please enter correct username.");
            CheckUserName=false;
            txtUserName.grabFocus();
            return;
        }
 
        //Check for password
        if (txtPassword.equals("")){
            JOptionPane.showMessageDialog(null,"Please enter password.");
            CheckPassword=false;
            txtPassword.grabFocus();
            return;
        }
        else if (txtPassword.getPassword().equals(Password)) {
            CheckPassword=true;
        }
        else{
            JOptionPane.showMessageDialog(null,"Please enter correct password.");
            CheckPassword=false;
            txtPassword.grabFocus();
            txtPassword.selectAll();
            return;
        }
 
        if ((CheckUserName) && (CheckPassword)){
        JOptionPane.showMessageDialog(null, "The username is: " + UserName + "\n The password is: " + Password );    
        }

[JosAH]

Why are people so afraid to create a few small methods? Your logic boils down
to the simple (pseudo code):

if (!(username.equals(inputUsername()) & password.equals(inputPassword())))
   showIncorrectInput();
else
   showCorrectInput();
 

Note that you should never implicitly tell a cracker that something is correct, so
the showIncorrectInput() simply shows that something was incorrect. Also note
that I used a single & instead of a double && so that no matter whether the
username was incorrect, the program still asks for a password.

Now you need to implement the following simple methods:

- inputUsername()
- inputPassword()
- showIncorrectInput()
- showCorrectInput()

I don't consider their implementation rocket science.

kind regards,

Jos

[lotus18]

Sorry for the late reply. hehe... We had just arrived from our short vacation. I did it on that way to show me how that simple program flows. Yes, you are right, the crackers must not have a hint to crack usernames and passwords. Thanks for guiding me Joash.

Rey Sean