Need help with a gui program

[coderX]

Hi,im new to java gui programming
I want to create a loop to display numbers(for example:1 to 20) inside jTextField.
Here is what I tried:

 private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
        // TODO add your handling code here:
        int i =1;
        int x;
       while (i<=20) {
         x= (Integer.parseInt(jTextField1.getText())+1);
        jTextField1.setText(jTextField1.getText()+ x);
        i++;
       }
    }

Thank you

[pbrockway2]

What happened when you tried that?

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Consider using more descriptive variables and methods than jTextField1 and jButton1ActionPerformed(). As the amount of code increases there is a very real payoff from having variables and methods say, by their very text, what they are and do.

[coderX]

This is my program:

When I type 1 into the textfield,I expect it to display numbers from 1 to 20,but what I get is: 1213121412131215

[Fubarable]

If you walk through your code in your head, you'll see that the output you see is what you should expect. Do you know that the + operator has different meanings if you're dealing with Strings vs. numbers, and your method above uses it for both situations, numeric addition and String concatenation.

[coderX]

ok,could you please help me to get the expected result?

[Fubarable]

Let's see what you're doing, but I'm going to split some of the code up for clarity (and you might wish to do this yourself in future code):

while (i<=20) {
  // to replace the line:
  // x= (Integer.parseInt(jTextField1.getText())+1);
  String textFieldText = jTextField1.getText(); // self explanatory
  int x = Integer.parseInt(textFieldText); // self explanatory
  x = x + 1; // A)


  // to replace the line:
  // jTextField1.setText(jTextField1.getText()+ x);
  String newText = jTextField1.getText();  // B)
  newText = newText + x;  // C)
  jTextField1.setText(newText); //D)
  i++; // self explanatory
}

So what's going on?

1. If the textfield initially holds 1, at this point x will hold 2 -- and this is what you want, I think.
2. You're getting the String that is held in the JTextField which at this point is "1"
3. You're doing String concatenation with the textfield's String and x. "1" + 2 = "12"
4. You're setting the JTextField with this new String, "12".

So the solution is not to do String concatenation. You should be able to change your code I think to try to improve it. Please give it a go, and see what you can come up with.

Next we may have to talk about Swing Timers, but let's solve this problem first.

[coderX]

I just looked into it today and found out the mistake I made,^Thank you :)
Here is what I did:

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
       // TODO add your handling code here:
       int i =0;
       int x=1;
      while (i<=20) {
       jTextField1.setText(jTextField1.getText()+"  " +  x);
       x++;
       i++;
      }
   }

[DarrylBurke]

Hi,im new to java gui programming

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {

'New to GUI programming' doesn't go well with using a visual designer and code generator.

db