[SOLVED] StringTokenizer with JTextField

[keffie91]

Hello, i want to write a calculator with buttons and a JTextField. I want to use StringTokenizer to separate the two numbers and the operator.

I have tried this:

import java.awt.*;
import javax.swing.*;
import java.util.*;
public class Calculator extends JFrame {
    StringTokenizer stok = new StringTokenizer(input.getText());
    JTextField input = new JTextField();
    public Calculator(){
        Container c = getContentPane();
        
        
        setTitle("Calculator by keffie91");
        setVisible(true);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
    }
    public static void main(String[] args) {
        new Calculator();
    }

}

and like this

StringTokenizer stok = new StringTokenizer(input);

But I get the following error message: illegal forward reference.

I don't know what that mean. Is it even possible to use a JTextField with a StringTokenizer?

I have searched google but notting found.

Thanks keffie91

[Steve11235]

Handling text in this situation get complicated. Here are a couple of suggestions...

1. Use Stirng.replaceAll("regex", ""); to remove anything *except* the characters you actually want (sign, digits, decimal, operator). The regex would look *like* [^\d-\.\+/\*].

2. Use String.split("regex") to "tokenize" the input. The regex would look *like* [-/\+\*]

This will give you a String[] with the pieces. Have fun validating the input.

If you don't know about regular expressions, take the time figure them out. They're very useful, and String has several very important methods that use them.

[Eranga]

But I get the following error message: illegal forward reference.

That error message means you have use a variable before use.

In your code have something like this.

    StringTokenizer stok = new StringTokenizer(input.getText());
    JTextField input = new JTextField();

You have initialize the variable input in the second line, that's why you get the error. Interchange that two lines as follows. Compile it, you don't have that error.

    JTextField input = new JTextField();
    StringTokenizer stok = new StringTokenizer(input.getText());

Is it even possible to use a JTextField with a StringTokenizer?

Form the JTextField you must get the string first of all. On that string you can apply the StringTokernizer. But I'm not advice to use it, mess on Java. Better to use regular expression.

Can you more clearly explain what you want to do on a string?

[keffie91]

I want to seperate the operator and the numbers and do a calculation.

Thanks

keffie91

[Eranga]

What operator you want to use for separation. How looks like your input string? Did you read that Steve11235s' last post?

[keffie91]

the operator can be: * \ + -

the input strong looks like : number1 operator number2

And yes i have read Steve11235s' post.

[Eranga]

So you have the solution with you right?

[keffie91]

I have no time to try now. I'm very bizzy. But i think it's enough.

Thanks keffie91