IN JAVA swing textbox only accept numeric values and one time ( +, - , . )

Question

/* I m trying to make a TEXTBOX using Java/eclipse. textbox only accept numeric values via keybord and that's have using swing + sing "single time" at "first position" - sing "single time" at "first position" . period "single time" at "any position" and delete and backspace work perfectely */

import javax.swing.*;  
import java.awt.event.KeyEvent;  
import java.awt.event.KeyListener;  

public class NumericBox extends JApplet{ 
    //making textfield
    static JTextField tf = new JTextField();  
    //main start
    public static void main(String arh[]){  

        NumericBox g = new NumericBox();  
        Handle h = g.new Handle();  
        JFrame f = new JFrame();  //frame
        JPanel p = new JPanel();  //pannel

        tf.setColumns(5);  
        tf.addKeyListener(h);  

        p.add(tf);    
        f.add(p);  
        f.setSize(200,100);  
        f.setVisible(true);  

    }//end of main method  
   // to use only numaric key implementation

    private class Handle implements KeyListener{  

        public void keyTyped(KeyEvent e) {
            char vChar = e.getKeyChar();
            if (!(Character.isDigit(vChar)
                  || (vChar == KeyEvent.VK_BACK_SPACE)
                  || (vChar == KeyEvent.VK_CLEAR)
                  || (vChar == KeyEvent.VK_PERIOD)
                  || (vChar == KeyEvent.VK_PLUS)
                  || (vChar == KeyEvent.VK_MINUS))) {
                getToolkit().beep();
                e.consume();
            }

       /*    if(vChar == KeyEvent.VK_PERIOD){
                            if(i==1)
                                e.consume();
                            else
                                i=1;
                        }
         */ 
        }

        public void keyPressed(KeyEvent e) {}  //keyPressed  events
        public void keyReleased(KeyEvent e) {}  //keyReleased events

    }//end of inner class  

}//end of outer class

Trying to do that by filtering key events is a fragile approach (think about pasting to the field, for instance). Take a look at the answers [here](http://stackoverflow.com/questions/5662651/how-to-implement-in-java-jtextfield-class-to-allow-entering-only-digits), for example. — kiheru, Jan 07 '15 at 16:41
+ sing "single time" at "first position" - sing "single time" at "first position" . period "single time" at "any position" not working only in my code +,-,. are repated and +,- are on diff-diff pos that is wrong — abhinav, Jan 07 '15 at 16:56
Use a DocumentFilter, and test for `Double.parseDouble(...)` within it. See [link](http://stackoverflow.com/questions/12793030/jtextfield-limiting-character-amount-input-and-accepting-numeric-only) for details. — Hovercraft Full Of Eels, Jan 07 '15 at 22:27

score 0 · Answer 1 · edited May 23 '17 at 11:57

0

Validating your text would be handled best via a regular expression. As for catching the value changes, go for the underlying document provided by Swing, following the example here: https://stackoverflow.com/a/3953219/1843508

edited May 23 '17 at 11:57

Community

1
1

answered Jan 07 '15 at 17:03

Ofer Lando

814
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Voqus · Answer 2 · 2015-01-07T22:35:38.777

0

You can either use JFormattedTextField or as @Ofer Lando said, using regex(regular expression)

Example,

private boolean containsNumber(String sentence)
{
    Pattern patt = Pattern.compile(".*?[0-9].*");
    Matcher m = patt.matcher(sentence);
    return m.matches();
}

edited Jan 07 '15 at 22:35

answered Jan 07 '15 at 22:22

Voqus

159
1
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IN JAVA swing textbox only accept numeric values and one time ( +, - , . )

2 Answers2