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Thread: Jtextfield Validation

  1. #1
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    Default Jtextfield Validation

    Hi all

    In my Swing application i am using Jtextfields.If Jtextfield have empty string("") i need to set it to 0 always .Is there any easy way to set this without if else comparison.

    Thanks

    Nimish


  2. #2
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    Default Re: Jtextfield Validation

    Why dont you try JFormattedTextField instead?

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    Default Re: Jtextfield Validation

    hi relixus
    i am newbie here. Can u give me some example how to use JFormattedTextfield for this.

    Thanks

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    Default Re: Jtextfield Validation

    Why can't you use if/else?

    Just to clarify, if the text is deleted out of the textfield, you want it to automatically update to 0?
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    Default Re: Jtextfield Validation

    Hello PF
    Really thats i want .. I want to automatically updated into 0.

    Thanks

  6. #6
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    Default Re: Jtextfield Validation

    Does this need to check in real-time? When the user is typing/deleting text from the field or does it check when a button is pressed?
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    Default Re: Jtextfield Validation

    Hi PF

    i need to check in when the user is typing/deleting. Plz help me to find a solution ,,Thanks

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    Default Re: Jtextfield Validation

    Have a play with this code:

    import java.awt.*;
    import java.awt.event.*;
    import javax.swing.*;
    import javax.swing.event.*;
    import javax.swing.text.*;
     
    public class TextValidation {
     
    	/**
    	 * JavaProgrammingForums.com
    	 */	
    	public static MyTextField t = new MyTextField(16);
     
    	public static void main(String[] a) {
     
    		JFrame f = new JFrame("JAVA FORUMS");
    		f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    		//MyTextField t = new MyTextField(16);
    		t.setText("0");
    		f.getContentPane().add(t, BorderLayout.CENTER);
    		f.pack();
    		f.setVisible(true);
    	}
     
    	private static class MyTextField extends JTextField implements
    			ActionListener, DocumentListener {
     
    		public MyTextField(int l) {
    			super(l);
    			addActionListener(this);
    			Document doc = this.getDocument();
    			doc.addDocumentListener(this);
    		}
     
    		//Enter key pressed
    		public void actionPerformed(ActionEvent e) {
    			//System.out.println(getText());
    		}
     
    		//Text inserted
    		public void insertUpdate(DocumentEvent e) {
    			//System.out.println(getText());
    		}
     
    		//Text deleted
    		public void removeUpdate(DocumentEvent e) {
    			//System.out.println(getText());
    			if(getText().equals("")){
    				System.out.println("IM BLANK!");
    			}
    		}
     
    		public void changedUpdate(DocumentEvent e) {
    			//System.out.println(getText());
    		}
     
    	}
    }
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    Default Re: Jtextfield Validation

     public void removeUpdate(DocumentEvent e) {
                //System.out.println(getText());
                if(getText().equals("")){
                  setText("0");
                }
            }

    I tried the above .But i got Exception in thread "AWT-EventQueue-0" java.lang.IllegalStateException: Attempt to mutate in notification.I Google it. Using DoucmentFilter may slove the problem.

    public class Doc extends DocumentFilter {
        public void insertString(FilterBypass fb, int offset, String string, AttributeSet attr) throws BadLocationException
        {
     
            super.insertString(fb, offset, string, attr);
        }
     
          public void remove(FilterBypass fb, int offset, int length) throws BadLocationException
        {
    //    
     
            super.remove(fb, offset, length);
           if(fb.getDocument().getLength()==0)
           {
               insertString(fb, offset, "0", null);
     
           }
     
        }
        public void replace(FilterBypass fb, int offset, int length, String text, AttributeSet attrs) throws BadLocationException
        {
    //      super.replace(fb, offset, length, text, attrs);
             if(fb.getDocument().getText(0, 1).equals("0"))
            {
                remove(fb, 0, 1);
            }
     
        }
    }

    But dont know it's the exact way of doing this .Plz let me know if u have any suggestions.

    Thanks

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