issue with implementation of keyListener for writting unicode (Sindhi) in java

Question

I want to use unicode through the implementation of keyListener on jTextField in this way :

textField.addKeyListener(new KeyListener() {

        @O         


        

Answer 1

Use a DocumentFilter.

By the time the KeyListener recives the event, the character has already being added to the field.

Also KeyListener won't deal with the user pasting content into the field

Answer 2

Regardless of your current problem, you shouldn't be using a KeyListener in a JTextField. Use a DocumentListener or DocumentFilter instead. Given your code, I'm guessing that a DocumentFilter is what you need, since you wish to change the text of the JTextField as it is being entered and before it is being displayed.

e.g.,

import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.DocumentFilter;
import javax.swing.text.PlainDocument;

public class SwapAForAleph {
   // No idea of the correct unicode for this!!!
   public static final char SINDHI_ALIF = '\u0623'; 

   public static void main(String[] args) {
      final JTextField textField = new JTextField(10);
      textField.setFont(textField.getFont().deriveFont(32f));
      PlainDocument doc = (PlainDocument) textField.getDocument();
      doc.setDocumentFilter(new DocumentFilter() {
         @Override
         public void insertString(FilterBypass fb, int offset, String text,
               AttributeSet attr) throws BadLocationException {
            text = filterText(text);
            super.insertString(fb, offset, text, attr);
         }

         @Override
         public void replace(FilterBypass fb, int offset, int length,
               String text, AttributeSet attrs) throws BadLocationException {
            text = filterText(text);
            super.replace(fb, offset, length, text, attrs);
         }


         private String filterText(String text) {
            return text.replace('a', SINDHI_ALIF);
         }
      });

      JPanel panel = new JPanel();
      panel.add(textField);
      JOptionPane.showMessageDialog(null, panel);
   }
}

Or looked at in another way...

import java.awt.ComponentOrientation;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingConstants;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.DocumentFilter;
import javax.swing.text.PlainDocument;

public class NonEnglishTextField {
   public static final char ALEPH = '\u05D0';

   public static void main(String[] args) {
      final JTextField textField = new JTextField(20);
      textField.setFont(textField.getFont().deriveFont(32f));
      textField.setComponentOrientation(ComponentOrientation.RIGHT_TO_LEFT);
      textField.setHorizontalAlignment(SwingConstants.RIGHT);
      PlainDocument doc = (PlainDocument) textField.getDocument();
      doc.setDocumentFilter(new DocumentFilter() {
         @Override
         public void insertString(FilterBypass fb, int offset, String text,
               AttributeSet attr) throws BadLocationException {
            text = filterText(text);
            super.insertString(fb, offset, text, attr);
         }

         @Override
         public void replace(FilterBypass fb, int offset, int length,
               String text, AttributeSet attrs) throws BadLocationException {
            text = filterText(text);
            super.replace(fb, offset, length, text, attrs);
         }


         private String filterText(String text) {
            StringBuilder sb = new StringBuilder();
            for (char c : text.toLowerCase().toCharArray()) {
               if (c >= 'a' && c <= 'z') {
                  char newChar = (char) (c - 'a' + ALEPH);
                  sb.append(newChar);
               } else {
                  sb.append(c);
               }
            }
            return sb.toString();
         }
      });

      JPanel panel = new JPanel();
      panel.add(textField);
      JOptionPane.showMessageDialog(null, panel);
   }
}