Editable JComboBox that must accept only alphabets

[sandy]

Hi
How can a editable JComboBox made to accept only Lowercase and Uppercase Alphabets ? Any suggestions ?
Sandy
:roll:

[Rene Liebmann]

Hi,
I see two possibilities. The easier one is to check, when actionPerformed event is fired, which element of the combobox is selected. Then you have a string and you can parse every single character, if it is a right one.
The second possibility I see, you need to register a KeyListener to the editor of the ComboBox. To get this, you need to call:
JComboBox.getEditor().getEditorComponent();
Then you catch every keyTyped event and you ask for a correct input.
Hope this helps
Rene

[sandy]

Hi Rene
Thanks a lot for the suggestion, but my query was if the user types in some string, how can the ComboBox prevent him from typing the wrong characters i.e the validation should be correct only for Alphabets, something of what a PlainDocument does for the TextField validation.Since ComboBox does'nt validate for Key events, how can this be achieved ?
Regards
Sandhya

[Rene Liebmann]

Hi,
here is a little test:

  
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.JTextComponent;

public class ComboBoxValidation extends JFrame {
  GridBagLayout gridBagLayout1 = new GridBagLayout();
  JComboBox jComboBox1 = new JComboBox();
  public ComboBoxValidation() {
    try {
      jbInit();
    }
    catch(Exception e) {
      e.printStackTrace();
    }
  }
  public static void main(String[] args) {
    ComboBoxValidation comboBoxValidation1 = new ComboBoxValidation();
    comboBoxValidation1.setSize(300,300);
    comboBoxValidation1.show();
  }
  private void jbInit() throws Exception {
    this.getContentPane().setLayout(gridBagLayout1);
    jComboBox1.setEditable(true);
    this.getContentPane().add(jComboBox1, new GridBagConstraints(0, 0, 1, 1, 0.0, 0.0
            ,GridBagConstraints.CENTER, GridBagConstraints.NONE, new Insets(0, 0, 0, 0), 0, 0));
    this.jComboBox1.getEditor().getEditorComponent().addKeyListener(new CbKeyListener(jComboBox1));
  }
  private class CbKeyListener implements KeyListener{
    private JComboBox comboBox;
    public CbKeyListener(JComboBox box){
      comboBox = box;
      System.out.println("A = "+KeyEvent.VK_A);
      System.out.println("Z = "+KeyEvent.VK_Z);
    }
    public void keyReleased(KeyEvent e){
      System.out.println(e.getKeyCode()+ " = "+e.getKeyChar());
      if (e.getKeyCode() == KeyEvent.VK_SHIFT) return;
      if (e.getKeyCode() == KeyEvent.VK_CAPS_LOCK) return;
      if (e.getKeyCode() == KeyEvent.VK_SPACE) return;
      if (e.getKeyCode()>=KeyEvent.VK_A && e.getKeyCode()<=KeyEvent.VK_Z){
        return;
      }
      JTextComponent text = (JTextComponent)this.comboBox.getEditor().getEditorComponent();
      String str = (String)text.getText();
      str = str.substring(0,str.length()-1);
      text.setText(str);
    }
    public void keyPressed(KeyEvent e){}
    public void keyTyped(KeyEvent e){}
  }
}

Is this what you want?

[sandy]

Hi Rene
Thanks a lot ! It worked and yeah, this is what I wanted. Thanks again!!
Sandhya

[Nathan Pruett]

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