How can I supress keycode?

[cjmartin]

For my application we use scan guns to scan barcodes to do various things. My issue is with tabbing. We scan a barcode that represents the ">" sign. When focus is on the combobox box and they scan the ">" sign it places the ">" in the combobox. How can I keep this from displaying? Is there a way to supress the keycode or some other method? I have used the e.consume and the SwingUtilities.invokeLater methods as they have worked in the past, but not working here. I have also tried to save the value of the item selected in the combobox and then selecting it again at the end based on the selectedindex.

Here is a demo of my issue:

import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;

import javax.swing.DefaultComboBoxModel;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;


import org.dyno.visual.swing.layouts.Constraints;
import org.dyno.visual.swing.layouts.GroupLayout;
import org.dyno.visual.swing.layouts.Leading;

//VS4E -- DO NOT REMOVE THIS LINE!
public class TestB extends JFrame {

	private static final long serialVersionUID = 1L;
	private JComboBox fromComboBox;
	private JTextField jTextField0;
	//private JButton okButton;
	private static final String PREFERRED_LOOK_AND_FEEL = "javax.swing.plaf.metal.MetalLookAndFeel";

	public TestB() {
		initComponents();
	}

	private void initComponents() {
		setLayout(new GroupLayout());
		add(getJComboBox0(), new Constraints(new Leading(83, 148, 10, 10), new Leading(56, 10, 10)));
		add(getJTextField0(), new Constraints(new Leading(85, 136, 10, 10), new Leading(109, 29, 10, 10)));
		//add(getJButton0(), new Constraints(new Leading(105, 10, 10), new Leading(185, 10, 10)));
		setSize(320, 240);
	}

	private JTextField getJTextField0() {
		if (jTextField0 == null) {
			jTextField0 = new JTextField();
			jTextField0.setText("jTextField0");
		}
		return jTextField0;
	}

	private JComboBox getJComboBox0() {
		if (fromComboBox == null) {
			fromComboBox = new JComboBox();
			fromComboBox.setEditable(true);
			fromComboBox.setModel(new DefaultComboBoxModel(new Object[] { "" }));
			fromComboBox.setDoubleBuffered(false);
			fromComboBox.setBorder(null);
			fromComboBox.addItem("oranges");
			fromComboBox.addItem("lemons");
			fromComboBox.addItem("limes");
			
			fromComboBox.getEditor().getEditorComponent().
			addKeyListener(new KeyAdapter() {
	
				public void keyPressed(KeyEvent event) {
					fromComboBoxKeyKeyPressed(event);
				}
			});
		}
		return fromComboBox;
	}

	private static void installLnF() {
		try {
			String lnfClassname = PREFERRED_LOOK_AND_FEEL;
			if (lnfClassname == null)
				lnfClassname = UIManager.getCrossPlatformLookAndFeelClassName();
			UIManager.setLookAndFeel(lnfClassname);
		} catch (Exception e) {
			System.err.println("Cannot install " + PREFERRED_LOOK_AND_FEEL
					+ " on this platform:" + e.getMessage());
		}
	}

	
	public static void main(String[] args) {
		installLnF();
		SwingUtilities.invokeLater(new Runnable() {
			@Override
			public void run() {
				TestB frame = new TestB();
				frame.setDefaultCloseOperation(TestB.EXIT_ON_CLOSE);
				frame.setTitle("TestCancelKeyStroke");
				frame.getContentPane().setPreferredSize(frame.getSize());
				frame.pack();
				frame.setLocationRelativeTo(null);
				frame.setVisible(true);
			}
		});
	}
	
	private void fromComboBoxKeyKeyPressed(KeyEvent e) {
		final int num = fromComboBox.getItemCount();
		Boolean bScroll = new Boolean(true);
		
		//This checks for the key that is scanned to Tab to the 
                          //next field. It is the > sign.
		if ((e.getKeyCode() == 46) && (e.isShiftDown())) {
			SwingUtilities.invokeLater(new Runnable() {
				public void run() {
					jTextField0.requestFocus();
				}
			});
			e.consume();
		}
	}
	
}

[Fubarable]

Hm, not sure if this will work every time, but one possible solution is to extract the document from the combo box's editor and use a document filter like so:

   private JComboBox getJComboBox0() {
      if (fromComboBox == null) {
         fromComboBox = new JComboBox();
         fromComboBox.setEditable(true);
         fromComboBox.setModel(new DefaultComboBoxModel(new Object[]{""}));
         fromComboBox.setDoubleBuffered(false);
         fromComboBox.setBorder(null);
         fromComboBox.addItem("oranges");
         fromComboBox.addItem("lemons");
         fromComboBox.addItem("limes");

         JTextField cEditor = (JTextField) fromComboBox.getEditor().getEditorComponent();
         PlainDocument doc = (PlainDocument) cEditor.getDocument();
         doc.setDocumentFilter(new DocumentFilter() {
            @Override
            public void insertString(FilterBypass fb, int offset, String string, AttributeSet attr)
                     throws BadLocationException {
               if (string.equals(">")) {
                  jTextField0.requestFocus();
               }
               else {
                  super.insertString(fb, offset, string, attr);
               }
            }
            
            @Override
            public void replace(FilterBypass fb, int offset, int length, String text,
                     AttributeSet attrs) throws BadLocationException {
               if (text.equals(">")) {
                  jTextField0.requestFocus();
               } else {
                  super.replace(fb, offset, length, text, attrs);
               }
            }
         });
         
      }
      return fromComboBox;
   }

[berkeleybross]

You may want to look at this tutorial

You should assign a key binding to each field, and you want the action to be field.transferFocus();

e.g. (code not tested)

        Action changeFocus = new AbstractAction() {
            public void actionPerformed(ActionEvent e) {
                comboBox.transferFocus();
            }
        };
        
        KeyStroke keyStroke = KeyStroke.getKeyStroke('>');
        comboBox.getInputMap(JComponent.WHEN_FOCUSED).put(keyStroke, "changeFocus");
        comboBox.getActionMap().put("changeFocus", changeFocus);

Alternatively, you could use a keylistener but i think its not recomended for some reason :S

Hope this helps,
berkeleybross

[cjmartin]

Fubarable....this seems to be working for me. Thanks for the solution. Now this works for comboboxes. What about jtextfields? I am having the same problem where the scanned character is displaying in the field. Thanks!

[cjmartin]

Also to clarify, there are different characters that can be scanned to emulate different actions. Such as Tab and Backspace. And they can be on jtextfields or jcombobox.

[Fubarable]

Fubarable....this seems to be working for me. Thanks for the solution. Now this works for comboboxes. What about jtextfields? I am having the same problem where the scanned character is displaying in the field. Thanks!

Yes, of course it will work for JTextFields as this was adapted from a technique commonly used on JTextFields, the DocumentFilter. Again, you'll have to extract the JTextField's Document and cast it to a PlainDocument. For more details, please see the Sun tutorial on using DocumentFilters. Luck.

[cjmartin]

Thanks everyone. With your code examples I was able to fix my issue with supressing the keystrokes.

[Fubarable]

Glad you've got ti working! You'll want to mark this thread "Solved" in the thread tools at the top.