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is there any way we can mask the value entering into jText area at runtime and should clear the contents if backspace kept pressed

I have a requirement where need to mask the value entering into jText area at runtime. I am able to achieve this but problem is scenario with backspace. When I press back space sequentially (one by one) then it work while if I kept pressing then its counting the event as one and removing only one character (by considering the key event as one key released).
Here my code snippets is :
public void showPrompt() throws InterruptedException {
sem.acquire();
this.toFront();
this.setAlwaysOnTop(true);
this.setVisible(true);
if(encryptKeystroke == true) {
jTextArea.addKeyListener(new KeyListener() {
public void keyTyped(KeyEvent e) {
}
public void keyPressed(KeyEvent e) {
}
public void keyReleased(KeyEvent e) {
if (e.getExtendedKeyCode() == KeyEvent.VK_BACK_SPACE) {
text = text.substring(0, text.length() - 1);
}
else {
text += String.valueOf(e.getKeyChar());
}
jTextArea.setText(text.replaceAll(".", "*"));
}
});
}
}
Is there any way if I kept pressing the backspace then it should remove all the characters irrespective of considering it one key event ?

As you have said in the comment that the requirements are not exactly like the password and so you won't be using JPasswordField, I would like to give a solution for the question.
Here, the code to detect a backspace key stroke is written inside the keyReleased() method. Now, the keyReleased() method will be called by the keyListener when you will pull your finger up from a key in this case your backspace key. That is why even if you continuously keep pressing the backspace key, it will execute the code only once i.e. only when you release the key.
Now, you wish to remove one character every time backspace is pressed so you can just move your code from the keyReleased() method to the keyPressed() method.
If you move the code inside the keyPressed() method, then the code will be executed at every key stroke even if you continuously keep pressing the backspace key.

Skip keyPressed event

How can i skip a keyevent if the typed key is a specific key ( in my case enter) ? When i press enter i want to click on the button and stop there, without continuing the code that comes next in this method. Seems like the "consume()" doesn't work.
public void keyPressed(KeyEvent arg0) {
if(arg0.getKeyCode() == KeyEvent.VK_ENTER && button.isDisplayable()){
button.doClick();
arg0.consume();
}}

Just stick a return statement underneath.
arg0.consume();
return;

Read the documentation on the KeyEvent. KeyEvent.consume() doesn't prevent the method from continuing to execute, it prevents any other listener method from executing due to the event.
Arrange the logic of your method so that no other code executes if the key pressed was a return key.

In Java, how to make shortcuts that similar to Emacs?

I want to know how to add shortcuts similar to Emacs's in my Java application. For example C-x C-f and C-x b.
Thanks.

Java provides a means to identify Modifier keys.
By Modifier keys I mean
Alt -- e.isAltDown();
Ctrl -- e.isControlDown();
Shift -- e.isShiftDown()
These acan be paired with other normal key press buttons from your keyboard to identify whether a combination has been pressed.
if( (e.isControlDown() && e.getKeyCode() == KeyEvent.VK_X) )
{
}
e.getModifiers() can be used to identify the modifier as well as the mouse button clicked. This returns bit mask.
See here. http://www.leepoint.net/notes-java/GUI-lowlevel/keyboard/keyboard.html
I would use it something like this for Ctrl. This is overly simplified code, but you will get an idea.
JTextField sampleTxtFld= new JTextField();
sampleTxtFld.addKeyListener(new KeyAdapter() {
public void keyPressed(KeyEvent e)
{
if((e.isControlDown() && e.getKeyCode() == KeyEvent.VK_X)
{
//identifies whether Ctrl + X has been pressed
// do some action here
}
}
public void keyReleased(KeyEvent e)
{
//some key released code here
}
public void keyTyped(KeyEvent e) {
}
});

As far as I know EMACS is an editor. If you want to change the KeyStrokes for editing command on Swing text components then you need to use Key Bindings. You can use the existing text Actions but just bind them to different KeyStrokes. See Key Bindings for a list of all the default bindings an some example of how to rebind and Action.

How to intercept keyboard strokes going to Java Swing JTextField?

The JTextField is a calculator display initialized to zero and it is bad form to display a decimal number with a leading 0 like 0123 or 00123. The numeric buttons (0..9) in a NetBeans Swing JFrame use append() [below] to drop the leading zeros, but the user may prefer the keyboard to a mouse, and non-numeric characters also need to be handled.
private void append(String s) {
if (newEntry) {
newEntry = false;
calcDisplay.setText(s);
} else if (0 != Float.parseFloat(calcDisplay.getText().toString())) {
calcDisplay.setText(calcDisplay.getText().toString() + s);
}
}

You could restrict the characters input to the JTextField by adding a custom KeyListener. Here is a quick example to demonstrate the idea:
myTextField.addKeyListener(new KeyAdapter() {
#Override
public void keyTyped(KeyEvent e) {
char c = e.getKeyChar();
if (!Character.isDigit(c)) {
e.consume(); // Stop the event from propagating.
}
}
});
Of course, you need to consider special keys like Delete and combinations like CTRL-C, so your KeyListener should be more sophisticated. There are probably even freely available utilities to do most of the grunt work for you.

You can do this with DocumentFilter.
(Edit: This answer originally included a ling to a simple complete example program on my now defunct weblog.)

Java JEditorPane

ChatGUI
im using 2 JEditorPane to transfer text from one to another.
once i have transfered the data i do the following:
JEditorPane.setText(null);
JEditorPane.setCaretPosition(0);
but as you can see from the attached image the return action makes the prompt appear a row down. how can i fix this?
EDIT: does the following seem correct to you? if so then why is caret not positioning itself to chracter 0 position?
private class MyKeyAdapter extends KeyAdapter {
#Override
public void keyPressed(KeyEvent ke) {
int kc = ke.getKeyCode();
if (kc == ke.VK_ENTER) {
System.out.println(editorPaneHistory.getText());
System.out.println(editorPaneHomeText.getText());
editorPaneHistory.setText(editorPaneHomeText.getText());
//JEditorPane - editorPaneHistory
//JEditorPane - editorPaneHomeText
editorPaneHomeText.setText(null);
editorPaneHomeText.setCaretPosition(0);
}
}
}

After your code runs, the JEditorPane is reacting to the enter key in the usual way, by inserting a newline. Try calling ke.consume() to "consume" the event so that the JEditorPane itself doesn't handle it.

Don't use a KeyListener. You should be using a custom Action. This way you can replace the default Action. Read up on Key Bindings.