How can I know when the key typed change my text? Or if the key is a char?
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1What text? Is it in a text field, text area, etc? How are you listening? Do you only care if the key pressed is in a text area, or only if it isn't? A little more about what you are trying to accomplish from listening for the key press would help as well. – aperkins Jul 28 '10 at 17:21
3 Answers
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The interface KeyListener contain three methods:
void keyTyped(KeyEvent)
void keyPressed(KeyEvent)
void keyReleased(KeyEvent)
So, if you get the char in the KeyEvent object like:
if ("a".equals(KeyEvent.getKeyChar()))
System.out.println("It's a letter")
Agusti-N
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i guess you want to know wether typing a specific key actually prints a char or is some "invisible" control character or something:
in this case you can check the typed key in the KeyEvent which gets passed into the implemented methods of the KeyListener:
this quick example should work, although i didnt test it. It constructs a new String on the char returned by the KeyEvent, than invokes the length() method to chekc if the char created a readable character in the String. kinda hacky but i hope you get the gist of it
public void keyReleased(KeyEvent ke){
if (new String(ke.getKeyChar()).length() == 0){
// do something important...
}
}
alternativley you can use ke.getKeyCode() and check vs the static fields in KeyEvent (VK_F12,VK_ENTER...)
check here:
http://docs.oracle.com/javase/6/docs/api/java/awt/event/KeyEvent.html
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It doesn't work! :( When I create the string after backspace, the value is "\b", what means length equals 1. – Victor Jul 28 '10 at 17:40
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reading the javadoc yielded that getKeyCode()==KeyEvent.VK_UNDEFINED should work... – fasseg Jul 28 '10 at 18:05
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You need a document listener. See the oracle docs for more information: How to Write a Document Listener
