java eclipse windowbuilder keyPressed event does not fire -

i've got problem program can't solve. i'm trying hours , tried google, etc... i've seen many programs, working, don't know why solution not. goal (for now) simple, want write cmd-line in case of mouse click or key press. first 1 works, second not. can tell why?

import java.awt.eventqueue;  import javax.swing.jframe; import java.awt.event.keyadapter; import java.awt.event.keyevent; import java.awt.event.mouseadapter; import java.awt.event.mouseevent;  public class test {      private jframe frame;      public static void main(string[] args) {         eventqueue.invokelater(new runnable() {             public void run() {                 try {                     test window = new test();                     window.frame.setvisible(true);                 } catch (exception e) {                     e.printstacktrace();                 }             }         });     }      public test() {         initialize();     }      private void initialize() {         frame = new jframe();         frame.getcontentpane().addmouselistener(new mouseadapter() {             @override             public void mouseclicked(mouseevent arg0) {                 system.out.println("mouse has clicked!");             }         });         frame.getcontentpane().addkeylistener(new keyadapter() {             @override             public void keypressed(keyevent arg0) {                 system.out.println("a key has pressed.");             }         });         frame.setbounds(100, 100, 450, 300);         frame.setdefaultcloseoperation(jframe.exit_on_close);     }  } 

well, had enough time trying find solution , i'm discovered it. not know why, not possible add keylistener jframe. add jbutton or jtextfield, etc... strange me, little bit :c