jf.addWindowListener(new WindowListener(){
@Override
public void windowActivated(WindowEvent e) {
}
@Override
public void windowClosed(WindowEvent e) {
}
@Override
public void windowClosing(WindowEvent e) {
Window window =e.getWindow();
window.dispose();
}
@Override
public void windowDeactivated(WindowEvent e) {
}
@Override
public void windowDeiconified(WindowEvent e) {
}
@Override
public void windowIconified(WindowEvent e) {
}
@Override
public void windowOpened(WindowEvent e) {
}});
jf是子窗体。加上这句就行了。