我正在尝试以编程方式单击JButton,使用doClick()方法很好。问题是,我想能够以编程方式单击当前处于焦点的任何按钮。
我可以使用.grabFocus()轻松地以编程方式为按钮提供焦点(至少看起来是这样),但由于某种原因.isFocusOwner()始终返回false。
如果运行代码,您可以直观地确认按钮“b2”确实处于焦点状态,但是if(frame.getFocusOwner() instanceof JButton)和if(b2.isFocusOwner)均返回false。
下面的代码说明了我遇到的问题。
我想象中我可能错过了一些明显的东西,但是任何建议都将非常棒。
public static void main(String[] args) {
JFrame frame = new JFrame();
JPanel panel = new JPanel();
JButton b1 = new JButton("b1");
JButton b2 = new JButton("b2");
JTextField j1 = new JTextField(10);
b1.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
System.out.println("Push the button...");
}
});
b2.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
System.out.println("...and let it go...");
}
});
panel.add(b1);
panel.add(b2);
panel.add(j1);
frame.add(panel);
frame.setSize(400, 400);
frame.setDefaultCloseOperation(frame.EXIT_ON_CLOSE);
frame.setVisible(true);
//// The two problems are below
// It looks like this does give 'b2' the focus, at least as far as the generated GUI is concerned
b2.grabFocus();
// First - Always returns false
if(frame.getFocusOwner() instanceof JButton) {
JButton focusedButton = (JButton) frame.getFocusOwner();
focusedButton.doClick();
System.out.println("In focus?");
}
else {
System.out.println("Apparently not");
}
// Second - Also always returns false
if(b2.isFocusOwner()) {
System.out.println("In focus...");
}
else {
System.out.println("Not in focus");
}
}