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import java.awt.Component;
import java.awt.FlowLayout;
import java.awt.Window;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JButton;
import javax.swing.JFrame;
public class Main {
public static void main(String[] argv) throws Exception {
JFrame frame = new JFrame();
JButton component1 = new JButton("1");
JButton component2 = new JButton("2");
JButton component3 = new JButton("3");
frame.setLayout(new FlowLayout());
frame.add(component1);
frame.add(component2);
frame.add(component3);
InitialFocusSetter.setInitialFocus(frame, component2);
frame.pack();
frame.setVisible(true);
}
}
class InitialFocusSetter {
public static void setInitialFocus(Window w, Component c) {
w.addWindowListener(new FocusSetter(c));
}
}
class FocusSetter extends WindowAdapter {
Component initComp;
FocusSetter(Component c) {
initComp = c;
}
public void windowOpened(WindowEvent e) {
initComp.requestFocus();
e.getWindow().removeWindowListener(this);
}
}
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