please, something went xxx*x, and that’s not true at all, check that
JButton Size - java.awt.Dimension[width=400,height=40]
JPanel Size - java.awt.Dimension[width=640,height=480]
JFrame Size - java.awt.Dimension[width=646,height=505]
code (basic stuff from Trail: Creating a GUI With JFC/Swing , and yet I still satisfied that that would be outdated )
EDIT: forget setDefaultCloseOperation()
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class FrameSize {
private JFrame frm = new JFrame();
private JPanel pnl = new JPanel();
private JButton btn = new JButton("Get ScreenSize for JComponents");
public FrameSize() {
btn.setPreferredSize(new Dimension(400, 40));
btn.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
System.out.println("JButton Size - " + btn.getSize());
System.out.println("JPanel Size - " + pnl.getSize());
System.out.println("JFrame Size - " + frm.getSize());
}
});
pnl.setPreferredSize(new Dimension(640, 480));
pnl.add(btn, BorderLayout.SOUTH);
frm.add(pnl, BorderLayout.CENTER);
frm.setLocation(150, 100);
frm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // EDIT
frm.setResizable(false);
frm.pack();
frm.setVisible(true);
}