Non lo fa in automatico? Prova questo.
codice:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JToolBar;
public class NewClass extends JFrame{
JFrame f;
public NewClass() {
Container content = this.getContentPane();
//Faccio una toolbar
JToolBar toolBar = new JToolBar("");
toolBar.add(new JButton("a"));
toolBar.add(new JButton("b"));
content.add(toolBar, BorderLayout.NORTH);
//Faccio un pannello con bottone per l'evento ridimensionamento
JPanel pane = new JPanel();
pane.setBackground(Color.RED);
JButton b = new JButton("Resize!");
f = this;
b.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
f.setSize(1000, 1000);
}
});
pane.add(b);
content.add(pane,BorderLayout.CENTER);
//Visualizzo la finestra
this.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
this.setSize(100, 100);
this.setVisible(true);
}
public static void main(String[] args) {
new NewClass();
}
}