Memperbesar&Memperkecil Ukuran JFrame pake Button

Assalamu'alaikum wr.wb.

iseng2 gk ad kerjaan, akhirnya muncul ide buat bkin cranya  memperbesar dan memperkecil ukuran Jframe pke button, nah langsung aja codingnya ya:
class Size:
package ukuran;

import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;

/**
 *
 * @author tiwi
 */
public class Size implements ActionListener {

    JButton bbesar, bkecil;
    JFrame frame;
    int a = 200, b = 100;

    public Size() {
        frame = new JFrame("Ukuran");
        bbesar = new JButton("Besar");
        bkecil = new JButton("Kecil");
        Container c = frame.getContentPane();
        c.setLayout(new FlowLayout());
        c.add(bbesar);
        bbesar.addActionListener(this);
        c.add(bkecil);
        bkecil.addActionListener(this);
        frame.setVisible(true);
        frame.setDefaultCloseOperation(3);
        frame.setLocationRelativeTo(null);
        frame.setSize(a, b);
    }

    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == bbesar) {
            frame.setSize(a += 10, b += 10);
           
        }else if(e.getSource()==bkecil){
            frame.setSize(a -=10, b-=10);
        }
    }
}



method mainya: (jgn lupa pke lookandfell biar tampilanya keren,,,,)
package ukuran;

import com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

/**
 *
 * @author tiwi
 */
public class Main {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        try {
            // TODO code application logic here
            UIManager.setLookAndFeel(new NimbusLookAndFeel());
            new Size();
        } catch (UnsupportedLookAndFeelException ex) {
            Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

}
nah skrng screenshotnya:

ketika button besar d klik mka ukuran Jframenya jadi besar, sebaliknya klo di klik button yg kecil jdi kecil ukuran Jframenya,,,,,
oke simpel banget kan codingnya, selamat mencoba,,,,,


Wassalamu'alaikum Wr.Wb