"f.setPreferredSize(new Dimension(300, 200));"[code]




     [code]:
  import java.awt.*;
import javax.swing.*;
public class ATM
{
    private JFrame f;
    private JTextField vn;
    private JTextArea v;
    private JPanel p;
    private JPanel pp;
    private JPanel ppp;
    private JPanel pppp;
    private JButton one, two, three;
    private JButton q, w, e, r, t, y, u, i, o, n, a, s;
    

    public ATM()
    {
        f = new JFrame("ATM Program");
        p = new JPanel();
        pp = new JPanel();
        ppp = new JPanel();
        pppp = new JPanel();
        vn = new JTextField();
        v = new JTextArea();
        one = new JButton("Display Account Balance");
        two = new JButton("Make a Deposit");
        three = new JButton("Make a Withdraw");
        q = new JButton("1");
        w = new JButton("2");
        e = new JButton("3");
        r = new JButton("4");
        t = new JButton("5");
        y = new JButton("6");
        u = new JButton("7");
        i = new JButton("8");
        o = new JButton("9");
        n = new JButton("0");
        s = new JButton(".");
        a = new JButton("Enter");
    }
    
    public void ATM()
    {
        f.setPreferredSize(new Dimension(300, 200));
        pp.setLayout(new GridLayout(4,1));
        pp.add(one);
        pp.add(two);
        pp.add(three);
        pp.add(vn);
        p.add(pp, BorderLayout.NORTH);
        pppp.setLayout(new GridLayout(1, 0));
        pppp.add(v = new JTextArea(20, 20));
        p.add(pppp, BorderLayout.CENTER);
        ppp.setLayout(new GridLayout(4,3));
        ppp.add(q);
        ppp.add(w);
        ppp.add(e);
        ppp.add(r);
        ppp.add(t);
        ppp.add(y);
        ppp.add(u);
        ppp.add(i);
        ppp.add(o);
        ppp.add(n);
        ppp.add(a);
        ppp.add(s);
        p.add(ppp, BorderLayout.SOUTH);
        f.add(p);    
        f.pack();
        f.setVisible(true);
    }

    public static void main(String args[])
    {
        ATM guiWindow = new ATM();
        guiWindow.ATM();
    }
}