Java AWT GridLayout create calculator layout

import java.awt.BorderLayout;
import java.awt.GridLayout;
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.JTextField;

public class Main {

  public static void main(String[] args) {

    JTextField textField = new JTextField();
    textField.setColumns(25);//w w w .  java  2  s  . c  o  m

    JPanel panel = new JPanel();
 
    panel.setLayout(new GridLayout(4, 4, 0, 0));

    JButton button = new JButton("7");
    panel.add(button);

    JButton button_2 = new JButton("8");
    panel.add(button_2);

    JButton button_1 = new JButton("9");
    button_1.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent arg0) {
      }
    });
    panel.add(button_1);

    JButton button_3 = new JButton("/");
    panel.add(button_3);

    JButton button_4 = new JButton("4");
    panel.add(button_4);

    JButton button_5 = new JButton("5");
    panel.add(button_5);

    JButton button_6 = new JButton("6");
    panel.add(button_6);

    JButton button_7 = new JButton("*");
    panel.add(button_7);

    JButton button_8 = new JButton("1");
    panel.add(button_8);

    JButton button_9 = new JButton("2");
    panel.add(button_9);

    JButton button_10 = new JButton("3");
    panel.add(button_10);

    JButton button_11 = new JButton("-");
    panel.add(button_11);

    JButton button_12 = new JButton("0");
    panel.add(button_12);

    JButton button_13 = new JButton(".");
    panel.add(button_13);

    JButton button_14 = new JButton("=");
    panel.add(button_14);

    JButton button_15 = new JButton("+");
    panel.add(button_15);
    
    JFrame frmCalculator = new JFrame();
    frmCalculator.setTitle("Calculator");
    frmCalculator.setBounds(100, 100, 217, 258);
    frmCalculator.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frmCalculator.getContentPane().setLayout(new BorderLayout(0, 0));
    frmCalculator.getContentPane().add(panel, BorderLayout.CENTER);
    frmCalculator.getContentPane().add(textField, BorderLayout.NORTH);

    frmCalculator.setVisible(true);
  }

}