import java.awt.Font;

import java.awt.GridBagConstraints;

import java.awt.GridBagLayout;

import java.awt.GridLayout;

import java.awt.Insets;

import javax.swing.*;

public class JavaLesson29 extends JFrame{

JButton but1, but2, but3, but4, but5, but6,

but7, but8, but9, but0, butPlus, butMinus,

clearAll;

JTextField textResult;

int num1, num2;

public static void main(String[] args){

new JavaLesson29();

}

public JavaLesson29(){

// Create the frame, position it and handle closing it

this.setSize(400,400);

this.setLocationRelativeTo(null);

this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

this.setTitle("Calculator");

JPanel thePanel = new JPanel();

// Create a Grid Layout with as many rows as needed

// and 3 columns. The last 2 parameters create a

// horizontal gap of 2 pixels and a vertical gap of

// 2 pixels.

// thePanel.setLayout(new GridLayout(0,3,2,2));

thePanel.setLayout(new GridBagLayout());

// You create a GridBagContraints object that defines

// defaults for your components

GridBagConstraints gridConstraints = new GridBagConstraints();

// Define the x position of the component

gridConstraints.gridx = 1;

// Define the y position of the component

gridConstraints.gridy = 1;

// Number of columns the component takes up

gridConstraints.gridwidth = 1;

// Number of rows the component takes up

gridConstraints.gridheight = 1;

// Gives the layout manager a hint on how to adjust

// component width (0 equals fixed)

gridConstraints.weightx = 50;

// Gives the layout manager a hint on how to adjust

// component height (0 equals fixed)

gridConstraints.weighty = 100;

// Defines padding top, left, bottom, right

gridConstraints.insets = new Insets(5,5,5,5);

// Defines where to place components if they don't

// fill the space: CENTER, NORTH, SOUTH, EAST, WEST

// NORTHEAST, etc.

gridConstraints.anchor = GridBagConstraints.CENTER;

// How should the component be stretched to fill the

// space: NONE, HORIZONTAL, VERTICAL, BOTH

gridConstraints.fill = GridBagConstraints.BOTH;

textResult = new JTextField("0",20);

// Defines the font to use in the text field

Font font = new Font("Helvetica", Font.PLAIN, 18);

textResult.setFont(font);

but1 = new JButton("1");

but2 = new JButton("2");

but3 = new JButton("3");

but4 = new JButton("4");

but5 = new JButton("5");

but6 = new JButton("6");

but7 = new JButton("7");

but8 = new JButton("8");

but9 = new JButton("9");

butPlus = new JButton("+");

but0 = new JButton("0");

butMinus = new JButton("-");

clearAll = new JButton("C");

thePanel.add(clearAll,gridConstraints);

gridConstraints.gridwidth = 20;

gridConstraints.gridx = 5;

thePanel.add(textResult,gridConstraints);

gridConstraints.gridwidth = 1;

gridConstraints.gridx = 1;

gridConstraints.gridy = 2;

thePanel.add(but1,gridConstraints);

gridConstraints.gridx = 5;

thePanel.add(but2,gridConstraints);

gridConstraints.gridx = 9;

thePanel.add(but3,gridConstraints);

gridConstraints.gridx = 1;

gridConstraints.gridy = 3;

thePanel.add(but4,gridConstraints);

gridConstraints.gridx = 5;

thePanel.add(but5,gridConstraints);

gridConstraints.gridx = 9;

thePanel.add(but6,gridConstraints);

gridConstraints.gridx = 1;

gridConstraints.gridy = 4;

thePanel.add(but7,gridConstraints);

gridConstraints.gridx = 5;

thePanel.add(but8,gridConstraints);

gridConstraints.gridx = 9;

thePanel.add(but9,gridConstraints);

gridConstraints.gridx = 1;

gridConstraints.gridy = 5;

thePanel.add(butPlus,gridConstraints);

gridConstraints.gridx = 5;

thePanel.add(but0,gridConstraints);

gridConstraints.gridx = 9;

thePanel.add(butMinus,gridConstraints);

// Adding buttons using the Grid Layout

/*

thePanel.add(but1);

thePanel.add(but2);

thePanel.add(but3);

thePanel.add(but4);

thePanel.add(but5);

thePanel.add(but6);

thePanel.add(but7);

thePanel.add(but8);

thePanel.add(but9);

thePanel.add(butPlus);

thePanel.add(but0);

thePanel.add(butMinus);

*/

this.add(thePanel);

this.setVisible(true);

} // END OF JavaLesson29 CONSTRUCTOR

} // END OF JavaLesson29 CLASS