Here I give you a simple program to create Calculator using Java GUI. Please use this website as a reference link if you want to copy and paste this program.
If any question, don't be hesitate to leave a comment or contact my email.
package week09;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.border.LineBorder;
/**@author Novida Wayan Sari (1606954930)
* @version 20161127 07:35PM
* This class is Calculator class which is used to count a simple mathematics operation
* such as plus, minus, multiply and divide.
* This application is created to complete weekly task of Dasar-Dasar Pemrograman lecturing subject.
* This application uses JPanel as for the main component of GUI
* */
public class Calculator extends JPanel implements ActionListener {
private static final int WIDTH = 420; //constant of frame width
private static final int HEIGHT = 252; //constant of frame height
private JMenuBar menuBar; //Menu Bar (File, Help) <-- I do not have any idea to fill up the content
private JMenu fileMenu, helpMenu; //Referring Menu Bar, the content of menu bar
//mainPanel is a JPanel contains of main components except Menu Bar
//bottomPanel is a JPanel container of angkaPanel and operatorPanel
//angkaPanel is a JPanel container of all number button and "+" and "-" [Grid Layout]
//operatolPanel is a JPanel container of all operators button except "+" and "-" [Grid Layout]
private JPanel mainPanel, bottomPanel, angkaPanel, operatorPanel;
//-------------------------------------------------------------------------------------------------
private JButton[] btnAngka; //Array of number button {"0","1","2","3","4","5","6","7","8","9"}
private JButton[] btnControl; //Arrays of control button {"Backspace","C"}
private JButton[] btnOperator; //Array of operator button {"+","-","/","*","="}
private JTextField input; //Text field of input
private Color bckColor, mainColor, inputColor, textColor; //Colors used to make background, foreground color in this application
private float numb1 = 0; //variable which is used to save temporary value inputed by user
private String oldOperator = ""; //variable which is used to save temporary operator inputed by user
private boolean status = false; //the status to show if the operation is end
/*constructor
* */
public Calculator(){
this.bckColor = new Color(205,92,92); //Background Color
this.mainColor = new Color(128,0,0); //Button Color
this.inputColor = new Color(255,182,193); //Textfield background color
this.textColor = new Color(255,182,193); //Text of text field color
/*Main Panel uses Flow Layout which contains of Menu Bar and Main Panel*/
super.setLayout(new FlowLayout());
super.setPreferredSize(new Dimension(this.WIDTH, this.HEIGHT));
super.setBackground(bckColor);
super.setForeground(Color.WHITE);
/*----------------- Menu Bar ------------------------------------------------*/
this.menuBar = new JMenuBar();
this.menuBar.setPreferredSize(new Dimension(this.WIDTH-20, 30));
this.menuBar.setLocation(10, 0);
this.menuBar.setBackground(bckColor);
this.menuBar.setForeground(Color.white);
this.fileMenu = new JMenu("File");
this.helpMenu = new JMenu("Help");
this.menuBar.add(fileMenu);
this.menuBar.add(helpMenu);
/*----------------- End of Menu Bar -----------------------------------------*/
/*----------------- Input -----------------------------------------------------------------------------*/
this.input = new JTextField();
this.input.setPreferredSize(new Dimension(this.WIDTH-20, 30));
this.input.setBackground(inputColor);
this.input.setForeground(bckColor);
this.input.setHorizontalAlignment(JLabel.RIGHT);
this.input.setBorder(new LineBorder(bckColor));
this.input.setBorder(BorderFactory.createCompoundBorder(this.input.getBorder(), BorderFactory.createEmptyBorder(5, 5, 5, 5)));
this.input.setFont(new Font(this.input.getFont().getName(),Font.BOLD,this.input.getFont().getSize()));
this.input.setEditable(false);
this.input.setText("0");
/*---------------- End of Input-------------------------------------------------------------------------*/
/*---------------- Number Button -----------------------------------------------------------*/
this.btnAngka = new JButton[10];
this.btnControl = new JButton[2];
this.btnOperator = new JButton[6];
int colNum = 4;
for(int i=0;i<10;i++){
this.btnAngka[i] = new JButton(""+i);
this.btnAngka[i].setPreferredSize(new Dimension((this.WIDTH-20)/colNum,30));
this.btnAngka[i].setBackground(mainColor);
this.btnAngka[i].setForeground(textColor);
this.btnAngka[i].setBorder(new LineBorder(bckColor));
this.btnAngka[i].addActionListener(this);
}
/*--------------- End of Number Button ----------------------------------------------------*/
/*--------------- Control Button ----------------------------------------------------------*/
this.btnControl[0] = new JButton("Backspace");
this.btnControl[1] = new JButton("C");
for(int i=0;i<2;i++){
this.btnControl[i].setPreferredSize(new Dimension((this.WIDTH-20)/colNum,30));
this.btnControl[i].setBackground(mainColor);
this.btnControl[i].setForeground(textColor);
this.btnControl[i].setBorder(new LineBorder(bckColor));
this.btnControl[i].addActionListener(this);
}
/*--------------- End of Control Button ---------------------------------------------------*/
/*--------------- Operator Button ---------------------------------------------------------*/
this.btnOperator[0] = new JButton("+");
this.btnOperator[1] = new JButton("-");
this.btnOperator[2] = new JButton("/");
this.btnOperator[3] = new JButton("*");
this.btnOperator[4] = new JButton(".");
this.btnOperator[5] = new JButton("=");
for(int i=0;i<6;i++){
this.btnOperator[i].setPreferredSize(new Dimension((this.WIDTH-20)/colNum,30));
this.btnOperator[i].setBackground(mainColor);
this.btnOperator[i].setForeground(textColor);
this.btnOperator[i].setBorder(new LineBorder(bckColor));
this.btnOperator[i].addActionListener(this);
}
/*-------------- End of Operator Button --------------------------------------------------*/
//------------ BACKSPACE BUTTON -----------------------------------------------------------
this.btnControl[0].setPreferredSize(new Dimension((2*(this.WIDTH-20))/colNum,30));
this.btnControl[0].setLocation(10,70);
this.btnControl[0].setBackground(mainColor);
this.btnControl[0].setForeground(textColor);
this.btnControl[0].setBorder(new LineBorder(bckColor));
//------------ END OF BACKSPACE -----------------------------------------------------------
//------------ C BUTTON -----------------------------------------------------------
this.btnControl[1].setPreferredSize(new Dimension((this.WIDTH-20)/colNum,30));
this.btnControl[1].setBackground(mainColor);
this.btnControl[1].setForeground(textColor);
this.btnControl[1].setBorder(new LineBorder(bckColor));
//------------ END OF C BUTTON -----------------------------------------------------------
/*------------ Bottom Panel -------------------------------------------------------------*/
this.bottomPanel = new JPanel();
this.bottomPanel.setPreferredSize(new Dimension(this.WIDTH-20,120));
this.bottomPanel.setLayout(new BorderLayout());
/*------------ of Bottom Panel ----------------------------------------------------------*/
/*------------ Panel of number button -----------------------------------------------------*/
this.angkaPanel = new JPanel();
this.angkaPanel.setPreferredSize(new Dimension((3*(this.WIDTH-20))/4,120));
this.angkaPanel.setLayout(new GridLayout(4,3));
for(int i=0;i<3;i++){
for(int j=0;j<3;j++){
this.angkaPanel.add(this.btnAngka[(2-i)*3+1+j]);
}
}
this.angkaPanel.add(this.btnOperator[0]);
this.angkaPanel.add(this.btnAngka[0]);
this.angkaPanel.add(this.btnOperator[1]);
/*------------ End of Panel of number button ---------------------------------------------------*/
this.bottomPanel.add(this.angkaPanel, BorderLayout.WEST);
this.operatorPanel = new JPanel();
this.operatorPanel.setPreferredSize(new Dimension((this.WIDTH-20)/4,120));
this.operatorPanel.setLayout(new GridLayout(4,1));
for(int i=0;i<4;i++){
this.operatorPanel.add(this.btnOperator[i+2]);
}
this.bottomPanel.add(this.operatorPanel, BorderLayout.EAST);
/*------------ insert all components to main Panel and add it to this class ---------------------*/
this.mainPanel = new JPanel();
this.mainPanel.setLayout(new BorderLayout());
this.mainPanel.setBackground(bckColor);
/*---------------------- Main Panel uses Border Layout ------------*/
this.mainPanel.add(this.input, BorderLayout.NORTH);
this.mainPanel.add(this.btnControl[0], BorderLayout.WEST);
this.mainPanel.add(this.btnControl[1], BorderLayout.EAST);
this.mainPanel.add(this.bottomPanel, BorderLayout.SOUTH);
/*-----------------------------------------------------------------*/
super.add(menuBar);
super.add(mainPanel);
/*-----------------------------------------------------------------------------------------------*/
}
@Override
public void actionPerformed(ActionEvent evt) {
// TODO Auto-generated method stub
if(evt.getSource() instanceof JButton){
String btnText = ((JButton)evt.getSource()).getText();
String pattern = "[0-9]|[.]";
if(btnText == "Backspace"){
/*If the button pressed is backspace, then it will erase the last digit of shown inputed number*/
if(!this.input.getText().equals("")){
/*if there is digit in the last, then system should check if it is not zero (integer or decimal)*/
if(this.input.getText().equals("0.")){
this.input.setText("0");
}else{
/*if there is digit in the last, then system should check if previous digit is exist*/
if(this.input.getText().substring(0, this.input.getText().length()-1).equals("")){
this.input.setText("0");
}else{
this.input.setText(this.input.getText().substring(0, this.input.getText().length()-1));
}
}
}
this.status = false; //it shows that there is no temporary operation, backspace doesn't make any calculation process
}else if(btnText == "C"){
/*C will clear all shown number and change it into zero ------------------
* it also will clean up the history of number and operator inputed by the user
* */
this.input.setText("0");
this.numb1 = 0;
this.oldOperator = "";
this.status = false;
}else if(btnText.matches(pattern)){
if(btnText.equals(".") && this.input.getText().equals("0")){
/*If only zero shown in screen, and the user presses point to input decimal number -------------*/
this.input.setText("0.");
}else{
if(this.status == false){
if(this.input.getText().equals("0")){
/*If only zero show in screen, and the user presses any number, the zero in the first character shouldn't be shown*/
this.input.setText(btnText);
}else{
/*If the first number isn't zero, then the system only append pressed number*/
this.input.setText(this.input.getText()+btnText);
}
}else{
this.input.setText(btnText);
}
}
this.status = false;
}else{
try{
/*Every single time the user presses operator button, then the system should do calculation based on
*history of number and operator user pressed
**/
float result = this.count();
if(result == Math.floor(result)){
/*If the result of calculation can be figured out into integer form, then the system prioritize it first */
this.input.setText(""+(int)result);
}else{
this.input.setText(""+result);
}
this.status = true;
}catch(NumberFormatException e){
JOptionPane.showMessageDialog(null, "There was an error occured. Please restart the application and then try again!");
}
if(btnText.equals("=")){
/*= button will shows the result and erase the history of number and operator inputed by the user such C button does */
this.oldOperator = "";
this.numb1 = 0;
}else{
/*The system saves the operator as temporary operator to be executed in next operator pressed*/
this.oldOperator = btnText;
}
}
}
}
public float count(){
switch(this.oldOperator){
case "+":this.numb1=this.numb1+Float.valueOf((this.input.getText()));break;
case "-":this.numb1=this.numb1-Float.valueOf((this.input.getText()));break;
case "/":this.numb1=this.numb1/Float.valueOf((this.input.getText()));break;
case "*":this.numb1=this.numb1*Float.valueOf((this.input.getText()));break;
case "":this.numb1=Float.valueOf((this.input.getText()));break;
}
return this.numb1;
}
public static void main(String[] arg){
JFrame frame = new JFrame("Calculator");
frame.setSize(Calculator.WIDTH, Calculator.HEIGHT);
frame.setLocation(150, 150);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Calculator calc = new Calculator();
frame.add(calc);
frame.setVisible(true);
}
}
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