create a Java application that implements a calculator, with design and features

Question

create a Java application that implements a calculator, with design and features which are similar to the standard calculator that comes with Windows (Accessoriescalculator). The calculator will have at least the following operations: addition, subtraction, multiplication, division, change sign, reciprocal (1/x), square root and clear. If you want you can add more operations like the trigonometrical operations (sine, cosine, and tangent) will be fine. Implementation of a decimal -> binary and binary -> decimal converter will be used for 10% extra credit. An example of a possible GUI is shown below

Explanation / Answer

import java.awt.*;

import java.awt.event.*;

// class CalcFrame for creating a calculator frame and added windolistener to

// close the calculator

class CalcFrame extends Frame {

CalcFrame( String str) {

// call to superclass

super(str);

// to close the calculator(Frame)

addWindowListener(new WindowAdapter() {

public void windowClosing (WindowEvent we) {

System.exit(0);

}

});

}

}

// main class Calculator implemnets two interfaces ActionListener

// and ItemListener

public class Calculator implements ActionListener, ItemListener {

// creating instances of objects

CalcFrame fr;

MenuBar mb;

Menu view, font, about;

MenuItem bold, regular, author;

CheckboxMenuItem basic, scientific;

CheckboxGroup cbg;

Checkbox radians, degrees;

TextField display;

Button key[] = new Button[20]; // creates a button object array of 20

Button clearAll, clearEntry, round;

Button scientificKey[] = new Button[10]; // creates a button array of 8

// declaring variables

boolean addButtonPressed, subtractButtonPressed, multiplyButtonPressed;

boolean divideButtonPressed, decimalPointPressed, powerButtonPressed;

boolean roundButtonPressed = false;

double initialNumber;// the first number for the two number operation

double currentNumber = 0; // the number shown in the screen while it is being pressed

int decimalPlaces = 0;

// main function

public static void main (String args[]) {

// constructor

Calculator calc = new Calculator();

calc.makeCalculator();

}

public void makeCalculator() {

// size of the button

final int BWIDTH = 25;

final int BHEIGHT = 25;

int count =1;

// create frame for the calculator

fr = new CalcFrame("Basic Calculator");

// set the size

fr.setSize(200,270);

fr.setBackground(Color.blue);;

// create a menubar for the frame

mb = new MenuBar();

// add menu the menubar

view = new Menu("View");

font = new Menu ("Font");

about = new Menu("About");

// create instance of object for View menu

basic = new CheckboxMenuItem("Basic",true);

// add a listener to receive item events when the state of an item changes

basic.addItemListener(this);

scientific = new CheckboxMenuItem("Scientific");

// add a listener to receive item events when the state of an item changes

scientific.addItemListener(this);

// create instance of object for font menu

bold = new MenuItem("Arial Bold");

bold.addActionListener(this);

regular = new MenuItem("Arial Regular");

regular.addActionListener(this);

// for about menu

author = new MenuItem("Author");

author.addActionListener(this);

// add the items in the menu

view.add(basic);

view.add(scientific);

font.add(bold);

font.add(regular);

about.add(author);

// add the menus in the menubar

mb.add(view);

mb.add(font);

mb.add(about);

// add menubar to the frame

fr.setMenuBar(mb);

// override the layout manager

fr.setLayout(null);

// set the initial numbers that is 1 to 9

for (int row = 0; row < 3; ++row) {

for (int col = 0; col < 3; ++col) {

// this will set the key from 1 to 9

key[count] = new Button(Integer.toString(count));

key[count].addActionListener(this);

// set the boundry for the keys

key[count].setBounds(30*(col + 1), 30*(row + 4),BWIDTH,BHEIGHT);

key[count].setBackground(Color.yellow);

// add to the frame

fr.add(key[count++]);

}

}

// Now create, addlistener and add to frame all other keys

//0

key[0] = new Button("0");

key[0].addActionListener(this);

key[0].setBounds(30,210,BWIDTH,BHEIGHT);

key[0].setBackground(Color.yellow);

fr.add(key[0]);

//decimal

key[10] = new Button(".");

key[10].addActionListener(this);

key[10].setBounds(60,210,BWIDTH,BHEIGHT);

key[10].setBackground(Color.yellow);

fr.add(key[10]);

//equals to

key[11] = new Button("=");

key[11].addActionListener(this);

key[11].setBounds(90,210,BWIDTH,BHEIGHT);

key[11].setBackground(Color.yellow);

fr.add(key[11]);

//multiply

key[12] = new Button("*");

key[12].addActionListener(this);

key[12].setBounds(120,120,BWIDTH,BHEIGHT);

key[12].setBackground(Color.yellow);

fr.add(key[12]);

//divide

key[13] = new Button("/");

key[13].addActionListener(this);

key[13].setBounds(120,150,BWIDTH,BHEIGHT);

key[13].setBackground(Color.yellow);

fr.add(key[13]);

//addition

key[14] = new Button("+");

key[14].addActionListener(this);

key[14].setBounds(120,180,BWIDTH,BHEIGHT);

key[14].setBackground(Color.yellow);

fr.add(key[14]);

//subtract

key[15] = new Button("-");

key[15].addActionListener(this);

key[15].setBounds(120,210,BWIDTH,BHEIGHT);

key[15].setBackground(Color.yellow);

fr.add(key[15]);

//reciprocal

key[16] = new Button("1/x");

key[16].addActionListener(this);

key[16].setBounds(150,120,BWIDTH,BHEIGHT);

key[16].setBackground(Color.yellow);

fr.add(key[16]);

//power

key[17] = new Button("x^n");

key[17].addActionListener(this);

key[17].setBounds(150,150,BWIDTH,BHEIGHT);

key[17].setBackground(Color.yellow);

fr.add(key[17]);

//change sign

key[18] = new Button("+/-");

key[18].addActionListener(this);

key[18].setBounds(150,180,BWIDTH,BHEIGHT);

key[18].setBackground(Color.yellow);

fr.add(key[18]);

//factorial

key[19] = new Button("x!");

key[19].addActionListener(this);

key[19].setBounds(150,210,BWIDTH,BHEIGHT);

key[19].setBackground(Color.yellow);

fr.add(key[19]);

// CA

clearAll = new Button("CA");

clearAll.addActionListener(this);

clearAll.setBounds(30, 240, BWIDTH+20, BHEIGHT);

clearAll.setBackground(Color.yellow);

fr.add(clearAll);

// CE

clearEntry = new Button("CE");

clearEntry.addActionListener(this);

clearEntry.setBounds(80, 240, BWIDTH+20, BHEIGHT);

clearEntry.setBackground(Color.yellow);

fr.add(clearEntry);

// round

round = new Button("Round");

round.addActionListener(this);

round.setBounds(130, 240, BWIDTH+20, BHEIGHT);

round.setBackground(Color.yellow);

fr.add(round);

// set display area

display = new TextField("0");

display.setBounds(30,90,150,20);

display.setBackground(Color.white);

// key for scientific calculator

// Sine

scientificKey[0] = new Button("Sin");

scientificKey[0].addActionListener(this);

scientificKey[0].setBounds(180, 120, BWIDTH + 10, BHEIGHT);

scientificKey[0].setVisible(false);

scientificKey[0].setBackground(Color.yellow);

fr.add(scientificKey[0]);

// cosine

scientificKey[1] = new Button("Cos");

scientificKey[1].addActionListener(this);

scientificKey[1].setBounds(180, 150, BWIDTH + 10, BHEIGHT);

scientificKey[1].setBackground(Color.yellow);

scientificKey[1].setVisible(false);

fr.add(scientificKey[1]);

// Tan

scientificKey[2] = new Button("Tan");

scientificKey[2].addActionListener(this);

scientificKey[2].setBounds(180, 180, BWIDTH + 10, BHEIGHT);

scientificKey[2].setBackground(Color.yellow);

scientificKey[2].setVisible(false);

fr.add(scientificKey[2]);

// PI

scientificKey[3] = new Button("Pi");

scientificKey[3].addActionListener(this);

scientificKey[3].setBounds(180, 210, BWIDTH + 10, BHEIGHT);

scientificKey[3].setBackground(Color.yellow);

scientificKey[3].setVisible(false);

fr.add(scientificKey[3]);

// aSine

scientificKey[4] = new Button("aSin");

scientificKey[4].addActionListener(this);

scientificKey[4].setBounds(220, 120, BWIDTH + 10, BHEIGHT);

scientificKey[4].setBackground(Color.yellow);

scientificKey[4].setVisible(false);

fr.add(scientificKey[4]);

// aCos

scientificKey[5] = new Button("aCos");

scientificKey[5].addActionListener(this);

scientificKey[5].setBounds(220, 150, BWIDTH + 10, BHEIGHT);

scientificKey[5].setBackground(Color.yellow);

scientificKey[5].setVisible(false);

fr.add(scientificKey[5]);

// aTan

scientificKey[6] = new Button("aTan");

scientificKey[6].addActionListener(this);

scientificKey[6].setBounds(220, 180, BWIDTH + 10, BHEIGHT);

scientificKey[6].setBackground(Color.yellow);

scientificKey[6].setVisible(false);

fr.add(scientificKey[6]);

// E

scientificKey[7] = new Button("E");

scientificKey[7].addActionListener(this);

scientificKey[7].setBounds(220, 210, BWIDTH + 10, BHEIGHT);

scientificKey[7].setBackground(Color.yellow);

scientificKey[7].setVisible(false);

fr.add(scientificKey[7]);

// to degrees

scientificKey[8] = new Button("todeg");

scientificKey[8].addActionListener(this);

scientificKey[8].setBounds(180, 240, BWIDTH + 10, BHEIGHT);

scientificKey[8].setBackground(Color.yellow);

scientificKey[8].setVisible(false);

fr.add(scientificKey[8]);

// to radians

scientificKey[9] = new Button("torad");

scientificKey[9].addActionListener(this);

scientificKey[9].setBounds(220, 240, BWIDTH + 10, BHEIGHT);

scientificKey[9].setBackground(Color.yellow);

scientificKey[9].setVisible(false);

fr.add(scientificKey[9]);

cbg = new CheckboxGroup();

degrees = new Checkbox("Degrees", cbg, true);

radians = new Checkbox("Radians", cbg, false);

degrees.addItemListener(this);

radians.addItemListener(this);

degrees.setBounds(185, 75, 3 * BWIDTH, BHEIGHT);

radians.setBounds(185, 95, 3 * BWIDTH, BHEIGHT);

degrees.setVisible(false);

radians.setVisible(false);

fr.add(degrees);

fr.add(radians);

fr.add(display);

fr.setVisible(true);

} // end of makeCalculator

public void actionPerformed(ActionEvent ae) {

String buttonText = ae.getActionCommand();

double displayNumber = Double.valueOf(display.getText()).doubleValue();

// if the button pressed text is 0 to 9

if((buttonText.charAt(0) >= '0') & (buttonText.charAt(0) <= '9')) {

if(decimalPointPressed) {

for (int i=1;i <=decimalPlaces; ++i)

currentNumber *= 10;

currentNumber +=(int)buttonText.charAt(0)- (int)'0';

for (int i=1;i <=decimalPlaces; ++i) {

currentNumber /=10;

}

++decimalPlaces;

display.setText(Double.toString(currentNumber));

}

else if (roundButtonPressed) {

int decPlaces = (int)buttonText.charAt(0) - (int)'0';

for (int i=0; i< decPlaces; ++i)

displayNumber *=10;

displayNumber = Math.round(displayNumber);

for (int i = 0; i < decPlaces; ++i) {

displayNumber /=10;

}

display.setText(Double.toString(displayNumber));

roundButtonPressed = false;

}

else {

currentNumber = currentNumber * 10 + (int)buttonText.charAt(0)-(int)'0';

display.setText(Integer.toString((int)currentNumber));

}

}

// if button pressed is addition

if(buttonText == "+") {

addButtonPressed = true;

initialNumber = displayNumber;

currentNumber = 0;

decimalPointPressed = false;

}

// if button pressed is subtract

if (buttonText == "-") {

subtractButtonPressed = true;

initialNumber = displayNumber;

currentNumber = 0;

decimalPointPressed = false;

}

// if button pressed is divide

if (buttonText == "/") {

divideButtonPressed = true;

initialNumber = displayNumber;

currentNumber = 0;

decimalPointPressed = false;

}

// if button pressed is multiply

if (buttonText == "*") {

multiplyButtonPressed = true;

initialNumber = displayNumber;

currentNumber = 0;

decimalPointPressed = false;

}

// if button pressed is reciprocal

if (buttonText == "1/x") {

// call reciprocal method

display.setText(reciprocal(displayNumber));

currentNumber = 0;

decimalPointPressed = false;

}

// if button is pressed to change a sign

if (buttonText == "+/-") {

// call changesign meyhod to change the sign

display.setText(changeSign(displayNumber));

currentNumber = 0;

decimalPointPressed = false;

}

// factorial button

if (buttonText == "x!") {

display.setText(factorial(displayNumber));

currentNumber = 0;

decimalPointPressed = false;

}

// power button

if (buttonText == "x^n") {

powerButtonPressed = true;

initialNumber = displayNumber;

currentNumber = 0;

decimalPointPressed = false;

}

// now for scientific buttons

if (buttonText == "Sin") {

if (degrees.getState())

display.setText(Double.toString(Math.sin(Math.PI * displayNumber/180)));

else {

display.setText(Double.toString(Math.sin(displayNumber)));

currentNumber = 0;

decimalPointPressed = false;

}

}

if (buttonText == "Cos") {

if (degrees.getState())

display.setText(Double.toString(Math.cos(Math.PI * displayNumber/180)));

else{

display.setText(Double.toString(Math.cos(displayNumber)));

currentNumber = 0;

decimalPointPressed = false;

}

}

if (buttonText == "Tan") {

if (degrees.getState())

display.setText(Double.toString(Math.tan(Math.PI * displayNumber/180)));

else {

display.setText(Double.toString(Math.tan(displayNumber)));

currentNumber = 0;

decimalPointPressed = false;

}

}

if (buttonText == "aSin") {

if (degrees.getState())

display.setText(Double.toString(Math.asin(displayNumber)* 180/Math.PI ));

else {

display.setText(Double.toString(Math.asin(displayNumber)));

currentNumber = 0;

decimalPointPressed = false;

}

}

if (buttonText == "aCos") {

if (degrees.getState())

display.setText(Double.toString(Math.acos(displayNumber)* 180/Math.PI ));

else {

display.setText(Double.toString(Math.acos(displayNumber)));

currentNumber = 0;

decimalPointPressed = false;

}

}

if (buttonText == "aTan") {

if (degrees.getState())

display.setText(Double.toString(Math.atan(displayNumber)* 180/Math.PI ));

else {

display.setText(Double.toString(Math.atan(displayNumber)));

currentNumber = 0;

decimalPointPressed = false;

}

}

// this will convert the numbers displayed to degrees

if (buttonText == "todeg")

display.setText(Double.toString(Math.toDegrees(displayNumber)));

// this will convert the numbers displayed to radians

if (buttonText == "torad")

display.setText(Double.toString(Math.toRadians(displayNumber)));

if (buttonText == "Pi") {

display.setText(Double.toString(Math.PI));

currentNumber =0;

decimalPointPressed = false;

}

if (buttonText == "Round")

roundButtonPressed = true;

// check if decimal point is pressed

if (buttonText == ".") {

String displayedNumber = display.getText();

boolean decimalPointFound = false;

int i;

decimalPointPressed = true;

// check for decimal point

for (i =0; i < displayedNumber.length(); ++i) {

if(displayedNumber.charAt(i) == '.') {

decimalPointFound = true;

continue;

}

}

if (!decimalPointFound)

decimalPlaces = 1;

}

if(buttonText == "CA"){

// set all buttons to false

resetAllButtons();

display.setText("0");

currentNumber = 0;

}

if (buttonText == "CE") {

display.setText("0");

currentNumber = 0;

decimalPointPressed = false;

}

if (buttonText == "E") {

display.setText(Double.toString(Math.E));

currentNumber = 0;

decimalPointPressed = false;

}

// the main action

if (buttonText == "=") {

currentNumber = 0;

// if add button is pressed

if(addButtonPressed)

display.setText(Double.toString(initialNumber + displayNumber));

// if subtract button is pressed

if(subtractButtonPressed)

display.setText(Double.toString(initialNumber - displayNumber));

// if divide button is pressed

if (divideButtonPressed) {

// check if the divisor is zero

if(displayNumber == 0) {

MessageBox mb = new MessageBox ( fr, "Error ", true, "Cannot divide by zero.");

mb.show();

}

else

display.setText(Double.toString(initialNumber/displayNumber));

}

// if multiply button is pressed

if(multiplyButtonPressed)

display.setText(Double.toString(initialNumber * displayNumber));

// if power button is pressed

if (powerButtonPressed)

display.setText(power(initialNumber, displayNumber));

// set all the buttons to false

resetAllButtons();

}

if (buttonText == "Arial Regular") {

for (int i =0; i < 10; ++i)

key[i].setFont(new Font("Arial", Font.PLAIN, 12));

}

if (buttonText == "Arial Bold") {

for (int i =0; i < 10; ++i)

key[i].setFont(new Font("Arial", Font.BOLD, 12));

}

if (buttonText == "Author") {

MessageBox mb = new MessageBox ( fr, "Calculator ver 1.0 beta ", true, "Author: Inder Mohan Singh.");

mb.show();

}

} // end of action events

public void itemStateChanged(ItemEvent ie) {

if (ie.getItem() == "Basic") {

basic.setState(true);

scientific.setState(false);

fr.setTitle("Basic Calculator");

fr.setSize(200,270);

// check if the scientific keys are visible. if true hide them

if (scientificKey[0].isVisible()) {

for (int i=0; i < 8; ++i)

scientificKey[i].setVisible(false);

radians.setVisible(false);

degrees.setVisible(false);

}

}

if (ie.getItem() == "Scientific") {

basic.setState(false);

scientific.setState(true);

fr.setTitle("Scientific Calculator");

fr.setSize(270,270);

// check if the scientific keys are visible. if true display them

if (!scientificKey[0].isVisible()) {

for (int i=0; i < 10; ++i)

scientificKey[i].setVisible(true);

radians.setVisible(true);

degrees.setVisible(true);

}

}

} // end of itemState

// this method will reset all the buttonPressed property to false

public void resetAllButtons() {

addButtonPressed = false;

subtractButtonPressed = false;

multiplyButtonPressed = false;

divideButtonPressed = false;

decimalPointPressed = false;

powerButtonPressed = false;

roundButtonPressed = false;

}

public String factorial(double num) {

int theNum = (int)num;

if (theNum < 1) {

MessageBox mb = new MessageBox (fr, "Facorial Error", true,

"Cannot find the factorial of numbers less than 1.");

mb.show();

return ("0");

}

else {

for (int i=(theNum -1); i > 1; --i)

theNum *= i;

return Integer.toString(theNum);

}

}

public String reciprocal(double num) {

if (num ==0) {

MessageBox mb = new MessageBox(fr,"Reciprocal Error", true,

"Cannot find the reciprocal of 0");

mb.show();

}

else

num = 1/num;

return Double.toString(num);

}

public String power (double base, double index) {

return Double.toString(Math.pow(base, index));

}

public String changeSign(double num) {

return Double.toString(-num);

}

}

class MessageBox extends Dialog implements ActionListener {

Button ok;

MessageBox(Frame f, String title, boolean mode, String message) {

super(f, title, mode);

Panel centrePanel = new Panel();

Label lbl = new Label(message);

centrePanel.add(lbl);

add(centrePanel, "Center");

Panel southPanel = new Panel();

ok = new Button ("OK");

ok.addActionListener(this);

southPanel.add(ok);

add(southPanel, "South");

pack();

addWindowListener (new WindowAdapter() {

public void windowClosing (WindowEvent we) {

System.exit(0);

}

});

}

public void actionPerformed(ActionEvent ae) {

dispose();

}

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