When you are a computer science engineer student or a programmer in a software company. Sometimes you need to build apps or programs with java for class assignments or client work. Calculator programs in Java is a common program for Java projects.
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So, let’s see how can we build Calculator programs in Java with Java Calculator Code.
Calculator in Java with Source Code
/*********************************************
Save this file as MyCalculator.java
to compile it use
javac MyCalculator.java
to use the calcuator do this
java MyCalculator**********************************************/
import java.awt.*;
import java.awt.event.*;
/*********************************************/
public class MyCalculator extends Frame
{
public boolean setClear=true;
double number, memValue;
char op;
String digitButtonText[] = {“7”, “8”, “9”, “4”, “5”, “6”, “1”, “2”, “3”, “0”, “+/-“, “.” };
String operatorButtonText[] = {“/”, “sqrt”, “*”, “%”, “-“, “1/X”, “+”, “=” };
String memoryButtonText[] = {“MC”, “MR”, “MS”, “M+” };
String specialButtonText[] = {“Backspc”, “C”, “CE” };
MyDigitButton digitButton[]=new MyDigitButton[digitButtonText.length];
MyOperatorButton operatorButton[]=new MyOperatorButton[operatorButtonText.length];
MyMemoryButton memoryButton[]=new MyMemoryButton[memoryButtonText.length];
MySpecialButton specialButton[]=new MySpecialButton[specialButtonText.length];
Label displayLabel=new Label(“0”,Label.RIGHT);
Label memLabel=new Label(” “,Label.RIGHT);
final int FRAME_WIDTH=325,FRAME_HEIGHT=325;
final int HEIGHT=30, WIDTH=30, H_SPACE=10,V_SPACE=10;
final int TOPX=30, TOPY=50;
///////////////////////////
MyCalculator(String frameText)//constructor
{
super(frameText);
int tempX=TOPX, y=TOPY;
displayLabel.setBounds(tempX,y,240,HEIGHT);
displayLabel.setBackground(Color.BLUE);
displayLabel.setForeground(Color.WHITE);
add(displayLabel);
memLabel.setBounds(TOPX, TOPY+HEIGHT+ V_SPACE,WIDTH, HEIGHT);
add(memLabel);
// set Co-ordinates for Memory Buttons
tempX=TOPX;
y=TOPY+2*(HEIGHT+V_SPACE);
for(int i=0; i<memoryButton.length; i++)
{
memoryButton[i]=new MyMemoryButton(tempX,y,WIDTH,HEIGHT,memoryButtonText[i], this);
memoryButton[i].setForeground(Color.RED);
y+=HEIGHT+V_SPACE;
}
//set Co-ordinates for Special Buttons
tempX=TOPX+1*(WIDTH+H_SPACE); y=TOPY+1*(HEIGHT+V_SPACE);
for(int i=0;i<specialButton.length;i++)
{
specialButton[i]=new MySpecialButton(tempX,y,WIDTH*2,HEIGHT,specialButtonText[i], this);
specialButton[i].setForeground(Color.RED);
tempX=tempX+2*WIDTH+H_SPACE;
}
//set Co-ordinates for Digit Buttons
int digitX=TOPX+WIDTH+H_SPACE;
int digitY=TOPY+2*(HEIGHT+V_SPACE);
tempX=digitX; y=digitY;
for(int i=0;i<digitButton.length;i++)
{
digitButton[i]=new MyDigitButton(tempX,y,WIDTH,HEIGHT,digitButtonText[i], this);
digitButton[i].setForeground(Color.BLUE);
tempX+=WIDTH+H_SPACE;
if((i+1)%3==0){tempX=digitX; y+=HEIGHT+V_SPACE;}
}
//set Co-ordinates for Operator Buttons
int opsX=digitX+2*(WIDTH+H_SPACE)+H_SPACE;
int opsY=digitY;
tempX=opsX; y=opsY;
for(int i=0;i<operatorButton.length;i++)
{
tempX+=WIDTH+H_SPACE;
operatorButton[i]=new MyOperatorButton(tempX,y,WIDTH,HEIGHT,operatorButtonText[i], this);
operatorButton[i].setForeground(Color.RED);
if((i+1)%2==0){tempX=opsX; y+=HEIGHT+V_SPACE;}
}
addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent ev)
{System.exit(0);}
});
setLayout(null);
setSize(FRAME_WIDTH,FRAME_HEIGHT);
setVisible(true);
}
//////////////////////////////////
static String getFormattedText(double temp)
{
String resText=””+temp;
if(resText.lastIndexOf(“.0”)>0)
resText=resText.substring(0,resText.length()-2);
return resText;
}
////////////////////////////////////////
public static void main(String []args)
{
new MyCalculator(“Calculator – JavaTpoint”);
}
}
/*******************************************/
class MyDigitButton extends Button implements ActionListener
{
MyCalculator cl;
//////////////////////////////////////////
MyDigitButton(int x,int y, int width,int height,String cap, MyCalculator clc)
{
super(cap);
setBounds(x,y,width,height);
this.cl=clc;
this.cl.add(this);
addActionListener(this);
}
////////////////////////////////////////////////
static boolean isInString(String s, char ch)
{
for(int i=0; i<s.length();i++) if(s.charAt(i)==ch) return true;
return false;
}
/////////////////////////////////////////////////
public void actionPerformed(ActionEvent ev)
{
String tempText=((MyDigitButton)ev.getSource()).getLabel();
if(tempText.equals(“.”))
{
if(cl.setClear)
{cl.displayLabel.setText(“0.”);cl.setClear=false;}
else if(!isInString(cl.displayLabel.getText(),’.’))
cl.displayLabel.setText(cl.displayLabel.getText()+”.”);
return;
}
int index=0;
try{
index=Integer.parseInt(tempText);
}catch(NumberFormatException e){return;}
if (index==0 && cl.displayLabel.getText().equals(“0”)) return;
if(cl.setClear)
{cl.displayLabel.setText(“”+index);cl.setClear=false;}
else
cl.displayLabel.setText(cl.displayLabel.getText()+index);
}//actionPerformed
}//class defination
/********************************************/
class MyOperatorButton extends Button implements ActionListener
{
MyCalculator cl;
MyOperatorButton(int x,int y, int width,int height,String cap, MyCalculator clc)
{
super(cap);
setBounds(x,y,width,height);
this.cl=clc;
this.cl.add(this);
addActionListener(this);
}
///////////////////////
public void actionPerformed(ActionEvent ev)
{
String opText=((MyOperatorButton)ev.getSource()).getLabel();
cl.setClear=true;
double temp=Double.parseDouble(cl.displayLabel.getText());
if(opText.equals(“1/x”))
{
try
{double tempd=1/(double)temp;
cl.displayLabel.setText(MyCalculator.getFormattedText(tempd));}
catch(ArithmeticException excp)
{cl.displayLabel.setText(“Divide by 0.”);}
return;
}
if(opText.equals(“sqrt”))
{
try
{double tempd=Math.sqrt(temp);
cl.displayLabel.setText(MyCalculator.getFormattedText(tempd));}
catch(ArithmeticException excp)
{cl.displayLabel.setText(“Divide by 0.”);}
return;
}
if(!opText.equals(“=”))
{
cl.number=temp;
cl.op=opText.charAt(0);
return;
}
// process = button pressed
switch(cl.op)
{
case ‘+’:
temp+=cl.number;break;
case ‘-‘:
temp=cl.number-temp;break;
case ‘*’:
temp*=cl.number;break;
case ‘%’:
try{temp=cl.number%temp;}
catch(ArithmeticException excp)
{cl.displayLabel.setText(“Divide by 0.”); return;}
break;
case ‘/’:
try{temp=cl.number/temp;}
catch(ArithmeticException excp)
{cl.displayLabel.setText(“Divide by 0.”); return;}
break;
}//switch
cl.displayLabel.setText(MyCalculator.getFormattedText(temp));
//cl.number=temp;
}//actionPerformed
}//class
/****************************************/
class MyMemoryButton extends Button implements ActionListener
{
MyCalculator cl;
/////////////////////////////////
MyMemoryButton(int x,int y, int width,int height,String cap, MyCalculator clc)
{
super(cap);
setBounds(x,y,width,height);
this.cl=clc;
this.cl.add(this);
addActionListener(this);
}
////////////////////////////////////////////////
public void actionPerformed(ActionEvent ev)
{
char memop=((MyMemoryButton)ev.getSource()).getLabel().charAt(1);
cl.setClear=true;
double temp=Double.parseDouble(cl.displayLabel.getText());
switch(memop)
{
case ‘C’:
cl.memLabel.setText(” “);cl.memValue=0.0;break;
case ‘R’:
cl.displayLabel.setText(MyCalculator.getFormattedText(cl.memValue));break;
case ‘S’:
cl.memValue=0.0;
case ‘+’:
cl.memValue+=Double.parseDouble(cl.displayLabel.getText());
if(cl.displayLabel.getText().equals(“0”) || cl.displayLabel.getText().equals(“0.0”) )
cl.memLabel.setText(” “);
else
cl.memLabel.setText(“M”);
break;
}//switch
}//actionPerformed
}//class
/*****************************************/
class MySpecialButton extends Button implements ActionListener
{
MyCalculator cl;
MySpecialButton(int x,int y, int width,int height,String cap, MyCalculator clc)
{
super(cap);
setBounds(x,y,width,height);
this.cl=clc;
this.cl.add(this);
addActionListener(this);
}
//////////////////////
static String backSpace(String s)
{
String Res=””;
for(int i=0; i<s.length()-1; i++) Res+=s.charAt(i);
return Res;
}
//////////////////////////////////////////////////////////
public void actionPerformed(ActionEvent ev)
{
String opText=((MySpecialButton)ev.getSource()).getLabel();
//check for backspace button
if(opText.equals(“Backspc”))
{
String tempText=backSpace(cl.displayLabel.getText());
if(tempText.equals(“”))
cl.displayLabel.setText(“0”);
else
cl.displayLabel.setText(tempText);
return;
}
//check for “C” button i.e. Reset
if(opText.equals(“C”))
{
cl.number=0.0; cl.op=’ ‘; cl.memValue=0.0;
cl.memLabel.setText(” “);
}
//it must be CE button pressed
cl.displayLabel.setText(“0”);cl.setClear=true;
}//actionPerformed
}//class
/*********************************************
Features not implemented and few bugsi) No coding done for “+/-” button.
ii) Menubar is not included.
iii)Not for Scientific calculation
iv)Some of the computation may lead to unexpected result
due to the representation of Floating point numbers in computer
is an approximation to the given value that can be stored
physically in memory.
***********************************************/
Another Source Code For Java Calculator
//Imports are listed in full to show what’s being used
//could just import javax.swing.* and java.awt.* etc..
import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.BorderLayout;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.JButton;
import java.awt.Container;
public class SimpleCalc implements ActionListener{JFrame guiFrame;
JPanel buttonPanel;
JTextField numberCalc;
int calcOperation = 0;
int currentCalc;
//Note: Typically the main method will be in a
//separate class. As this is a simple one class
//example it’s all in the one class.
public static void main(String[] args) {
//Use the event dispatch thread for Swing components
EventQueue.invokeLater(new Runnable()
{
@Override
public void run()
{
new SimpleCalc();
}
});
}
public SimpleCalc()
{
guiFrame = new JFrame();
//make sure the program exits when the frame closes
guiFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
guiFrame.setTitle(“Simple Calculator”);
guiFrame.setSize(300,300);
//This will center the JFrame in the middle of the screen
guiFrame.setLocationRelativeTo(null);
numberCalc = new JTextField();
numberCalc.setHorizontalAlignment(JTextField.RIGHT);
numberCalc.setEditable(false);
guiFrame.add(numberCalc, BorderLayout.NORTH);
buttonPanel = new JPanel();
//Make a Grid that has three rows and four columns
buttonPanel.setLayout(new GridLayout(4,3));
guiFrame.add(buttonPanel, BorderLayout.CENTER);
//Add the number buttons
for (int i=1;i<10;i++)
{
addButton(buttonPanel, String.valueOf(i));
}
JButton addButton = new JButton(“+”);
addButton.setActionCommand(“+”);
OperatorAction subAction = new OperatorAction(1);
addButton.addActionListener(subAction);
JButton subButton = new JButton(“-“);
subButton.setActionCommand(“-“);
OperatorAction addAction = new OperatorAction(2);
subButton.addActionListener(addAction);
JButton equalsButton = new JButton(“=”);
equalsButton.setActionCommand(“=”);
equalsButton.addActionListener(new ActionListener()
{
@Override
public void actionPerformed(ActionEvent event)
{
if (!numberCalc.getText().isEmpty())
{
int number = Integer.parseInt(numberCalc.getText());
if (calcOperation == 1)
{
int calculate = currentCalc + number;
numberCalc.setText(Integer.toString(calculate));
}
else if (calcOperation == 2)
{
int calculate = currentCalc – number;
numberCalc.setText(Integer.toString(calculate));
}
}
}
});
buttonPanel.add(addButton);
buttonPanel.add(subButton);
buttonPanel.add(equalsButton);
guiFrame.setVisible(true);
}
//All the buttons are following the same pattern
//so create them all in one place.
private void addButton(Container parent, String name)
{
JButton but = new JButton(name);
but.setActionCommand(name);
but.addActionListener(this);
parent.add(but);
}
//As all the buttons are doing the same thing it’s
//easier to make the class implement the ActionListener
//interface and control the button clicks from one place
@Override
public void actionPerformed(ActionEvent event)
{
//get the Action Command text from the button
String action = event.getActionCommand();
//set the text using the Action Command text
numberCalc.setText(action);
}
private class OperatorAction implements ActionListener
{
private int operator;
public OperatorAction(int operation)
{
operator = operation;
}
public void actionPerformed(ActionEvent event)
{
currentCalc = Integer.parseInt(numberCalc.getText());
calcOperation = operator;
}
}
}