Our calculator will have the GUI similar to that of the Calculator app of the Wi

Question

Our calculator will have the GUI similar to that of the Calculator app of the Window operating system. The buttons and panels must be placed exactly as in the above figure. Your app must match the following features with the expected sequence of actions of the users is enter the first number enter an operator (/, *, -, +) enter the second number enter the operator = enter the operator C (for clearing or resetting the calculator) this cycle then can be repeated forever Your calculator does not need to produce a result if the user enters an illegal sequence of actions, such as: 223 + 3 + 3, or 33+++. In this case, there is no requirement on what the app should display. But it should not crash. After the user enters C, all the previous actions will be erased, and the app will behave as if it is newly launched. The first panel should display the input produced by the user. When the user hit the C button, this panel should not display anything (that is, it displays an empty string). The second panel displays the result of the computation when the user presses =. In any other situations, it displays nothing. Even though the input are integers only, the results may be real number (for example, 3/2 = 1.5). So the second panel must display real numbers. The four "dummy buttons" (the buttons with no symbols) are there to fill the JFrame only, nothing should happen when they are pressed.

Explanation / Answer

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)
{
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);
  
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;
}
  
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;
}

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;}
}
  
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);
}
}
  
  
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;
}
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;
}
  
cl.displayLabel.setText(MyCalculator.getFormattedText(temp));
}
}
  
  
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;
}
}
}
  
  
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();
if(opText.equals("Backspc"))
{
String tempText=backSpace(cl.displayLabel.getText());
if(tempText.equals(""))   
cl.displayLabel.setText("0");
else   
cl.displayLabel.setText(tempText);
return;
}

if(opText.equals("C"))   
{
cl.number=0.0; cl.op=' '; cl.memValue=0.0;
cl.memLabel.setText(" ");
}

cl.displayLabel.setText("0");cl.setClear=true;
}
}

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