This is a java program that runs on the Eclipse.

It is a calculator with a plus sign.

You are required to add multiplication and subtraction buttons to the application

Test to make sure all functionality works as you expect.

Here is the Java code.

package calculator;

import javax.swing.*; import java.awt.Color; import java.awt.event.*;

public class CalcPanel extends JPanel implements ActionListener { String num1=""; String num2=""; String operator=""; boolean usingFirst=true; double total=0; JTextField display; JButton b1; JButton b2; JButton b3; JButton b4; JButton b5; JButton b6; JButton b7; JButton b8; JButton b9; JButton b0; JButton bdec; JButton bclear; JButton bequals; JButton bplus; public CalcPanel() { this.setBackground(Color.white); setLayout(null); display=new JTextField();

b1=new JButton("1"); b2=new JButton("2"); b3=new JButton("3"); b4=new JButton("4"); b5=new JButton("5"); b6=new JButton("6"); b7=new JButton("7"); b8=new JButton("8"); b9=new JButton("9"); b0=new JButton("0"); bdec=new JButton("."); bclear=new JButton("C"); bequals = new JButton( "="); bplus=new JButton("+");

display.setBounds(0,0,205,50); b1.setBounds(0,200,50,50); b2.setBounds(50,200,50,50); b3.setBounds(100,200,50,50); bplus.setBounds(154,200,50,50);

b4.setBounds(0,150,50,50); b5.setBounds(50,150,50,50); b6.setBounds(100,150,50,50);

b7.setBounds(0,100,50,50); b8.setBounds(50,100,50,50); b9.setBounds(100,100,50,50); b0.setBounds(0,250,50,50); bdec.setBounds(50,250,50,50); bclear.setBounds(100,250,50,50); bequals.setBounds(154,250,50,50); add(b1); add(b2); add(b3); add(b4); add(b5); add(b6); add(b7); add(b8); add(b9); add(b0); add(bdec); add(display); add(bclear); add(bequals); add(bplus);

b1.addActionListener(this); b2.addActionListener(this); b3.addActionListener(this); b4.addActionListener(this); b5.addActionListener(this); b6.addActionListener(this); b7.addActionListener(this); b8.addActionListener(this); b9.addActionListener(this); b0.addActionListener(this); bequals.addActionListener(this); bplus.addActionListener(this); bclear.addActionListener(this); bdec.addActionListener(this); } public void actionPerformed(ActionEvent e){ String s=e.getActionCommand(); if(s.equals("1")||s.equals("2")||s.equals("3")||s.equals("4")|| s.equals("5")||s.equals("6")||s.equals("7")||s.equals("8")|| s.equals("9")||s.equals("0")||s.equals(".")) { if(usingFirst) { num1=num1+s; display.setText(num1); } else { num2=num2+s; display.setText(num2); } } if(s.equals("+")) { usingFirst=false; operator="+"; } if(s.equals("=")) { switch(operator){ case "+": total=Double.parseDouble(num1)+Double.parseDouble(num2); display.setText( ""+total ); break; } usingFirst=true; num1=""; num2=""; operator=""; } if(s.equals("C")) { display.setText( "" ); usingFirst=true; num1=""; num2=""; total=0; } } }