Question

Hi, please could someone be of assistance with this assignment for me. Thank you

The objective of this assignment is to practice the use of control objects in GUI design.
You are required to create a 4- function calculator. See pic below.

Calculator.png

The calculator should have buttons for all 10 numbers, the decimal point, the four operations (+,-,/,*), an equal “=” button, a "main display" (TextBox or RichTextBot), a backspace button and a clear “C” button.
When you create your controls, you need to give them proper names (e.g. ButtonOne, ButtonResult, ButtonClear,etc)
The only programming in this assignment is

• To make sure that whenever a number button is clicked, that number will appear in the mainDiaply
  • e.g. if the user click 3, then the number 3 will appear. If the user then clicks 4, then 34 will appear.
  • make sure that include fractional numbers like "5.44", this means that you need to activate the '.' button
• If the user clicks on the 'C' button, the main Display will be cleared

Answer 1

import java.awt.event.*;
import javax.swing.*;
public class CalcGUI extends JFrame implements ActionListener {
   static JFrame frame;
   //for result display
   static JTextField textField;
   String str0, str1, str2;
   CalcGUI()
   {
       str0 = str1 = str2 = "";
   }
   //driver programme
   public static void main(String args[])
   {
       frame = new JFrame("CalcGUI");
       CalcGUI calc = new CalcGUI();
       textField = new JTextField(16);
       textField.setEditable(false);
       //for buttons
       JButton button0, button1, button2, button3, button4, button5, button6, button7, button8, button9, ButtonPlus, ButtonSubstract, ButtonDivition, ButtonMultiplication, ButtonDot, ButtonClear, buttonEqual;
       //intilizing buttons
       button0 = new JButton("0");
       button1 = new JButton("1");
       button2 = new JButton("2");
       button3 = new JButton("3");
       button4 = new JButton("4");
       button5 = new JButton("5");
       button6 = new JButton("6");
       button7 = new JButton("7");
       button8 = new JButton("8");
       button9 = new JButton("9");
       buttonEqual = new JButton("=");
       ButtonPlus = new JButton("+");
       ButtonSubstract = new JButton("-");
       ButtonDivition = new JButton("/");
       ButtonMultiplication = new JButton("*");
       ButtonClear = new JButton("C");
       ButtonDot = new JButton(".");
       JPanel panel = new JPanel();
       //adding action listeners to the buttons
       ButtonMultiplication.addActionListener(calc);
       ButtonDivition.addActionListener(calc);
       ButtonSubstract.addActionListener(calc);
       ButtonPlus.addActionListener(calc);
       button9.addActionListener(calc);
       button8.addActionListener(calc);
       button7.addActionListener(calc);
       button6.addActionListener(calc);
       button5.addActionListener(calc);
       button4.addActionListener(calc);
       button3.addActionListener(calc);
       button2.addActionListener(calc);
       button1.addActionListener(calc);
       button0.addActionListener(calc);
       ButtonDot.addActionListener(calc);
       ButtonClear.addActionListener(calc);
       buttonEqual.addActionListener(calc);
       //adding buttons to the panel
       panel.add(textField);
       panel.add(ButtonPlus);
       panel.add(button1);
       panel.add(button2);
       panel.add(button3);
       panel.add(ButtonSubstract);
       panel.add(button4);
       panel.add(button5);
       panel.add(button6);
       panel.add(ButtonMultiplication);
       panel.add(button7);
       panel.add(button8);
       panel.add(button9);
       panel.add(ButtonDivition);
       panel.add(ButtonDot);
       panel.add(button0);
       panel.add(ButtonClear);
       panel.add(buttonEqual);
       frame.add(panel);
       frame.setSize(200, 220);
       frame.show();
   }
   //this is the function which will perform when user clicks on it
   public void actionPerformed(ActionEvent e)
   {
       String actionCommand = e.getActionCommand();
       //if user press other than operators we need to append
       if ((actionCommand.charAt(0) >= '0' && actionCommand.charAt(0) <= '9') || actionCommand.charAt(0) == '.') {
           if (!str1.equals(""))
               str2 = str2 + actionCommand;
           else
               str0 = str0 + actionCommand;
           textField.setText(str0 + str1 + str2);
       }
       //this is for clear button
       else if (actionCommand.charAt(0) == 'C') {
           str0 = str1 = str2 = "";
           textField.setText(str0 + str1 + str2);
       }
       //this is the for calculation part
       else if (actionCommand.charAt(0) == '=') {
           double result;
           if (str1.equals("+"))
               result = (Double.parseDouble(str0) + Double.parseDouble(str2));
           else if (str1.equals("-"))
               result = (Double.parseDouble(str0) - Double.parseDouble(str2));
           else if (str1.equals("/"))
               result = (Double.parseDouble(str0) / Double.parseDouble(str2));
           else
               result = (Double.parseDouble(str0) * Double.parseDouble(str2));
           textField.setText(str0 + str1 + str2 + "=" + result);
           str0 = Double.toString(result);
           str1 = str2 = "";
       }
       else {
           if (str1.equals("") || str2.equals(""))
               str1 = actionCommand;
           else {
               double result;
               if (str1.equals("+"))
                   result = (Double.parseDouble(str0) + Double.parseDouble(str2));
               else if (str1.equals("-"))
                   result = (Double.parseDouble(str0) - Double.parseDouble(str2));
               else if (str1.equals("/"))
                   result = (Double.parseDouble(str0) / Double.parseDouble(str2));
               else
                   result = (Double.parseDouble(str0) * Double.parseDouble(str2));
               str0 = Double.toString(result);
               str1 = actionCommand;
               str2 = "";
           }
           textField.setText(str0 + str1 + str2);
       }
   }
}