a) Design a GUI for a calculator and implement the callback functions for the ba

Question

a) Design a GUI for a calculator and implement the callback functions for the basic operations (addition, subtraction, multiplication, and division). Your GUI should have: i) Pushbuttons for the numerals 0 to 9 ii) Pushbuttons for the basic operators for addition, subtraction, multiplication, and division. Pushbuttons for calculate (=) and clear. Static text for showing the current performed operations and final result (label it resultScreen). resultScreen should always show the list of operations the user would like to perform and once the calculate (=) button is pressed the list of operations should be performed and the final result is evaluated. Keep in mind that you have to follow the order of operations PEMDAS (Parentheses, Exponents, Multiplication, Division, Addition, Subtraction). iv)

Explanation / Answer

import javax.swing.*; import java.awt.*; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; public class Frame extends JFrame { private double tempNumbers1 = 0; private double tempNumbers2 = 0; private byte function = -1; private JTextField resultJText; public Frame() { JButton[] numberButtons = new JButton[10]; for ( int i = 9; i >= 0; i--) { numberButtons[i] = new JButton(Integer.toString(i)); } JButton enterButton = new JButton("Enter"); JButton cButton = new JButton("C"); JButton multiplyButton = new JButton("*"); JButton divideButton = new JButton("/"); JButton addButton = new JButton("+"); JButton substractButton = new JButton("-"); resultJText = new JTextField(); resultJText.setPreferredSize(new Dimension(160, 20)); resultJText.setBackground(Color.WHITE); resultJText.setEnabled(false); resultJText.setHorizontalAlignment(4); resultJText.setDisabledTextColor(Color.BLACK); JPanel motherPanel = new JPanel(); motherPanel.setLayout(new BoxLayout(motherPanel, BoxLayout.Y_AXIS)); JPanel textPanel = new JPanel(); textPanel.setPreferredSize(new Dimension(160, 20)); textPanel.add(resultJText); JPanel numberButtonsPanel = new JPanel(); numberButtonsPanel.setPreferredSize(new Dimension(160, 100)); for(int i = 9; i>=0; i--) { numberButtonsPanel.add(numberButtons[i]); } JPanel functionButtonPanel = new JPanel(); functionButtonPanel.setPreferredSize(new Dimension(160, 35)); functionButtonPanel.add(enterButton); functionButtonPanel.add(cButton); functionButtonPanel.add(multiplyButton); functionButtonPanel.add(divideButton); functionButtonPanel.add(addButton); functionButtonPanel.add(substractButton); numberButtonsAction[] numberButtonActions = new numberButtonsAction[10]; for ( int i = 0; i < 10; i++ ) { numberButtonActions[i] = new numberButtonsAction(numberButtons[i]); numberButtons[i].addActionListener(numberButtonActions[i]); } EnterButton enter = new EnterButton(); enterButton.addActionListener(enter); CButton c = new CButton(); cButton.addActionListener(c); MultiplyButton multiply = new MultiplyButton(); multiplyButton.addActionListener(multiply); DivideButton divide = new DivideButton(); divideButton.addActionListener(divide); AddButton add = new AddButton(); addButton.addActionListener(add); SubtractButton subtract = new SubtractButton(); substractButton.addActionListener(subtract); motherPanel.add(textPanel); motherPanel.add(numberButtonsPanel); motherPanel.add(functionButtonPanel); add(motherPanel); setTitle("ButtonTest"); setSize(180, 290); setLocationByPlatform(true); setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE); setVisible(true); } private class numberButtonsAction implements ActionListener { private String c; public numberButtonsAction(JButton a) { this.c = a.getText(); } public void actionPerformed(ActionEvent e) { if (!resultJText.getText().equals("0.0")) { resultJText.setText(resultJText.getText() + c); } else { resultJText.setText(""); actionPerformed(e); } } } private class EnterButton implements ActionListener { @Override public void actionPerformed(ActionEvent e) { tempNumbers2 = Double.parseDouble(resultJText.getText()); if (function == 0) { resultJText.setText(Double.toString((Math.round((tempNumbers1 / tempNumbers2) * 100)) / 100)); } else if (function == 1) { resultJText.setText(Double.toString(tempNumbers1 * tempNumbers2)); } else if (function == 2) { resultJText.setText(Double.toString(tempNumbers2 + tempNumbers1)); } else if (function == 3) { resultJText.setText(Double.toString(tempNumbers1 - tempNumbers2)); } else { resultJText.setText(String.valueOf(tempNumbers1)); } tempNumbers1 = Double.parseDouble(resultJText.getText()); } } private class CButton implements ActionListener { @Override public void actionPerformed(ActionEvent e) { resultJText.setText(""); tempNumbers1 = 0; tempNumbers2 = 0; function = -1; } } private class DivideButton implements ActionListener { @Override public void actionPerformed(ActionEvent e) { if (tempNumbers1 == 0) { tempNumbers1 = Double.parseDouble(resultJText.getText()); resultJText.setText(""); } else { tempNumbers2 = Double.parseDouble(resultJText.getText()); resultJText.setText(""); } function = 0; } } private class MultiplyButton implements ActionListener { @Override public void actionPerformed(ActionEvent e) { if (tempNumbers1 == 0) { tempNumbers1 = Double.parseDouble(resultJText.getText()); resultJText.setText(""); } else { tempNumbers2 = Double.parseDouble(resultJText.getText()); resultJText.setText(""); } function = 1; } } private class AddButton implements ActionListener { @Override public void actionPerformed(ActionEvent e) { if (tempNumbers1 == 0) { tempNumbers1 = Double.parseDouble(resultJText.getText()); resultJText.setText(""); } else { tempNumbers2 = Double.parseDouble(resultJText.getText()); resultJText.setText(""); } function = 2; } } private class SubtractButton implements ActionListener { @Override public void actionPerformed(ActionEvent e) { if (tempNumbers1 == 0) { tempNumbers1 = Double.parseDouble(resultJText.getText()); resultJText.setText(""); } else { tempNumbers2 = Double.parseDouble(resultJText.getText()); resultJText.setText(""); } function = 3; } } }

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