Calculators

The following is for a simple calculator; a scientific calculator is more complicated. I will assume the user will press keys to have a number appear on the display; to (for example) add this with another number, the user presses "+" followed by the second number, followed by "=".

You would use a visual interface, with the number display, the digits, the equal sign, and a few operations (plus, minus, multiply, divide, ...).

As soon as the user types the second number, the first number will disappear from the screen; therefore, you have to save it into some variable.

Every time a key is pressed, you have to decide whether you should add a digit to the number in the display (if it is a digit, or a period), or whether to do a calculation (if it is +, -, *, /). If it is an operation, do the operation (conditionally, depending on the selected operation), and replace the number displayed by the new value.

This is my sample code using JAVA:

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

import javax.swing.event.*;

import java.text.*;

import javax.swing.border.*;

class Calc extends JFrame implements ActionListener

{

private static final Font BIGGER_FONT = new Font("Tahoma", Font.BOLD, 13);

private JRadioButton decimalb,binaryb,octalb,hexab,enableb, disableb;

private JTextField _displayField, decimalTF, binaryTF, octalTF, hexaTF;

private JLabel decimalL,binaryL,octalL,hexaL;

private JButton exitb, convertb, clearb, backSpace, b9, b8, b7, b6, b5, b4, b3, b2, b1, b0, b11, b12, b13;

private JButton b14, b15, b16, b17, b18, b19, b20, b21, b22, b23, b24, b25;

private JPanel cbPanel, upperButtonPanel;

private ButtonGroup group, group2;

private boolean pluz = false;

private boolean subs = false;

private boolean multiply = false;

private boolean divide = false;

private boolean _startNumber = true;

private boolean dotCheck = false;

private String firstValue, Secondvalue;

private String _previousOp = "=";

private DecimalFormat df = new DecimalFormat("###,###,###.##");

private CalculatorLogic calLogic = new CalculatorLogic();

public static void main(String[] args) {

try {

UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());

} catch (Exception unused) {

;

}

Calc window = new Calc();

window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

window.setVisible(true);

}

public Calc()

{

super("Calculator With Number System Converter");

_displayField = new JTextField("", 15);

_displayField.setHorizontalAlignment(JTextField.RIGHT);

_displayField.setFont(BIGGER_FONT);

_displayField.setEditable(false);

_displayField.setBackground(Color.WHITE);

upperButtonPanel = new JPanel();

upperButtonPanel.setLayout(new FlowLayout());

upperButtonPanel.setBackground(Color.lightGray);

upperButtonPanel.setPreferredSize(new Dimension(170, 300));

decimalb = new JRadioButton("Decimal", false);

binaryb = new JRadioButton("Binary", false);

octalb = new JRadioButton("Octal", false);

hexab = new JRadioButton("Hexadecimal", false);

decimalb.setFont(BIGGER_FONT);

binaryb.setFont(BIGGER_FONT);

octalb.setFont(BIGGER_FONT);

hexab.setFont(BIGGER_FONT);

decimalb.addActionListener(this);

binaryb.addActionListener(this);

octalb.addActionListener(this);

hexab.addActionListener(this);

group = new ButtonGroup();

group.add(decimalb);

group.add(binaryb);

group.add(octalb);

group.add(hexab);

upperButtonPanel.add(decimalb);

upperButtonPanel.add(binaryb);

upperButtonPanel.add(octalb);

upperButtonPanel.add(hexab);

upperButtonPanel.setVisible(false);

JPanel panel = new JPanel(new GridLayout(10, 1));

panel.setPreferredSize(new Dimension(300, 300));

panel.setBorder(new BevelBorder(BevelBorder.LOWERED));

decimalTF = new JTextField(20);

binaryTF = new JTextField(20);

octalTF = new JTextField(20);

hexaTF = new JTextField(20);

decimalTF.setEditable(false);

binaryTF.setEditable(false);

octalTF.setEditable(false);

hexaTF.setEditable(false);

decimalTF.setBackground(Color.WHITE);

binaryTF.setBackground(Color.WHITE);

octalTF.setBackground(Color.WHITE);

hexaTF.setBackground(Color.WHITE);

decimalTF.setFont(BIGGER_FONT);

binaryTF.setFont(BIGGER_FONT);

octalTF.setFont(BIGGER_FONT);

hexaTF.setFont(BIGGER_FONT);

decimalTF.setVisible(false);

binaryTF.setVisible(false);

octalTF.setVisible(false);

hexaTF.setVisible(false);

decimalL = new JLabel("Decimal Value");

binaryL = new JLabel("Binary Value");

octalL = new JLabel("Octal Value");

hexaL = new JLabel("Hexadecimal Value");

decimalL.setFont(BIGGER_FONT);

binaryL.setFont(BIGGER_FONT);

octalL.setFont(BIGGER_FONT);

hexaL.setFont(BIGGER_FONT);

decimalL.setVisible(false);

binaryL.setVisible(false);

octalL.setVisible(false);

hexaL.setVisible(false);

panel.add(decimalL);

panel.add(decimalTF);

panel.add(binaryL);

panel.add(binaryTF);

panel.add(octalL);

panel.add(octalTF);

panel.add(hexaL);

panel.add(hexaTF);

upperButtonPanel.add(panel);

add(upperButtonPanel, BorderLayout.NORTH);

JPanel buttonPanel = new JPanel();

buttonPanel.setLayout(new GridLayout(5, 2, 5, 5));

buttonPanel.setBackground(Color.lightGray);

buttonPanel.setBorder(new BevelBorder(BevelBorder.LOWERED));

b9 = new JButton("9");

b8 = new JButton("8");

b7 = new JButton("7");

b6 = new JButton("6");

b5 = new JButton("5");

b4 = new JButton("4");

b3 = new JButton("3");

b2 = new JButton("2");

b1 = new JButton("1");

b0 = new JButton("0");

b11 = new JButton(".");

b12 = new JButton("/");

b13 = new JButton("*");

b14 = new JButton("-");

b15 = new JButton("+");

b16 = new JButton("A");

b17 = new JButton("B");

b18 = new JButton("C");

b19 = new JButton("D");

b20 = new JButton("E");

b21 = new JButton("F");

b22 = new JButton("=");

b23 = new JButton("sqrt");

b24 = new JButton("x\u00B2");

b25 = new JButton("x\u00B3");

b1.setFont(BIGGER_FONT);

b2.setFont(BIGGER_FONT);

b3.setFont(BIGGER_FONT);

b4.setFont(BIGGER_FONT);

b5.setFont(BIGGER_FONT);

b6.setFont(BIGGER_FONT);

b7.setFont(BIGGER_FONT);

b8.setFont(BIGGER_FONT);

b9.setFont(BIGGER_FONT);

b0.setFont(BIGGER_FONT);

b11.setFont(BIGGER_FONT);

b12.setFont(BIGGER_FONT);

b13.setFont(BIGGER_FONT);

b14.setFont(BIGGER_FONT);

b15.setFont(BIGGER_FONT);

b16.setFont(BIGGER_FONT);

b17.setFont(BIGGER_FONT);

b18.setFont(BIGGER_FONT);

b19.setFont(BIGGER_FONT);

b20.setFont(BIGGER_FONT);

b21.setFont(BIGGER_FONT);

b22.setFont(BIGGER_FONT);

b23.setFont(BIGGER_FONT);

b24.setFont(BIGGER_FONT);

b25.setFont(BIGGER_FONT);

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);

b11.addActionListener(this);

b12.addActionListener(this);

b13.addActionListener(this);

b14.addActionListener(this);

b15.addActionListener(this);

b16.addActionListener(this);

b17.addActionListener(this);

b18.addActionListener(this);

b19.addActionListener(this);

b20.addActionListener(this);

b21.addActionListener(this);

b22.addActionListener(this);

b23.addActionListener(this);

b24.addActionListener(this);

b25.addActionListener(this);

b16.setEnabled(false);

b17.setEnabled(false);

b18.setEnabled(false);

b19.setEnabled(false);

b20.setEnabled(false);

b21.setEnabled(false);

buttonPanel.add(b7);

buttonPanel.add(b8);

buttonPanel.add(b9);

buttonPanel.add(b12);

buttonPanel.add(b13);

buttonPanel.add(b15);

buttonPanel.add(b4);

buttonPanel.add(b5);

buttonPanel.add(b6);

buttonPanel.add(b15);

buttonPanel.add(b14);

buttonPanel.add(b11);

buttonPanel.add(b1);

buttonPanel.add(b2);

buttonPanel.add(b3);

buttonPanel.add(b0);

buttonPanel.add(b22);

buttonPanel.add(b16);

buttonPanel.add(b17);

buttonPanel.add(b18);

buttonPanel.add(b11);

buttonPanel.add(b23);

buttonPanel.add(b19);

buttonPanel.add(b20);

buttonPanel.add(b21);

buttonPanel.add(b24);

buttonPanel.add(b25);

add(buttonPanel);

group2 = new ButtonGroup();

disableb = new JRadioButton("Disable Converter", true);

enableb = new JRadioButton("Enable Converter", false);

disableb.setFont(BIGGER_FONT);

enableb.setFont(BIGGER_FONT);

disableb.addActionListener(this);

enableb.addActionListener(this);

group2.add(disableb);

group2.add(enableb);

cbPanel = new JPanel(new GridLayout(3, 3));

cbPanel.setBorder(new BevelBorder(BevelBorder.RAISED));

cbPanel.add(disableb);

cbPanel.add(enableb);

convertb = new JButton("Convert");

clearb = new JButton("Clear");

exitb = new JButton("Exit");

backSpace = new JButton("BackSpace");

convertb.addActionListener(this);

clearb.addActionListener(this);

exitb.addActionListener(this);

backSpace.addActionListener(this);

convertb.setFont(BIGGER_FONT);

clearb.setFont(BIGGER_FONT);

exitb.setFont(BIGGER_FONT);

backSpace.setFont(BIGGER_FONT);

cbPanel.add(convertb);

cbPanel.add(clearb);

cbPanel.add(backSpace);

cbPanel.add(exitb);

convertb.setEnabled(false);

JPanel content2 = new JPanel();

content2.setLayout(new BorderLayout(5, 5));

content2.add(_displayField, BorderLayout.NORTH);

content2.add(buttonPanel , BorderLayout.CENTER);

content2.add(cbPanel, BorderLayout.SOUTH);

add(content2, BorderLayout.SOUTH);

this.setSize(340, 300);

this.setResizable(false);

this.setLocationRelativeTo(null);

}

public void actionPerformed(ActionEvent e)

{

try{

if(decimalb.isSelected())

{

b0.setEnabled(true);

b1.setEnabled(true);

b2.setEnabled(true);

b3.setEnabled(true);

b4.setEnabled(true);

b5.setEnabled(true);

b6.setEnabled(true);

b7.setEnabled(true);

b8.setEnabled(true);

b9.setEnabled(true);

b16.setEnabled(false);

b17.setEnabled(false);

b18.setEnabled(false);

b19.setEnabled(false);

b20.setEnabled(false);

b21.setEnabled(false);

}

else if(binaryb.isSelected())

{

b2.setEnabled(false);

b3.setEnabled(false);

b4.setEnabled(false);

b5.setEnabled(false);

b6.setEnabled(false);

b7.setEnabled(false);

b8.setEnabled(false);

b9.setEnabled(false);

b16.setEnabled(false);

b17.setEnabled(false);

b18.setEnabled(false);

b19.setEnabled(false);

b20.setEnabled(false);

b21.setEnabled(false);

}

else if(octalb.isSelected())

{

b0.setEnabled(true);

b1.setEnabled(true);

b2.setEnabled(true);

b3.setEnabled(true);

b4.setEnabled(true);

b5.setEnabled(true);

b6.setEnabled(true);

b7.setEnabled(true);

b16.setEnabled(false);

b17.setEnabled(false);

b18.setEnabled(false);

b19.setEnabled(false);

b20.setEnabled(false);

b21.setEnabled(false);

b8.setEnabled(false);

b9.setEnabled(false);

}

else if(hexab.isSelected())

{

b0.setEnabled(true);

b1.setEnabled(true);

b2.setEnabled(true);

b3.setEnabled(true);

b4.setEnabled(true);

b5.setEnabled(true);

b6.setEnabled(true);

b7.setEnabled(true);

b8.setEnabled(true);

b9.setEnabled(true);

b16.setEnabled(true);

b17.setEnabled(true);

b18.setEnabled(true);

b19.setEnabled(true);

b20.setEnabled(true);

b21.setEnabled(true);

}

if((e.getActionCommand().equals("Convert")) && decimalb.isSelected())

{

String input, bin="",oct="",hex="";

int rem,rem2,rem3,len;

char x;

input = _displayField.getText().trim();

try{

if(input.equals(""))

throw new Exception("Error");

else

len = input.length();

int num = Integer.parseInt(input);

while(num>0)

{

rem = num%2;

num/=2;

bin = rem + bin;

}

binaryTF.setText(bin);

decimalTF.setText(input);

int num2 = Integer.parseInt(input);

while(num2>0)

{

rem2 = num2%8;

oct = rem2 + oct;

num2/=8;

}

octalTF.setText(oct);

int num3 = Integer.parseInt(input);

while(num3>0)

{

rem3 = num3%16;

if(rem3<10)

hex = rem3 + hex;

else if(rem3 0)

{

JOptionPane.showMessageDialog(null,"Can't divide by zero", "Error Message", JOptionPane.ERROR_MESSAGE);

return 0;

}

else

return (a / b);

}

public double stringToDouble(String a)

{

return Double.parseDouble(a);

}

}

answer. you can use it if you have long answer and need to do something to it.

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Press [DSP] and select .

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