Notes

Graphics Calculator
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class Calculator extends JFrame implements ActionListener {
private JTextField display;
private double num1, num2, result;
private char operator;

public Calculator() {
setUndecorated(true);
setSize(350, 500);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLocationRelativeTo(null);


JPanel titleBar = new JPanel() {
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
GradientPaint gradient = new GradientPaint(0, 0, Color.PINK, getWidth(), 0, Color.ORANGE);
g2d.setPaint(gradient);
g2d.fillRect(0, 0, getWidth(), getHeight());
}
};
titleBar.setPreferredSize(new Dimension(getWidth(), 40));
titleBar.setLayout(new BorderLayout());


JLabel titleLabel = new JLabel(" Calculator");
titleLabel.setFont(new Font("Arial", Font.BOLD, 18));
titleLabel.setForeground(Color.WHITE);
titleBar.add(titleLabel, BorderLayout.WEST);


JButton closeButton = new JButton("X");
closeButton.setForeground(Color.WHITE);
closeButton.setBackground(Color.RED);
closeButton.setFocusPainted(false);
closeButton.setBorderPainted(false);
closeButton.addActionListener(e -> System.exit(0));
titleBar.add(closeButton, BorderLayout.EAST);

display = new JTextField();
display.setEditable(false);
display.setFont(new Font("Arial", Font.BOLD, 28));
display.setHorizontalAlignment(JTextField.RIGHT);
display.setBackground(Color.WHITE);
display.setForeground(Color.BLACK);

JPanel mainPanel = new JPanel() {
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
GradientPaint gradient = new GradientPaint(0, 0, Color.CYAN, getWidth(), getHeight(), Color.BLUE);
g2d.setPaint(gradient);
g2d.fillRect(0, 0, getWidth(), getHeight());
}
};
mainPanel.setLayout(new BorderLayout(10, 10));


JPanel buttonPanel = new JPanel();
buttonPanel.setLayout(new GridLayout(5, 4, 10, 10));
buttonPanel.setOpaque(false);

String[] buttons = {
"C", "√", "x²", "/",
"7", "8", "9", "x",
"4", "5", "6", "-",
"1", "2", "3", "+",
"0", ".", "=",
};

for (String text : buttons) {
JButton button = new JButton(text);
button.setFont(new Font("Arial", Font.BOLD, 18));
button.setBackground(Color.LIGHT_GRAY);
button.setForeground(Color.DARK_GRAY);
button.setFocusPainted(false);
button.addActionListener(this);
buttonPanel.add(button);
}


mainPanel.add(display, BorderLayout.NORTH);
mainPanel.add(buttonPanel, BorderLayout.CENTER);


getContentPane().setLayout(new BorderLayout());
getContentPane().add(titleBar, BorderLayout.NORTH);
getContentPane().add(mainPanel, BorderLayout.CENTER);

setVisible(true);
}

@Override
public void actionPerformed(ActionEvent e) {
String command = e.getActionCommand();

switch (command) {
case "C":
display.setText("");
num1 = num2 = result = 0;
operator = '';
break;
case "√":
num1 = Double.parseDouble(display.getText());
result = Math.sqrt(num1);
display.setText(String.valueOf(result));
break;
case "x²":
num1 = Double.parseDouble(display.getText());
result = Math.pow(num1, 2);
display.setText(String.valueOf(result));
break;
case "+":
case "-":
case "x":
case "/":
num1 = Double.parseDouble(display.getText());
operator = command.charAt(0);
display.setText("");
break;
case "=":
num2 = Double.parseDouble(display.getText());
calculateResult();
display.setText(String.valueOf(result));
break;
case ".":
if (!display.getText().contains(".")) {
display.setText(display.getText() + ".");
}
break;
default:
display.setText(display.getText() + command);
break;
}
}

private void calculateResult() {
switch (operator) {
case '+': result = num1 + num2; break;
case '-': result = num1 - num2; break;
case 'x': result = num1 * num2; break;
case '/': result = num2 != 0 ? num1 / num2 : 0; break;
}
}

public static void main(String[] args) {
new Calculator();
}
}



Normal Calculator
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class Calculator implements ActionListener {

JFrame frame;
JTextField textfield;
JButton[] numberButtons = new JButton[10];
JButton[] functionButtons = new JButton[9];
JButton addButton, subButton, mulButton, divButton;
JButton decButton, equButton, delButton, clrButton, negButton;
JPanel panel;

Font myFont = new Font("Ink Free", Font.BOLD, 30);

double num1 = 0, num2 = 0, result = 0;
char operator;

Calculator() {
frame = new JFrame("Calculator");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(420, 550);
frame.setLayout(null);

textfield = new JTextField();
textfield.setBounds(50, 25, 300, 50);
textfield.setFont(myFont);
textfield.setEditable(false);

addButton = new JButton("+");
subButton = new JButton("-");
mulButton = new JButton("*");
divButton = new JButton("/");
decButton = new JButton(".");
equButton = new JButton("=");
delButton = new JButton("Delete");
negButton = new JButton("(-)");
clrButton = new JButton("Clear");

functionButtons[0] = addButton;
functionButtons[1] = subButton;
functionButtons[2] = mulButton;
functionButtons[3] = divButton;
functionButtons[4] = decButton;
functionButtons[5] = equButton;
functionButtons[6] = delButton;
functionButtons[7] = clrButton;
functionButtons[8] = negButton;

for (int i = 0; i < 9; i++) {
functionButtons[i].addActionListener(this);
functionButtons[i].setFont(myFont);
functionButtons[i].setFocusable(false);
}

for (int i = 0; i < 10; i++) {
numberButtons[i] = new JButton(String.valueOf(i));
numberButtons[i].addActionListener(this);
numberButtons[i].setFont(myFont);
numberButtons[i].setFocusable(false);
}

negButton.setBounds(50, 430, 100, 50);
delButton.setBounds(150, 430, 100, 50);
clrButton.setBounds(250, 430, 100, 50);

panel = new JPanel();
panel.setBounds(50, 100, 300, 300);
panel.setLayout(new GridLayout(4, 4, 10, 10));

panel.add(numberButtons[1]);
panel.add(numberButtons[2]);
panel.add(numberButtons[3]);
panel.add(addButton);
panel.add(numberButtons[4]);
panel.add(numberButtons[5]);
panel.add(numberButtons[6]);
panel.add(subButton);
panel.add(numberButtons[7]);
panel.add(numberButtons[8]);
panel.add(numberButtons[9]);
panel.add(mulButton);
panel.add(decButton);
panel.add(numberButtons[0]);
panel.add(equButton);
panel.add(divButton);

frame.add(panel);
frame.add(negButton);
frame.add(delButton);
frame.add(clrButton);
frame.add(textfield);

frame.setVisible(true);
}

public static void main(String[] args) {
Calculator c = new Calculator();
}

@Override
public void actionPerformed(ActionEvent e) {
for (int i = 0; i < 10; i++) {
if (e.getSource() == numberButtons[i]) {
textfield.setText(textfield.getText().concat(String.valueOf(i)));
}
}
if (e.getSource() == decButton) {
textfield.setText(textfield.getText().concat("."));
}
if (e.getSource() == addButton) {
num1 = Double.parseDouble(textfield.getText());
operator = '+';
textfield.setText("");
}
if (e.getSource() == subButton) {
num1 = Double.parseDouble(textfield.getText());
operator = '-';
textfield.setText("");
}
if (e.getSource() == mulButton) {
num1 = Double.parseDouble(textfield.getText());
operator = '*';
textfield.setText("");
}
if (e.getSource() == divButton) {
num1 = Double.parseDouble(textfield.getText());
operator = '/';
textfield.setText("");
}
if (e.getSource() == equButton) {
num2 = Double.parseDouble(textfield.getText());
switch (operator) {
case '+':
result = num1 + num2;
break;
case '-':
result = num1 - num2;
break;
case '*':
result = num1 * num2;
break;
case '/':
result = num1 / num2;
break;
}
textfield.setText(String.valueOf(result));
num1 = result;
}
if (e.getSource() == clrButton) {
textfield.setText("");
}
if (e.getSource() == delButton) {
String string = textfield.getText();
textfield.setText(string.length() > 0 ? string.substring(0, string.length() - 1) : "");
}
if (e.getSource() == negButton) {
double temp = Double.parseDouble(textfield.getText());
temp *= -1;
textfield.setText(String.valueOf(temp));
}
}
}