Java GUI Basics with Swing

import javax.swing.*;

public class MyWindow {
    public static void main(String[] args) {
        JFrame frame = new JFrame("My First GUI");
        frame.setSize(400, 300);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLocationRelativeTo(null); // Center on screen
        frame.setVisible(true);
    }
}

JLabel label = new JLabel("Enter your name:");
JTextField textField = new JTextField(20);
JButton button = new JButton("Submit");
JTextArea textArea = new JTextArea(5, 20);
JCheckBox checkBox = new JCheckBox("I agree");
JComboBox<String> combo = new JComboBox<>(new String[]{"Java", "Python", "C++"});
JPasswordField password = new JPasswordField(20);

// FlowLayout — left to right, wrapping
frame.setLayout(new FlowLayout());

// BorderLayout — 5 regions: NORTH, SOUTH, EAST, WEST, CENTER
frame.setLayout(new BorderLayout());
frame.add(new JButton("North"), BorderLayout.NORTH);
frame.add(new JButton("Center"), BorderLayout.CENTER);

// GridLayout — rows × columns grid
frame.setLayout(new GridLayout(3, 2)); // 3 rows, 2 cols

JButton button = new JButton("Click Me!");

// Method 1: ActionListener with lambda
button.addActionListener(e -> {
    JOptionPane.showMessageDialog(null, "Button was clicked!");
});

// Method 2: Implementing ActionListener
button.addActionListener(new ActionListener() {
    @Override
    public void actionPerformed(ActionEvent e) {
        System.out.println("Clicked!");
    }
});

// Message dialog
JOptionPane.showMessageDialog(null, "Welcome to Java!");

// Input dialog
String name = JOptionPane.showInputDialog("Enter your name:");

// Confirm dialog
int choice = JOptionPane.showConfirmDialog(null, "Are you sure?");

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

public class CalculatorGUI {
    public static void main(String[] args) {
        JFrame frame = new JFrame("Java Calculator");
        frame.setSize(300, 400);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLayout(new BorderLayout());

        JTextField display = new JTextField();
        display.setFont(new Font("Arial", Font.BOLD, 24));
        display.setEditable(false);
        frame.add(display, BorderLayout.NORTH);

        JPanel panel = new JPanel(new GridLayout(4, 4, 5, 5));
        String[] buttons = {
            "7", "8", "9", "/",
            "4", "5", "6", "*",
            "1", "2", "3", "-",
            "0", "C", "=", "+"
        };

        StringBuilder input = new StringBuilder();

        for (String text : buttons) {
            JButton btn = new JButton(text);
            btn.setFont(new Font("Arial", Font.BOLD, 18));
            btn.addActionListener(e -> {
                String cmd = e.getActionCommand();
                if (cmd.equals("C")) {
                    input.setLength(0);
                    display.setText("");
                } else if (cmd.equals("=")) {
                    try {
                        // Simple evaluation (production apps use a parser)
                        display.setText("Result");
                    } catch (Exception ex) {
                        display.setText("Error");
                    }
                } else {
                    input.append(cmd);
                    display.setText(input.toString());
                }
            });
            panel.add(btn);
        }

        frame.add(panel, BorderLayout.CENTER);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }
}