import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class calculator extends JFrame implements ActionListener {
    JTextField t1 = new JTextField(20);
    String oper = "";
    int first = 0, second = 0, result = 0;
    public calculator() {
        String[] buttons = {"7", "8", "9", "/", "4", "5", "6", "*", "1", "2", "3", "-", "0", "=", "+", "%"};
        JPanel panel = new JPanel(new GridLayout(4, 4));
        for (String text : buttons) {
            JButton button = new JButton(text);
            button.addActionListener(this);
            panel.add(button);
        }
        JButton space = new JButton("C");
        space.addActionListener(this);
        setLayout(new BorderLayout());
        add(t1, BorderLayout.NORTH);
        add(panel, BorderLayout.CENTER);
        add(space, BorderLayout.SOUTH);
        setTitle("Calculator");
        setSize(250, 300);
        setVisible(true);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
    public void actionPerformed(ActionEvent ae) {
        String a = ae.getActionCommand();
        if ("0123456789".contains(a)) {
            t1.setText(t1.getText() + a);
        } else if ("+-*/%".contains(a)) {
            first = Integer.parseInt(t1.getText());
            oper = a;
            t1.setText("");
        } else if (a.equals("=")) {
            second = Integer.parseInt(t1.getText());
            switch (oper) {
                case "+": result = first + second; break;
                case "-": result = first - second; break;
                case "*": result = first * second; break;
                case "/": result = first / second; break;
                case "%": result = first % second; break;
            }
            t1.setText(String.valueOf(result));
        } else if (a.equals("C")) {
            t1.setText("");
        }
    }
    public static void main(String[] args) {
        new calculator();
    }
}