issue50.txt

ISSUE.NO.50 #Android 
by tejal hajari

MINI CALCULATOR

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

public class Calculator {
    private static JTextField inputField;

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
            createAndShowGUI();
        });
    }

    private static void createAndShowGUI() {
        JFrame frame = new JFrame("Calculator");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(300, 400);
        frame.setLayout(new BorderLayout());

        inputField = new JTextField();
        inputField.setHorizontalAlignment(JTextField.RIGHT);
        frame.add(inputField, BorderLayout.NORTH);

        JPanel buttonPanel = new JPanel();
        buttonPanel.setLayout(new GridLayout(4, 4));

        String[] buttonLabels = {
            "7", "8", "9", "/",
            "4", "5", "6", "*",
            "1", "2", "3", "-",
            "0", "C", "=", "+"
        };

        for (String label : buttonLabels) {
            JButton button = new JButton(label);
            button.addActionListener(new ButtonClickListener());
            buttonPanel.add(button);
        }

        frame.add(buttonPanel, BorderLayout.CENTER);

        frame.setVisible(true);
    }

    private static class ButtonClickListener implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            JButton source = (JButton) e.getSource();
            String buttonText = source.getText();

            switch (buttonText) {
                case "C":
                    inputField.setText("");
                    break;
                case "=":
                    try {
                        String expression = inputField.getText();
                        double result = evaluateExpression(expression);
                        inputField.setText(String.valueOf(result));
                    } catch (Exception ex) {
                        inputField.setText("Error");
                    }
                    break;
                default:
                    inputField.setText(inputField.getText() + buttonText);
                    break;
            }
        }

        private double evaluateExpression(String expression) {
            // Implement your expression evaluation logic here
            // For simplicity, you can use JavaScript engine or other libraries for this purpose
            // Example using JavaScript engine: https://stackoverflow.com/a/34226791
            return 0; // Placeholder return value
        }
    }
}