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lesson2/Calculator.java

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2.9 KiB

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
public class Calculator extends JFrame implements ActionListener {
private JTextField display;
private StringBuilder input;
public Calculator() {
input = new StringBuilder();
display = new JTextField();
display.setEditable(false);
display.setFont(new Font("Arial", Font.BOLD, 32));
display.setHorizontalAlignment(JTextField.RIGHT);
display.setBackground(Color.LIGHT_GRAY);
JPanel panel = new JPanel();
panel.setLayout(new GridLayout(5, 4, 10, 10)); // Increase number of rows
panel.setBackground(Color.GRAY);
String[] buttons = {
"7", "8", "9", "/",
"4", "5", "6", "*",
"1", "2", "3", "-",
"C", "0", ".", "+", // Add decimal point
"<-", "=", "" // Add delete button
};
for (String text : buttons) {
JButton button = new JButton(text);
button.setFont(new Font("Arial", Font.PLAIN, 24));
button.addActionListener(this);
button.setBackground(Color.WHITE);
panel.add(button);
}
add(display, BorderLayout.NORTH);
add(panel, BorderLayout.CENTER);
setTitle("Calculator");
setSize(400, 500);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLocationRelativeTo(null);
}
public void actionPerformed(ActionEvent e) {
String command = e.getActionCommand();
if (command.charAt(0) == 'C') {
input.setLength(0);
display.setText("");
} else if (command.equals("<-")) { // Delete the last character
if (input.length() > 0) {
input.setLength(input.length() - 1);
display.setText(input.toString());
}
} else if (command.charAt(0) == '=') {
try {
double result = evaluate(input.toString());
display.setText(String.valueOf(result));
input.setLength(0);
} catch (ScriptException ex) {
display.setText("Error");
input.setLength(0);
}
} else {
input.append(command);
display.setText(input.toString());
}
}
private double evaluate(String expression) throws ScriptException {
ScriptEngine engine = new ScriptEngineManager().getEngineByName("JavaScript");
return ((Number) engine.eval(expression)).doubleValue();
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
Calculator calculator = new Calculator();
calculator.setVisible(true);
});
}
}