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

public class MyCalc extends JFrame {
	private JButton display;
	private double result;
	private String lastCom;
	private boolean start;

	private void addButton(String name, ActionListener listener, int x, int y,
			int width, int height) {
		JButton button = new JButton(name);
		button.setBounds(x, y, width, height);
		button.addActionListener(listener);
		getContentPane().add(button);
	}

	public MyCalc() {
		getContentPane().setLayout(null);
		setTitle("Мой калькулятор");
		setBounds(200, 200, 203, 242);
		getContentPane().setBackground(new Color(100, 149, 237));

		ActionListener output = new OutputAction();
		ActionListener command = new CommandAction();

		result = 0;
		lastCom = "=";
		start = true;

		display = new JButton("0");
		display.setEnabled(false);
		getContentPane().add(display);
		display.setBounds(5, 10, 177, 30);

		addButton("7", output, 5, 50, 41, 20);
		addButton("8", output, 50, 50, 41, 20);
		addButton("9", output, 95, 50, 41, 20);
		addButton("/", command, 140, 50, 41, 20);
		

		addButton("4", output, 5, 75, 41, 20);
		addButton("5", output, 50, 75, 41, 20);
		addButton("6", output, 95, 75, 41, 20);
		addButton("*", command, 140, 75, 41, 20);
		

		addButton("1", output, 5, 100, 41, 20);
		addButton("2", output, 50, 100, 41, 20);
		addButton("3", output, 95, 100, 41, 20);
		addButton("-", command, 140, 100, 41, 20);
		

		addButton("0", output, 5, 125, 41, 20);
		addButton(".", output, 50, 125, 41, 20);
		addButton("=", command, 95, 125, 41, 20);
		addButton("+", command, 140, 125, 41, 20);
		
		addButton("с", command, 5, 150, 85, 20);
		addButton("<", command, 95, 150, 85, 20);
		
		addButton("sqrt", command, 5, 175, 85, 20);
		addButton("pow(x,2)", command, 95, 175, 85, 20);
		
		setDefaultCloseOperation(EXIT_ON_CLOSE);
		setVisible(true);
		TextEvent t = new TextEvent(getContentPane(), 1);
	}

	private class OutputAction implements ActionListener {
		public void actionPerformed(ActionEvent event) {
			String input = event.getActionCommand();
			if (start) {
				display.setText("");
				start = false;
			}
			display.setText(display.getText() + input);
		}
	}

	private class CommandAction implements ActionListener {
		public void actionPerformed(ActionEvent event) {
			String command = event.getActionCommand();
			if (start) {
				if (command.equals("-")) {
					display.setText(command);
					start = false;
				} else {
					lastCom = command;
				}
			}else if (command.equals("sqrt")) {
				display.setText("" + Math.sqrt(Double.parseDouble(display.getText())));
				start = true;
			} else if (command.equals("pow(x,2)")) {
				display.setText("" + Math.pow(Double.parseDouble(display.getText()), 2));
				start = true;
			}else if (command.equals("с")) {
				display.setText("");
				start = true;
			}else if (command.equals("<")) {
				//???
			} else {
				calculate(Double.parseDouble(display.getText()));
				lastCom = command;
				start = true;
			}
		}
	}

	public void calculate(double x) {
		if (lastCom.equals("+")) {
			result += x;
			display.setText("" + result);
		} else if (lastCom.equals("-")) {
			result -= x;
			display.setText("" + result);
		} else if (lastCom.equals("*")) {
			result *= x;
			display.setText("" + result);
		} else if (lastCom.equals("/")) {
			if (x == 0) {
				display.setText("Деление на ноль");
			} else {
				result /= x;
				display.setText("" + result);
			}
		} else if (lastCom.equals("=")) {
			result = x;
			display.setText("" + result);
		}
	}
	public static void main(String[] args) {
		new MyCalc();
	}
}