JAVA 계산기 프로그램 부분완성

package com.tansanc.tistory;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import javax.swing.JButton;

import javax.swing.JFrame;

import javax.swing.JPanel;

import javax.swing.JTextField;

class Cal extends JFrame
{

	private JTextField t1;

	private JButton b1, b2, b3, b4, b5, b6, b7, b8, b9, b0;

	JButton pl, mi, mu, di, cal, c;

	String x, y;

	public Cal()
	{

		setSize(285, 350);

		setDefaultCloseOperation(EXIT_ON_CLOSE);

		setTitle("Calculator");

		JPanel p = new JPanel();

		p.setLayout(null);

		t1 = new JTextField(10);

		p.add(t1);

		b1 = new JButton("1");

		p.add(b1);

		b1.addActionListener(new Number());

		b2 = new JButton("2");

		p.add(b2);

		b2.addActionListener(new Number());

		b3 = new JButton("3");

		p.add(b3);

		b3.addActionListener(new Number());

		b4 = new JButton("4");

		p.add(b4);

		b4.addActionListener(new Number());

		b5 = new JButton("5");

		p.add(b5);

		b5.addActionListener(new Number());

		b6 = new JButton("6");

		p.add(b6);

		b6.addActionListener(new Number());

		b7 = new JButton("7");

		p.add(b7);

		b7.addActionListener(new Number());

		b8 = new JButton("8");

		p.add(b8);

		b8.addActionListener(new Number());

		b9 = new JButton("9");

		p.add(b9);

		b9.addActionListener(new Number());

		b0 = new JButton("0");

		p.add(b0);

		b0.addActionListener(new Number());

		pl = new JButton("+");

		p.add(pl);

		pl.addActionListener(new Number());

		mi = new JButton("-");

		p.add(mi);

		mi.addActionListener(new Number());

		mu = new JButton("*");

		p.add(mu);

		mu.addActionListener(new Number());

		di = new JButton("/");

		p.add(di);

		di.addActionListener(new Number());

		cal = new JButton("=");

		p.add(cal);

		cal.addActionListener(new Number());

		c = new JButton("C");

		p.add(c);

		c.addActionListener(new Number());

		t1.setBounds(10, 10, 245, 80);

		b1.setBounds(10, 105, 45, 45);

		b2.setBounds(60, 105, 45, 45);

		b3.setBounds(110, 105, 45, 45);

		b4.setBounds(10, 155, 45, 45);

		b5.setBounds(60, 155, 45, 45);

		b6.setBounds(110, 155, 45, 45);

		b7.setBounds(10, 205, 45, 45);

		b8.setBounds(60, 205, 45, 45);

		b9.setBounds(110, 205, 45, 45);

		b0.setBounds(60, 255, 45, 45);

		pl.setBounds(160, 105, 45, 45);

		mi.setBounds(160, 155, 45, 45);

		mu.setBounds(160, 205, 45, 45);

		di.setBounds(160, 255, 45, 45);

		c.setBounds(110, 255, 45, 45);

		cal.setBounds(210, 105, 45, 195);

		add(p);

		setVisible(true);

	}

	String operand1;
	String operator;
	private class Number implements ActionListener
	{

		public void actionPerformed(ActionEvent e)
		{
			if( e.getSource() == b1)
			{
				t1.setText(t1.getText() + "1");
			}
			else if( e.getSource() == b2)
			{
				t1.setText(t1.getText() + "2");
			}
			else if( e.getSource() == pl)
			{
				operand1 = t1.getText();
				operator = "+";
				t1.setText("");
			}
			else if( e.getSource() == cal)
			{
				if(operator == "+")
				{
					t1.setText("" + ( Integer.parseInt(operand1) + Integer.parseInt(t1.getText())) );
				}
			}
		}
	}

}

public class CardTest
{

	public static void main(String[] args)
	{

		Cal Cals = new Cal();

	}

}