我是自己純手工用Java編寫的計算器

//filename:JiShuan
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Image;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JTextField;
import java.awt.BorderLayout;
import javax.swing.JPanel;
import java.awt.GridLayout;
import javax.swing.SwingConstants;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.Toolkit;

public class JiShuan {

	private JFrame frame;
	private JTextField textShow;
	private JButton[] btn = {new JButton("1"),new JButton("2"),new JButton("3"),new JButton("+"),
							new JButton("4"),new JButton("5"),new JButton("6"),new JButton("-"),
							new JButton("7"),new JButton("8"),new JButton("9"),new JButton("*"),
							new JButton("0"),new JButton("."),new JButton("="),new JButton("/")};
	/**
	 * Launch the application.
	 */
	public static void main(String[] args) {
		EventQueue.invokeLater(new Runnable() {
			public void run() {
				try {
					JiShuan window = new JiShuan();
					window.frame.setVisible(true);
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		});
	}

	/**
	 * Create the application.
	 */
	public JiShuan() {
		initialize();
	}

	/**
	 * Initialize the contents of the frame.
	 */
	private MyButtonActionListener listener = new MyButtonActionListener();
	private void initialize() {
		frame = new JFrame();
		frame.setIconImage(Toolkit.getDefaultToolkit().getImage(JiShuan.class.getResource("/image/1.jpg")));
		//Image imageIcon = new ImageIcon(getClass().getClassLoader.getResource(imagePath)).getImage();
		//Image image=new ImageIcon(Toolkit.getDefaultToolkit().getImage(JiShuan.class.getResource("/Images/Desert.jpg"))).getImage();
	//	frame.setIconImage(imageIcon);
		//frame.setIconImage(Toolkit.getDefaultToolkit().getImage(JiShuan.class.getResource("/Image/1.jpg")));
		frame.setTitle("\u8BA1\u7B97\u5668");
		frame.setBounds(100, 120, 242, 323);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.getContentPane().setLayout(null);
		
		textShow = new JTextField();
		textShow.setFont(new Font("宋體", Font.PLAIN, 40));
		textShow.setText("0");
		textShow.setBounds(10, 10, 205, 55);
		frame.getContentPane().add(textShow);
		textShow.setColumns(10);
		textShow.setBackground(Color.LIGHT_GRAY);   //設定文字框顏色
		textShow.setHorizontalAlignment(SwingConstants.RIGHT);//設定文字的內容右對齊
		
		JPanel panel = new JPanel();
		panel.setBounds(10, 75, 205, 197);
		frame.getContentPane().add(panel);
		panel.setLayout(new GridLayout(4, 4, 0, 0));
		
		for(int i=0;i<16;i++){
			btn[i].addActionListener(listener);
			panel.add(btn[i]);
		}
	}
	String str="";
	double num,sum=0.0;
	char last;
	int f=1;
	class MyButtonActionListener implements ActionListener{

		public void actionPerformed(ActionEvent e) {
			JButton button = (JButton)e.getSource();
			char sign = button.getText().charAt(0);
			switch(sign){
				case '0':str = str+"0";textShow.setText(str);break;
				case '1':str = str+"1";textShow.setText(str);break;
				case '2':str = str+"2";textShow.setText(str);break;
				case '3':str = str+"3";textShow.setText(str);break;
				case '4':str = str+"4";textShow.setText(str);break;
				case '5':str = str+"5";textShow.setText(str);break;
				case '6':str = str+"6";textShow.setText(str);break;
				case '7':str = str+"7";textShow.setText(str);break;
				case '8':str = str+"8";textShow.setText(str);break;
				case '9':str = str+"9";textShow.setText(str);break;
				case '+':
					textShow.setText("");
					last='+';
					if(f!=0){
						f=0;
						sum=Double.parseDouble(str);
					}	
					else
						sum=sum+Double.parseDouble(str);
					textShow.setText(sum+"");
					str="";
					break;
				case '-':
					textShow.setText("");
					last='-';
					if(f!=0){
						f=0;
						sum=Double.parseDouble(str);
					}	
					else
						sum=sum-Double.parseDouble(str);
					textShow.setText(sum+"");
					str="";
					break;
				case '*':
					textShow.setText("");
					last='*';
					if(f!=0){
						f=0;
						sum=Double.parseDouble(str);
					}	
					else
						sum=sum*Double.parseDouble(str);
					textShow.setText(sum+"");
					str="";
					break;
				case '/':
					textShow.setText("");
					last='/';
					if(f!=0){
						f=0;
						sum=Double.parseDouble(str);
					}	
					else
						sum=sum/Double.parseDouble(str);
					textShow.setText(sum+"");
					str="";
					break;
				case '=':
					switch(last)
					{
						case '+':sum=sum+Double.parseDouble(str);str="";break;
						case '-':sum=sum-Double.parseDouble(str);str="";break;
						case '*':sum=sum*Double.parseDouble(str);str="";break;
						case '/':sum=sum/Double.parseDouble(str);str="";break;
					}
					textShow.setText(sum+"");
					break;
			}
		}
		
	}
	
	private Color Color(int i, int j, int k) {
		// TODO 自動生成的方法存根
		return null;
	}
}