java設計一個計算器

本文是對上一個簡單的計算器的優化和改進。
效果如圖


代碼如下：

import java.awt.AWTException;
import java.awt.BorderLayout;
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JTextField;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.math.BigDecimal;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Timer;
import java.util.TimerTask;
import java.awt.event.ActionEvent;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Robot;
import java.awt.SystemColor;

import javax.swing.SwingConstants;
import java.awt.Color;
import javax.swing.JLabel;

public class Calculator extends JFrame {

	private JPanel contentPane;
	private JTextField result;
	private int operator = 0;
	String num1 = "", num2 = "";
	private double number1, number2;
	private boolean flag = false;
	double value;
	private JTextField showNumber;
	double m1, m2, m3;
	int pointNumber = 0;
	private JTextField time;
	private JTextField texttime;
	
	public void count() {
		if (operator != 0) {
			number1 = Double.parseDouble(num1);
			number2 = Double.parseDouble(result.getText());
			if (operator == 1) {
				BigDecimal p1 = new BigDecimal(num1);
				BigDecimal p2 = new BigDecimal(result.getText());
				value = p1.add(p2).doubleValue();
			} else if (operator == 2) {
				BigDecimal p1 = new BigDecimal(num1);
				BigDecimal p2 = new BigDecimal(result.getText());
				value = p1.subtract(p2).doubleValue();
			} else if (operator == 3) {
				BigDecimal p1 = new BigDecimal(num1);
				BigDecimal p2 = new BigDecimal(result.getText());
				value = p1.multiply(p2).doubleValue();
			} else if (operator == 4) {
				BigDecimal p1 = new BigDecimal(num1);
				BigDecimal p2 = new BigDecimal(result.getText());
				value = p1.divide(p2).doubleValue();
			}
			if ((int) value == value) {
				int exp1 = (int) value;
				result.setText(exp1 + "");
			} else {
				String exp0 = String.valueOf(value);
				result.setText(exp0);
			}
		}
	}
	
public void number(ActionEvent e)
	{
		if (showNumber.getText().equals("0")) {
			showNumber.setText(e.getActionCommand());
		} else
			showNumber.setText(showNumber.getText() + e.getActionCommand());
		if (flag) {
			result.setText(e.getActionCommand());
			flag = false;
		} else {
			if (result.getText().equals("0"))
				result.setText(e.getActionCommand());
			else
				result.setText(result.getText() + e.getActionCommand());
		}
	}
	
	/**
	 * Launch the application.
	 */
	public static void main(String[] args) {
		EventQueue.invokeLater(new Runnable() {
			public void run() {
				try {
					Calculator frame = new Calculator();
					frame.setVisible(true);
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		});
	}

	/**
	 * Create the frame.
	 */

	public Calculator() {
		setTitle("\u8BA1\u7B97\u5668");
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setBounds(100, 100, 318, 435);
		contentPane = new JPanel();
		contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
		setContentPane(contentPane);
		contentPane.setBackground(SystemColor.menu);
		contentPane.setLayout(null);

		result = new JTextField();
		result.setFont(new Font("宋體", Font.BOLD, 20));
		result.setText("0");
		result.setHorizontalAlignment(SwingConstants.RIGHT);
		result.setBounds(10, 99, 284, 34);
		contentPane.add(result);
		result.setColumns(10);

		showNumber = new JTextField();
		showNumber.setHorizontalAlignment(SwingConstants.RIGHT);
		showNumber.setFont(new Font("宋體", Font.BOLD, 20));
		showNumber.setText("0");
		showNumber.setBounds(10, 67, 284, 34);
		contentPane.add(showNumber);
		showNumber.setColumns(10);

//數字部分

		JButton btn0 = new JButton("0");
		btn0.setBackground(Color.WHITE);
		btn0.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				if (showNumber.getText().equals("0")) {

				} else
					showNumber.setText(showNumber.getText() + "0");
				if (flag) {
					result.setText("0");
					flag = false;
				} else {

					if (result.getText().equals("0")) {
						result.setText("0");
					} else
						result.setText(result.getText() + 0);

				}
			}
		});
		btn0.setFont(new Font("黑體", Font.BOLD, 15));
		btn0.setBounds(39, 266, 53, 43);
		contentPane.add(btn0);

		JButton btn1 = new JButton("1");
		btn1.setBackground(Color.WHITE);
		btn1.setFont(new Font("黑體", Font.BOLD, 15));
		btn1.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				number(e);
			}
		});
		btn1.setBounds(39, 143, 53, 43);
		contentPane.add(btn1);

		JButton btn2 = new JButton("2");
		btn2.setBackground(Color.WHITE);
		btn2.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				number(e);
			}
		});
		btn2.setFont(new Font("黑體", Font.BOLD, 15));
		btn2.setBounds(90, 143, 53, 43);
		contentPane.add(btn2);

		JButton btn3 = new JButton("3");
		btn3.setBackground(Color.WHITE);
		btn3.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				number(e);
			}
		});
		btn3.setFont(new Font("黑體", Font.BOLD, 15));
		btn3.setBounds(141, 143, 53, 43);
		contentPane.add(btn3);

		JButton btn4 = new JButton("4");
		btn4.setBackground(Color.WHITE);
		btn4.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				number(e);
			}
		});
		btn4.setFont(new Font("黑體", Font.BOLD, 15));
		btn4.setBounds(39, 184, 53, 43);
		contentPane.add(btn4);

		JButton btn5 = new JButton("5");
		btn5.setBackground(Color.WHITE);
		btn5.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				number(e);
			}
		});
		btn5.setFont(new Font("黑體", Font.BOLD, 15));
		btn5.setBounds(90, 184, 53, 43);
		contentPane.add(btn5);

		JButton btn6 = new JButton("6");
		btn6.setBackground(Color.WHITE);
		btn6.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				number(e);
			}
		});
		btn6.setFont(new Font("黑體", Font.BOLD, 15));
		btn6.setBounds(141, 184, 53, 43);
		contentPane.add(btn6);

		JButton btn7 = new JButton("7");
		btn7.setBackground(new Color(255, 255, 255));
		btn7.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				number(e);
			}
		});
		btn7.setFont(new Font("黑體", Font.BOLD, 15));
		btn7.setBounds(39, 225, 53, 43);
		contentPane.add(btn7);

		JButton btn8 = new JButton("8");
		btn8.setBackground(Color.WHITE);
		btn8.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				number(e);
			}
		});
		btn8.setFont(new Font("黑體", Font.BOLD, 15));
		btn8.setBounds(90, 225, 53, 43);
		contentPane.add(btn8);

		JButton btn9 = new JButton("9");
		btn9.setBackground(Color.WHITE);
		btn9.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				number(e);
			}
		});
		btn9.setFont(new Font("黑體", Font.BOLD, 15));
		btn9.setBounds(141, 225, 53, 43);
		contentPane.add(btn9);

		// 運算符
		JButton btnAdd = new JButton("+");
		btnAdd.setBackground(Color.WHITE);
		btnAdd.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				count();
				if (showNumber.getText().equals("0")) {
					showNumber.setText("0");
				} else
					showNumber.setText(showNumber.getText() + "+");
				num1 = result.getText();
				operator = 1;
				flag = true;
				pointNumber = 0;
			}
		});
		btnAdd.setFont(new Font("黑體", Font.BOLD, 15));
		btnAdd.setBounds(192, 143, 53, 43);
		contentPane.add(btnAdd);

		JButton btnsubtract = new JButton("-");
		btnsubtract.setBackground(Color.WHITE);
		btnsubtract.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				count();
				if (showNumber.getText().equals("0")) {
					showNumber.setText("-");
					result.setText("-");
				} else
					showNumber.setText(showNumber.getText() + "-");
				num1 = result.getText();
				operator = 2;
				flag = true;
				pointNumber = 0;
			}
		});
		btnsubtract.setFont(new Font("黑體", Font.BOLD, 15));
		btnsubtract.setBounds(192, 184, 53, 43);
		contentPane.add(btnsubtract);

		JButton btnmultiply = new JButton("*");
		btnmultiply.setBackground(Color.WHITE);
		btnmultiply.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				count();
				if (showNumber.getText().equals("0")) {
					showNumber.setText("0");
				} else
					showNumber.setText(showNumber.getText() + "*");
				num1 = result.getText();
				operator = 3;
				flag = true;
				pointNumber = 0;

			}
		});
		btnmultiply.setFont(new Font("黑體", Font.BOLD, 15));
		btnmultiply.setBounds(192, 225, 53, 43);
		contentPane.add(btnmultiply);

		JButton btndivide = new JButton("/");
		btndivide.setBackground(Color.WHITE);
		btndivide.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				count();
				if (showNumber.getText().equals("0")) {
					showNumber.setText("0");
				} else
					showNumber.setText(showNumber.getText() + "/");
				num1 = result.getText();
				operator = 4;
				flag = true;
				pointNumber = 0;
			}
		});
		btndivide.setFont(new Font("黑體", Font.BOLD, 15));
		btndivide.setBounds(192, 266, 53, 43);
		contentPane.add(btndivide);

		// 符號部分
		JButton btnpoint = new JButton(".");
		btnpoint.setBackground(Color.WHITE);
		btnpoint.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				if (showNumber.getText().equals("0")) {
					showNumber.setText("0.");
				} else

					showNumber.setText(showNumber.getText() + ".");
				if (flag) {
					result.setText(".");
					pointNumber++;
					flag = false;
				} else {
					if (result.getText().equals("0")) {
						result.setText("0.");
						pointNumber++;
					} else {
						result.setText(result.getText() + ".");
						pointNumber++;
					}
				}

				flag = false;
				if (pointNumber > 1) {
					new JOptionPane();
					JOptionPane.showMessageDialog(null, "一個數不能有多個小數點");
				}
			}

		});
		btnpoint.setFont(new Font("黑體", Font.BOLD, 15));
		btnpoint.setBounds(141, 266, 53, 43);
		contentPane.add(btnpoint);

		JButton btnC = new JButton("C");
		btnC.setBackground(Color.WHITE);
		btnC.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				showNumber.setText("0");
				result.setText("0");
				number1 = 0;
				number2 = 0;
				value = 0;
				operator = 0;
				pointNumber = 0;
			}
		});
		btnC.setFont(new Font("黑體", Font.BOLD, 15));
		btnC.setBounds(90, 266, 53, 43);
		contentPane.add(btnC);

		JButton btnequal = new JButton("=");
		btnequal.setBackground(SystemColor.activeCaption);
		btnequal.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				showNumber.setText(showNumber.getText() + "=");
				// num1 operator num2 =
				number1 = Double.parseDouble(num1);
				number2 = Double.parseDouble(result.getText());
				if (operator == 1) {
					BigDecimal p1 = new BigDecimal(num1);
					BigDecimal p2 = new BigDecimal(result.getText());
					value = p1.add(p2).doubleValue();
				} else if (operator == 2) {
					BigDecimal p1 = new BigDecimal(num1);
					BigDecimal p2 = new BigDecimal(result.getText());
					value = p1.subtract(p2).doubleValue();
				} else if (operator == 3) {
					BigDecimal p1 = new BigDecimal(num1);
					BigDecimal p2 = new BigDecimal(result.getText());
					value = p1.multiply(p2).doubleValue();
				} else if (operator == 4) {
					value = number1 / number2;
					if (number2 == 0) {
						new JOptionPane();
						JOptionPane.showMessageDialog(null, "除數不能爲0！");
					}
				}
				if ((int) value == value) {
					int exp1 = (int) value;
					result.setText(exp1 + "");
				} else {
					String exp0 = String.valueOf(value);
					result.setText(exp0);
				}
				operator = 0;
			}
		});
		btnequal.setFont(new Font("黑體", Font.PLAIN, 37));
		btnequal.setBounds(39, 307, 207, 43);
		contentPane.add(btnequal);
		 
		JLabel lblNewLabel = new JLabel("\u7528\u6765\u8BA1\u7B97\u591A\u9879\u5F0F\u8FD0\u7B97");
		lblNewLabel.setHorizontalAlignment(SwingConstants.RIGHT);
		lblNewLabel.setForeground(Color.LIGHT_GRAY);
		lblNewLabel.setBounds(164, 10, 130, 24);
		contentPane.add(lblNewLabel);
		
		JLabel lblNewLabel_1 = new JLabel("\u4E0D\u8003\u8651\u4F18\u5148\u7EA7");
		lblNewLabel_1.setHorizontalAlignment(SwingConstants.RIGHT);
		lblNewLabel_1.setForeground(Color.LIGHT_GRAY);
		lblNewLabel_1.setBounds(152, 29, 142, 24);
		contentPane.add(lblNewLabel_1);
		
		texttime = new JTextField();
		texttime.setHorizontalAlignment(SwingConstants.RIGHT);
		texttime.setBounds(10, 12, 153, 24);
		contentPane.add(texttime);
		texttime.setColumns(10);
			
		 Timer timer=new Timer();
		 timer.schedule(new TimerTask() {

			@Override
			public void run() {
				SimpleDateFormat time = new SimpleDateFormat("yyyy年MM月dd日 HH:mm:ss");
				texttime.setText(time.format(new Date()));
			}
			 
		 }, 0, 1000);	 
		
	}
}

相比之前的簡單計算器這個可以進行一些簡單的多項式運算，並且用count（）和number（）方法相比之前大大減少了重複代碼量。最後爲了豐富頁面添加了一個顯示時間的文本框。
這個計算器仍存在不好的地方後面有時間會繼續改進。