import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class Calculator extends JFrame {
	// 顯示計(jì)算器按鈕的值和計(jì)算后的值
	JTextField display;
	JPanel panel1;// 面板1，放文本框
	JPanel panel2;// 面板2，放按鈕
	String nowButton;// 當(dāng)前按下的變量

	public Calculator() {
		this.setBounds(0, 0, 500, 500);
		this.setLocationRelativeTo(null);// 讓窗口在屏幕中間顯示
		setTitle("計(jì)算器");

		// 菜單欄
		JMenuBar menuBar = new JMenuBar();// 創(chuàng)建一個(gè)菜單欄
		JMenu editMenu = new JMenu("編輯(E)");// 創(chuàng)建一級(jí)菜單

		//創(chuàng)建 "編輯" 一級(jí)菜單的子菜單
		JMenuItem copyMenuItem = new JMenuItem("復(fù)制");
		JMenuItem pasteMenuItem = new JMenuItem("粘貼");
		
		// 子菜單添加到一級(jí)菜單
		editMenu.add(copyMenuItem);
		editMenu.add(pasteMenuItem);
		
		//將一級(jí)菜單添加到菜單欄
		menuBar.add(editMenu);
		//將菜單欄添加到JFrame窗口
		this.setJMenuBar(menuBar);
		
		// 設(shè)置 "復(fù)制" 子菜單被點(diǎn)擊的監(jiān)聽(tīng)器
		copyMenuItem.addActionListener(new ActionListener() {
			@Override
			public void actionPerformed(ActionEvent e) {
				System.out.println("復(fù)制  被點(diǎn)擊");
				String i = display.getText();
				display.copy();

				JButton jb1 = new JButton("復(fù)制");
				jb1.addActionListener(this);
			}
		});
		// 設(shè)置 "粘貼" 子菜單被點(diǎn)擊的監(jiān)聽(tīng)器
		pasteMenuItem.addActionListener(new ActionListener() {
			@Override
			public void actionPerformed(ActionEvent e) {
				System.out.println("粘貼  被點(diǎn)擊");
				display.paste();
			}
		});

		// 初始化，把文本框加在上面north里
		display = new JTextField("");
		display.setEnabled(true);
		add(display, BorderLayout.NORTH);

		// 監(jiān)聽(tīng)操作按鈕
		ActionListener command = new commandAction();

		// panel1是中間16個(gè)按鈕的布局，放到布局管理器的center里
		panel1 = new JPanel();
		panel1.setLayout(new GridLayout(5, 4, 5, 5));

		addButton1("7", command);
		addButton1("8", command);
		addButton1("9", command);
		addButton1("/", command);
		addButton1("4", command);
		addButton1("5", command);
		addButton1("6", command);
		addButton1("*", command);
		addButton1("1", command);
		addButton1("2", command);
		addButton1("3", command);
		addButton1("-", command);
		addButton1("0", command);
		addButton1("+/-", command);
		addButton1(".", command);
		addButton1("+", command);
		addButton1("1/x", command);
		addButton1("%", command);
		addButton1("sqrt", command);
		addButton1("=", command);

		add(panel1, BorderLayout.SOUTH);

		// panel2是下面的backspace和c的2個(gè)的布局，放到布局管理器的south里
		panel2 = new JPanel();
		panel2.setLayout(new GridLayout(1, 2, 5, 5));

		addButton2("BackSace", command);
		addButton2("C", command);

		add(panel2, BorderLayout.CENTER);

		pack(); // 根據(jù)組件大小自動(dòng)調(diào)節(jié)窗口大小
	}

	// 注冊(cè)事件監(jiān)聽(tīng)器方法（panel1的）
	public void addButton1(String label, ActionListener listener) {
		// TODO 自動(dòng)生成的方法存根
		JButton button = new JButton(label);
		button.addActionListener(listener);
		panel1.add(button);
	}

	// 注冊(cè)監(jiān)聽(tīng)器方法（panel2的）
	private void addButton2(String label, ActionListener listener) {
		// TODO 自動(dòng)生成的方法存根
		JButton button = new JButton(label);
		button.addActionListener(listener);
		panel2.add(button);
	}

	// 創(chuàng)建內(nèi)部類，作用于單擊按鈕執(zhí)行命令的監(jiān)聽(tīng)器
	class commandAction implements ActionListener {
		@Override
		public void actionPerformed(ActionEvent event) {
			// TODO 自動(dòng)生成的方法存根
			nowButton = event.getActionCommand();

			if (nowButton != "BackSace" && nowButton != "=") {
				// 如果是回退和=就不打印這個(gè)了
				display.setText(display.getText() + nowButton);
			}

			if (nowButton.equals("=")) {
				// 如果是等于號(hào)，就計(jì)算結(jié)果
				display.setText(jisuan1(display.getText()));
			}

			if (nowButton.equals("BackSace")) {
				// 回退一個(gè)字符
				StringBuffer sb = new StringBuffer(display.getText());
				display.setText(sb.substring(0, sb.length() - 1));
			}
			if (nowButton.equals("C")) {
				// 清空
				display.setText("");
			}
		}
	}

	// 用來(lái)計(jì)算的方法
	public String jisuan1(String string) {
		StringBuffer sb = new StringBuffer(string);
		int commandCount = 0;// 符號(hào)數(shù)量

		int j = 0;// 計(jì)數(shù)器
		// 計(jì)算有多少個(gè)運(yùn)算符，就有n+1個(gè)數(shù)字
		for (j = 0; j < sb.length(); j++) {
			if (sb.charAt(j) <= '9' && sb.charAt(j) >= '0' || sb.charAt(j) == '.') {
				continue;
			} else {
				commandCount++;
			}
		}

		// 初始化符號(hào)數(shù)組
		char[] command = new char[commandCount];
		// 初始化數(shù)字?jǐn)?shù)組（用字符串表示）
		String[] num = new String[commandCount + 1];
		for (j = 0; j < num.length; j++) {
			num[j] = "";
		}

		// 遍歷一遍，吧每個(gè)數(shù)字存進(jìn)數(shù)字?jǐn)?shù)組，每個(gè)符號(hào)存進(jìn)符號(hào)數(shù)組
		int k = 0;
		for (j = 0; j < sb.length(); j++) {
			if (sb.charAt(j) <= '9' && sb.charAt(j) >= '0' || sb.charAt(j) == '.') {
				num[k] += sb.charAt(j);
				continue;
			} else {
				command[k] = sb.charAt(j);
				k++;
			}
		}

		// 計(jì)算結(jié)果
		double result = 0;
		for (int i = 0; i < commandCount; i++) {

			// 取前兩個(gè)數(shù)，和第一個(gè)操作符，運(yùn)算
			double num1 = Double.parseDouble(num[i]);
			double num2 = Double.parseDouble(num[i + 1]);
			char cc = command[i];

			// 計(jì)算
			switch (cc) {
			case '+':
				result = num1 + num2;
				break;
			case '-':
				result = num1 - num2;
				break;
			case '*':
				result = num1 * num2;
				break;
			case '/':
				result = num1 / num2;
				break;
			case '%':
				result = num1 % num2;
				break;
			default:
				break;
			}
			num[i + 1] = String.valueOf(result);
		}

		return String.valueOf(result);
	}
	
	//主方法，運(yùn)行本類，顯示窗體
	public static void main(String[] args) {
		new Calculator().setVisible(true);
	}
}