原创：经典案例-计算器源码(核心功能)

计算器面板

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;

import javax.swing.JButton;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.border.EmptyBorder;

public class CalPanel extends JPanel implements ActionListener, FocusListener {

	private static final long serialVersionUID = 8219086268145903430L;

	private JTextField jtfShow = new JTextField();

	private JButton[] jbFun1;
	private JButton[] jbFun2;
	private JButton[] jbOper;

	private JPanel jpTxt = new JPanel();
	private JPanel jpMain = new JPanel();
	private JPanel jpLeftBtns = new JPanel();
	private JPanel jpMainTopBtns = new JPanel();
	private JPanel jpMainBtns = new JPanel();

	private double x;
	private double y;
	// +0 -1 *2 /3 %5 无效-1
	private int oper;
	// true 正在输入， false 等待输入
	private boolean inputState;
	// true 有小数点， false 无小数点
	private boolean pointState;

	public CalPanel() {
		String[] strFunBtn1 = { "", "MC", "MR", "MS", "M+" };
		String[] strFunBtn2 = { "Backspace", "CE", "C" };
		String[] strOperBtn = { "7", "8", "9", "/", "sqrt", "4", "5", "6", "*",
				"%", "3", "2", "1", "-", "1/x", "0", "+/-", ".", "+", "=" };
		this.setLayout(new BorderLayout(10, 10));
		this.setBorder(new EmptyBorder(5, 5, 5, 5));

		jbFun1 = new JButton[strFunBtn1.length];
		jbFun2 = new JButton[strFunBtn2.length];
		jbOper = new JButton[strOperBtn.length];

		jpTxt.setLayout(new BorderLayout());
		jpLeftBtns.setLayout(new GridLayout(5, 1, 3, 3));
		jpMain.setLayout(new BorderLayout(10, 10));
		jpMainTopBtns.setLayout(new GridLayout(1, 3, 3, 3));
		jpMainBtns.setLayout(new GridLayout(4, 5, 3, 3));

		jpMain.add(jpMainTopBtns, BorderLayout.NORTH);
		jpMain.add(jpMainBtns, BorderLayout.CENTER);

		jpTxt.add(jtfShow);
		

		for (int i = 0; i < jbFun1.length; i++) {
			jbFun1[i] = new JButton(strFunBtn1[i]);
			jpLeftBtns.add(jbFun1[i]);
		}
		
		for (int i = 0; i < jbFun2.length; i++) {
			jbFun2[i] = new JButton(strFunBtn2[i]);
			jpMainTopBtns.add(jbFun2[i]);
		}
		
		for (int i = 0; i < jbOper.length; i++) {
			jbOper[i] = new JButton(strOperBtn[i]);
			jpMainBtns.add(jbOper[i]);
		}

		this.add(jpTxt, BorderLayout.NORTH);
		this.add(jpLeftBtns, BorderLayout.WEST);
		this.add(jpMain, BorderLayout.CENTER);
		
		setComponentProp();
		addEventHandle();
		init();
	}
	
	/**
	 * 初始化
	 */
	private void init() {
		x = 0.0;
		y = 0.0;
		inputState = false;
		pointState = false;
		oper = -1;
		this.jtfShow.setText("0.");
	}
	/**
	 * 设置控件属性
	 */
	private void setComponentProp() {
		jtfShow.setFont(new Font("", 0, 16));
		jtfShow.setEditable(false);
		jtfShow.setHorizontalAlignment(JTextField.RIGHT);
		jtfShow.setBackground(Color.WHITE);
		
		for (int i = 0; i < jbFun1.length; i++) {
			jbFun1[i].setForeground(Color.red);
			if ("".equals(jbFun1[i].getText().trim())) {
				jbFun1[i].setEnabled(false);
			}
		}
		
		for (int i = 0; i < jbFun2.length; i++) {
			jbFun2[i].setForeground(Color.red);
		}
		
		for (int i = 0; i < jbOper.length; i++) {
			jbOper[i].setForeground(Color.blue);
			if (-1 != ("+-*/=".indexOf(jbOper[i].getText().trim()))) {
				jbOper[i].setForeground(Color.red);
			}
		}
	}

	/**
	 * 注册事件
	 */
	private void addEventHandle() {
		jtfShow.addFocusListener(this);
		
		for (int i = 0; i < jbFun1.length; i++) {
			jbFun1[i].addActionListener(this);
		}
		
		for (int i = 0; i < jbFun2.length; i++) {
			jbFun2[i].addActionListener(this);
		}
		
		for (int i = 0; i < jbOper.length; i++) {
			jbOper[i].addActionListener(this);
		}
	}
	
	@Override
	public void actionPerformed(ActionEvent e) {
		// TODO Auto-generated method stub
		if (e.getSource() instanceof JButton) {
			JButton jb = (JButton) (e.getSource());
			String btnText=jb.getText().trim();
			if (-1 != ("1234567890".indexOf(btnText))) {
				// 数字
				this.numberInput(btnText);
			} else if (".".equals(jb.getText().trim())) {
				// 待处理
				this.pointInput();
			} else if (-1 != ("+-*/%".indexOf(jb.getText().trim()))) {
				//操作符
				this.operInput(jb.getText().trim());
			} else if ("=".equals(jb.getText().trim())) {
				//等号
				this.equalInput();
			} else if ("CE".equals(jb.getText().trim())) {
				//清除显示
				this.CEInput();
			} else if ("C".equals(jb.getText().trim())) {
				//重置计算器
				this.init();
			}
		}
	}

	/**
	 * 数字输入
	 */
	private void numberInput(String numText) {
		StringBuilder sbNum = new StringBuilder(jtfShow.getText()
				.trim());
		if (inputState) {
			if (pointState) {
				this.jtfShow.setText(sbNum.toString()
						+ numText);
			} else {
				sbNum.insert(sbNum.length() - 1, numText);
				this.jtfShow.setText(sbNum.toString());
			}
		} else {
			this.jtfShow.setText(numText + ".");
			inputState = true;
		}
	}
	/**
	 * 小数点输入
	 */
	private void pointInput() {
		if(!inputState) this.jtfShow.setText("0.");
		inputState = true;
		pointState = true;
	}
	/**
	 * 等号输入
	 */
	private void equalInput() {
		if(inputState) {
			y = Double.parseDouble(jtfShow.getText().trim());
		}
		caculate();
		jtfShow.setText(FormatUitl.formatDouble(x));
		inputState = false;
		pointState = false;
	}
	/**
	 * 双目操作符操作
	 */
	private void operInput(String strOper) {
		if (inputState) {
			y = Double.parseDouble(jtfShow.getText().trim());
			caculate();
			jtfShow.setText(FormatUitl.formatDouble(x));
		} else {
			y = x;
		}
		if ("+".equals(strOper)) {
			oper = 0;
		} else if ("-".equals(strOper)) {
			oper = 1;
		} else if ("*".equals(strOper)) {
			oper = 2;
		} else if ("/".equals(strOper)) {
			oper = 3;
		} else if ("%".equals(strOper)) {
			oper = 4;
		}

		inputState = false;
		pointState = false;
	}
	/**
	 * CE输入
	 */
	private void CEInput() {
		jtfShow.setText("0.");
		inputState = false;
		pointState = false;
	}
	/**
	 * 计算操作
	 */
	private void caculate() {
		switch (oper) {
		case 0:
			x += y;
			break;
		case 1:
			x -= y;
			break;
		case 2:
			x *= y;
			break;
		case 3:
			x /= y;
			break;
		case 4:
			x %= y;
			break;
		default:
			x = y;
		}
	}
	
	@Override
	public void focusGained(FocusEvent e) {
		// TODO Auto-generated method stub
		jtfShow.setFocusable(false);
	}

	@Override
	public void focusLost(FocusEvent e) {
		// TODO Auto-generated method stub

	}
}

 

计算机器菜单

 

import java.awt.event.InputEvent;
import java.awt.event.KeyEvent;

import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.KeyStroke;


public class CalJMenuBar extends JMenuBar{
	private static final long serialVersionUID = 8787168962144176764L;
	private JMenu[] mainMenu;
	private JMenuItem[] editMenuItem;
	private JMenuItem[] viewMenuItem;
	private JMenuItem[] helpMenuItem;
	
	public CalJMenuBar() {
		mainMenu=new JMenu[3];
		mainMenu[0]=new JMenu("编辑(E)");
		mainMenu[1]=new JMenu("查看(V)");
		mainMenu[2]=new JMenu("帮助(H)");
		
		editMenuItem=new JMenuItem[2];
		editMenuItem[0]=new JMenuItem("复制(C)");
		editMenuItem[1]=new JMenuItem("粘贴(P)");
		
		viewMenuItem=new JMenuItem[3];
		viewMenuItem[0]=new JMenuItem("标准型(T)");
		viewMenuItem[1]=new JMenuItem("科学型(S)");
		viewMenuItem[2]=new JMenuItem("数字分组(I)");
		
		helpMenuItem=new JMenuItem[2];
		helpMenuItem[0]=new JMenuItem("帮助主题(H)");
		helpMenuItem[1]=new JMenuItem("关于计算器(A)");
		for(int i=0;i<mainMenu.length;i++) {
			this.add(mainMenu[i]);
		}
		
		for(int i=0;i<editMenuItem.length;i++) {
			mainMenu[0].add(editMenuItem[i]);
		}
		
		mainMenu[1].add(viewMenuItem[0]);
		mainMenu[1].add(viewMenuItem[1]);
		mainMenu[1].addSeparator();
		mainMenu[1].add(viewMenuItem[2]);
		
		mainMenu[2].add(helpMenuItem[0]);
		mainMenu[2].addSeparator();
		mainMenu[2].add(helpMenuItem[1]);
		
		this.addShortKey();
		this.addAccelaratorKey();
	}
	public void addShortKey() {
		mainMenu[0].setMnemonic(KeyEvent.VK_E);
		mainMenu[1].setMnemonic('V');
		mainMenu[2].setMnemonic('H');
		
		viewMenuItem[0].setMnemonic('T');
		viewMenuItem[1].setMnemonic('S');
		viewMenuItem[2].setMnemonic('I');
		
		editMenuItem[0].setMnemonic('C');
		editMenuItem[1].setMnemonic('P');
		
		helpMenuItem[0].setMnemonic('H');
		helpMenuItem[1].setMnemonic('A');
	}
	public void addAccelaratorKey() {
		editMenuItem[0].setAccelerator(KeyStroke.getKeyStroke('C', InputEvent.CTRL_MASK));
		editMenuItem[1].setAccelerator(KeyStroke.getKeyStroke('V', InputEvent.CTRL_MASK));
	}
}

 工具类

public class FormatUitl {
	public static  String formatDouble(double n) {
		StringBuilder sbNum = new StringBuilder(Double.toString(n));
		while (true) {
			if (sbNum.charAt(sbNum.length() - 1) == '0') {
				sbNum.deleteCharAt(sbNum.length() - 1);
			} else {
				break;
			}
		}
		return sbNum.toString();
	}
}

  窗体及整合

import javax.swing.JFrame;
import javax.swing.JMenuBar;
import javax.swing.JPanel;
import javax.swing.UnsupportedLookAndFeelException;

public class Calculator {
	public static void main(String[] args) throws ClassNotFoundException, InstantiationException, IllegalAccessException, UnsupportedLookAndFeelException {
		//UIManager.setLookAndFeel((UIManager.getInstalledLookAndFeels())[3].getClassName());
		JPanel calPanel=new CalPanel();
		JMenuBar calMenu=new CalJMenuBar();
		JFrame jf=new JFrame("计算器 Mr.Rong 制作");
		//jdk 1.4 jf.getContentPane().add();
		
		//jdk 1.5 以后
		jf.add(calPanel);
		jf.pack();
		jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		jf.setVisible(true);
		jf.setResizable(false);
		jf.setJMenuBar(calMenu);	
		
	}
}