java Swing 的一个简单的计算器
//实现了 =、-、+、*、/等基本的操作package Calculator;import java.awt.*;import java.awt.event.*;import javax.swing.*;public class Calculate extends JFrame {public static final int WIDTH = 500 ;public static final int HEIGHT = 400 ;private JTextField result; private JPanel mainPane; //主面板 private JPanel numPane; //数字面板 private JPanel operatePane; //操作符面板 private JPanel showPane; //显示面板 private JButton[] numB; //数字按钮 private JButton[] operateB; //操作符面板 public Calculate(String title){setTitle(title) ;result = new JTextField("0.0",22) ;result.setEditable(false) ;mainPane = new JPanel() ;numPane = new JPanel() ;operatePane = new JPanel() ;showPane = new JPanel() ;numB = new JButton ;for(int i=0; i<9; i++) { numB = new JButton(new Integer(i+1).toString()); } numB = new JButton("0"); numB = new JButton("cls"); numB = new JButton("."); //将数字按钮加到数字面板上numPane.setLayout(new GridLayout(4,3,1,1)) ;for(int i=0;i<12;i++)numPane.add(numB) ;operateB = new JButton ;operateB = new JButton("+"); operateB = new JButton("-"); operateB = new JButton("*"); operateB = new JButton("/"); operateB = new JButton("pow"); operateB = new JButton("sqrt"); operateB = new JButton("+/-"); operateB = new JButton("=");//把操作符按钮添加到操作面板上operatePane.setLayout(new GridLayout(4,2,1,1)) ;for(int i=0; i<8; i++) operatePane.add(operateB) ;showPane.setLayout(new BorderLayout()) ;showPane.add(result, BorderLayout.NORTH); mainPane.setLayout(new BorderLayout()) ;mainPane.add(showPane, BorderLayout.NORTH); mainPane.add(numPane, BorderLayout.WEST); mainPane.add(operatePane, BorderLayout.EAST); this.add(mainPane, BorderLayout.CENTER); this.setSize(WIDTH, HEIGHT); /*try{//将LookAndFeel设置成windows样式UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel") ;}catch(Exception e){e.printStackTrace() ;}*/Toolkit too = Toolkit.getDefaultToolkit() ;Dimension screenSize = too.getScreenSize() ;this.setLocation((screenSize.width-WIDTH)/2, (screenSize.height-HEIGHT)/2) ;this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE) ;this.setResizable(false); this.pack(); ButtonListener button = new ButtonListener() ;for(int i = 0; i < numB.length; i++)numB.addActionListener(button) ;for(int i=0;i<operateB.length;i++)operateB.addActionListener(button) ;}class ButtonListener implements ActionListener { private String last; //存储上一此操作符 private String strVal; //存储数字对应的字符串 private double total; //总数 private double number; //存储新输入的数 private boolean firsttime; //判断是否第一次按下的是操作符按钮 private boolean operatorPressed;//判断是否已经按过操作符按钮 public ButtonListener() { firsttime = true; strVal = ""; }//事件处理public void actionPerformed(ActionEvent e){String str = ((JButton)e.getSource()).getText().trim() ;if(Character.isDigit(str.charAt(0)))handleNumber(str) ;elsecalculate(str) ;}//判断是一元操作符还是二元操作符，并根据操作符类型做计算 public void calculate(String op) { operatorPressed = true; if(firsttime && !isUnary(op)) { total = getNumberOnDisplay(); firsttime = false; } if(isUnary(op)) { handleUnaryOp(op); } else if(last != null) { handleBinaryOp(last); } if(! isUnary(op)) { last = op; } } //判断是否一元操作符 public boolean isUnary(String s) { return s.equals("=") || s.equals("cls") || s.equals("sqrt") || s.equals("+/-") || s.equals("."); } //处理一元操作符 public void handleUnaryOp(String op) { if(op.equals("+/-")) {number = negate(getNumberOnDisplay() + ""); result.setText(""); result.setText(number + ""); return; }else if(op.equals(".")) { handleDecPoint(); return; }else if(op.equals("sqrt")) { number = Math.sqrt(getNumberOnDisplay()); result.setText(""); result.setText(number + ""); return; }else if(op.equals("=")) {// if(last!= null && !isUnary(last)) { handleBinaryOp(last); } last = null; firsttime = true; return; }else { clear(); } } //处理二元运算符 public void handleBinaryOp(String op) { if(op.equals("+")) { total +=number; }else if(op.equals("-")) { total -=number; }else if(op.equals("*")) { total *=number; }else if(op.equals("/")) { try { total /=number; }catch(ArithmeticException ae){} }else if(op.equals("pow")) total = Math.pow(total, number); //result.setText(""); last = null; // strVal = ""; number = 0; result.setText(total + ""); } //该方法用于处理数字按钮 public void handleNumber(String s) { if(!operatorPressed) { strVal += s; }else { operatorPressed = false; strVal = s; }number = new Double(strVal).doubleValue(); result.setText(""); result.setText(strVal); } //该方法用于按下"."按钮 public void handleDecPoint() { operatorPressed = false;if(strVal.indexOf(".")<0) { strVal += "."; } result.setText(""); result.setText(strVal); } //该方法用于将一个数求反 public double negate(String s) { operatorPressed = false; //如果是一个整数，去掉小数点后面的0 if(number == (int)number) { s = s.substring(0,s.indexOf(".")); } //如果无"-"增加在该数的前面 if(s.indexOf("-")<0) { strVal = "-" + s; } else { strVal = s.substring(1); } return new Double(strVal).doubleValue(); } //将显示框中的值转换成Double public double getNumberOnDisplay() { return new Double(result.getText()).doubleValue(); } //清除屏幕并设置所有的标识 public void clear() { firsttime = true; last = null; strVal = ""; total = 0; number = 0; result.setText("0"); } }public static void main(String[] args) { Calculate c = new Calculate("简单的计算器程序"); c.setVisible(true); } }
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