java 实现 计算器

import javax.swing.*; import java.awt.*; import java.awt.event.*; public class cal_sim_new extends JFrame { public static void main(String args[]) { new cal_sim_new(); } cal_sim_new() { super("简单计算器"); this.add(new Label("operator"),BorderLayout.NORTH); this.add(new cPanel(),BorderLayout.CENTER); this.add(new Label(),BorderLayout.WEST); this.add(new Label(),BorderLayout.EAST); this.add(new Label(),BorderLayout.SOUTH); this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); this.setSize(200,253); this.setLocation (200,200); this.setVisible(true); } class cPanel extends JPanel { JTextField tfResult; JButton[] btn = new JButton[17]; public cPanel() { this.setLayout(new GridBagLayout()); GridBagConstraints c = new GridBagConstraints(); c.fill = GridBagConstraints.BOTH; c.gridwidth = 4; this.add(new JLabel("JAVA计算器",JLabel.CENTER),c); tfResult = new JTextField(); tfResult.setHorizontalAlignment(JTextField.CENTER); tfResult.setEditable (false); tfResult.setBackground (Color.WHITE); tfResult.addKeyListener(new KeyAdapter() { public void keyTyped(KeyEvent e) { char c = e.getKeyChar(); e.consume(); if(27==c)// esc键 process('退'); if(10==c)// enter键 process('='); else if(c=='c') process('清'); else if(cal.isOper(c) || '0'<=c&&c<='9') process(c); } }); c.gridy = 1; this.add(tfResult,c); String s = "退出,清除,7,8,9,/,4,5,6,*,1,2,3,-,0,=,+"; String[] as = s.split(","); BtnListener bl = new BtnListener(); for(int i=0; i<as.length; i++) { btn[i] = new JButton(as[i]); btn[i].addActionListener(bl); } int i=0; c.gridx = 0 ; c.gridy = 2; c.gridwidth = 2; c.gridheight = 1; this.add(btn[i++],c); c.gridx = 2; this.add(btn[i++],c); c.gridwidth = 1; for(int j=3; j<6; j++) { c.gridy = j; for(int k=0; k<4; k++) { c.gridx = k; this.add(btn[i++],c); } } c.gridy = 6; c.gridx = 0; this.add(btn[i++],c); c.gridx = 1; c.gridwidth = 2; this.add(btn[i++],c); c.gridx = 3; c.gridwidth = 1; this.add(btn[i++],c); } class BtnListener implements ActionListener { public void actionPerformed(ActionEvent e) { JButton cBtn = (JButton)e.getSource(); String str = cBtn.getText(); process(str.charAt(0)); } } // 根据键盘或者鼠标操作，响应一个字符的操作，比如输入数字或者清除 int flag = 0; // 标记最后一次输入是否为数字 cal c = new cal(); void process(char ch) { if(ch=='退') { System.exit(0); } else if(ch=='清') { tfResult.setText(""); c.makeEmpty(); flag = 0; } else if(ch=='=') { // 判断当前显示是否为输入的 if(1==flag) { String reStr = c.update(tfResult.getText()); // 判断返回值是否为空，为空则正常显示，不为空则其为错误提示信息 if(reStr.equals("")) tfResult.setText(c.getResult()+""); else tfResult.setText(reStr); flag = 0; } else { tfResult.setText(c.getResult()+""); } } else if(cal.isOper(ch))// 若是操作符 { if(1==flag) { String reStr = c.update(tfResult.getText()); // 判断返回值是否为空，为空则正常显示，不为空则其为错误提示信息 if(reStr.equals("")) { c.update(ch+""); tfResult.setText(ch+""); } else tfResult.setText(reStr); flag = 0; } else { c.update(ch+""); tfResult.setText(ch+""); } } else// 操作数 { if(1==flag) tfResult.setText(tfResult.getText()+ch); else { // 判断是否为一次新的计算 String str = tfResult.getText(); if(str.equals("") || !cal.isOper(str)) c.makeEmpty(); tfResult.setText(ch+""); flag = 1; // 标记最后一个为数字 } } } } } class cal { double result; // 运算结果 double opNum; // 操作数 char ch; // 操作符 cal() { this.makeEmpty(); } void makeEmpty() { this.result = 0; this.opNum = 0; this.ch = 0; System.out.println("计算数据清空"); } static boolean isOper(char ch) { String op = "+-*/"; for(int i=0; i<op.length(); i++) { if(op.charAt(i) == ch ) return true; } return false; } static boolean isOper(String str) { if(str.length() != 1) return false; String op = "+-*/"; for(int i=0; i<op.length(); i++) { if( op.charAt(i) == str.charAt(0)) return true; } return false; } // 运算方法，若成功返回一个空字符串，失败则返回一个包含错误提示的字符串 String update(String str) { if(0==str.length())// 调试用 { System.out.println("null"); return ""; } if(isOper(str))// 若是一个操作符 { ch = str.charAt(0); System.out.println("得到一个操作符："+str); } else// 若为一个操作数，则先转换为double类型 { try{ opNum = Double.parseDouble(str); }catch(NumberFormatException e) { this.makeEmpty(); return "程序出现操作数转换异常!"; } if(ch!=0)// 操作符不为零则开始进行运算 { System.out.print("得到一个操作数"+opNum+"，开始进行运算："+result+ch+opNum+"="); if(ch=='+') { result += opNum; } else if(ch == '-') { result -= opNum; } else if(ch == '*') { result *= opNum; } else { if(opNum != 0) { result /= opNum; } else { this.makeEmpty(); return "除数不能为零"; } } System.out.println(result); } else { System.out.println("得到一个操作数:"+opNum); result = opNum; } } return ""; } double getResult() { return result; } }