急需ｊａｖａ计算器小程序，在线等！！！！！！！

。。在论坛里看到一强人回的一个类似的贴子：
"把式子装在sql里丢数据库执行下"

import java.applet.*;
import java.awt.*;
import java.awt.event.*;
class Test extends Applet implements ActionListener
{
   Label l1,l2,l3;
   TextField t1,t2,t3;
   Button b1,b2,b3,b4;
   public void init()
   {
      l1=new Label("操作数");
      l2=new Label("被操作数");
      l3=new Label("结果");
      t1=new TextField(10);
      t2=new TextField(10);
      t3=new TextField(10);
      add(l1);
      add(t1);
      add(l2);
      add(t2);
      add(l3);
      add(t3);
      b1=new Button("加");
      b2=new Button("减");
      b3=new Button("乘");
      b4=new Button("除");
      add(b1);add(b2);add(b3);add(b4);
      b1.addActionListener(this);
      b2.addActionListener(this);
      b3.addActionListener(this);
      b4.addActionListener(this);
    }
    public void actionPerformed(ActionEvent j)
    {
      double n;
      try{
          if(j.getSource()==b1)
          {
           double n1,n2;
           n1=Double.parseDouble(t1.getText());
           n2=Double.parseDouble(t2.getText());
           n=n1+n2;
           t3.setText(String.valueOf(n));
          }
          if(j.getSource()==b2)
          {
           double n1,n2;
           n1=Double.parseDouble(t1.getText());
           n2=Double.parseDouble(t2.getText());
           n=n1-n2;
           t3.setText(String.valueOf(n));
          }
          if(j.getSource()==b3)
          {
           double n1,n2;
           n1=Double.parseDouble(t1.getText());
           n2=Double.parseDouble(t2.getText());
           n=n1*n2;
           t3.setText(String.valueOf(n));
          }
          if(j.getSource()==b4)
          {
           double n1,n2;
           n1=Double.parseDouble(t1.getText());
           n2=Double.parseDouble(t2.getText());
           n=n1/n2;
           t3.setText(String.valueOf(n));
          }
        }catch(Exception e){}
     }
}
不太明白ＬＺ的意思，一个小程序，applet吗？在命令行执行，从键盘输入吗？写了个applet的．

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;public class Calculator
{
   public static void main(String[] args)
   {
      CalculatorFrame frame = new CalculatorFrame();
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.setVisible(true);
   }
}/**
   A frame with a calculator panel.
*/
class CalculatorFrame extends JFrame
{
   public CalculatorFrame()
   {
      setTitle("Calculator");
      CalculatorPanel panel = new CalculatorPanel();
      add(panel);
      pack();
   }
}/**
   A panel with calculator buttons and a result display.
*/
class CalculatorPanel extends JPanel
{
   public CalculatorPanel()
   {
      setLayout(new BorderLayout());      result = 0;
      lastCommand = "=";
      start = true;

      // add the display      display = new JButton("0");
      display.setEnabled(false);
      add(display, BorderLayout.NORTH);

      ActionListener insert = new InsertAction();
      ActionListener command = new CommandAction();      // add the buttons in a 4 x 4 grid      panel = new JPanel();
      panel.setLayout(new GridLayout(4, 4));      addButton("7", insert);
      addButton("8", insert);
      addButton("9", insert);
      addButton("/", command);      addButton("4", insert);
      addButton("5", insert);
      addButton("6", insert);
      addButton("*", command);      addButton("1", insert);
      addButton("2", insert);
      addButton("3", insert);
      addButton("-", command);      addButton("0", insert);
      addButton(".", insert);
      addButton("=", command);
      addButton("+", command);      add(panel, BorderLayout.CENTER);
   }   /**
      Adds a button to the center panel.
      @param label the button label
      @param listener the button listener
   */
   private void addButton(String label, ActionListener listener)
   {
      JButton button = new JButton(label);
      button.addActionListener(listener);
      panel.add(button);
   }   /**
      This action inserts the button action string to the
      end of the display text.
   */
   private class InsertAction implements ActionListener
   {
      public void actionPerformed(ActionEvent event)
      {
         String input = event.getActionCommand();
         if (start)
         {
            display.setText("");
            start = false;
         }
         display.setText(display.getText() + input);
      }
   }   /**
      This action executes the command that the button
      action string denotes.
   */
   private class CommandAction implements ActionListener
   {
      public void actionPerformed(ActionEvent event)
      {
         String command = event.getActionCommand();         if (start)
         {
            if (command.equals("-"))
            {
               display.setText(command);
               start = false;
            }
            else
               lastCommand = command;
         }
         else
         {
            calculate(Double.parseDouble(display.getText()));
            lastCommand = command;
            start = true;
         }
      }
   }   /**
      Carries out the pending calculation.
      @param x the value to be accumulated with the prior result.
   */
   public void calculate(double x)
   {
      if (lastCommand.equals("+")) result += x;
      else if (lastCommand.equals("-")) result -= x;
      else if (lastCommand.equals("*")) result *= x;
      else if (lastCommand.equals("/")) result /= x;
      else if (lastCommand.equals("=")) result = x;
      display.setText("" + result);
   }

   private JButton display;
   private JPanel panel;
   private double result;
   private String lastCommand;
   private boolean start;
}

是不是这样：
class Jis
{
public static void main(String[] args)
{
int num1,num2;
int n;
char op='s';
num1=Integer.parseInt(args[0]);
num2=Integer.parseInt(args[2]);
op=args[1].charAt(0);
switch(op)
{
case '+':
n=num1+num2;
System.out.print(""+num1+"+"+num2+"="+n);
break;
case '-':
n=num1-num2;
System.out.print(""+num1+"-"+num2+"="+n);
break;
case '/':
n=num1/num2;
System.out.print(""+num1+"/"+num2+"="+n);
break;
case 'x':
n=num1*num2;
System.out.print(""+num1+"*"+num2+"="+n);
break;
}
}
}

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Calculator extends JFrame implements ActionListener
{
private boolean dotExist, operated, equaled; // 帮助运算的布尔变量
private double storedNumber; // 目前的结果
private char lastOperator; // 表示上一运算符
private JTextField operation; // 结果栏
private JButton dot, plus, minus, multi, div, sqrt, equal, changePN, clear; // 运算符
private JButton[] numbers; // 数字
// 构造者
public Calculator()
{
setTitle("Calculator");
// 初始化变量
dotExist = false; // 表示当前的数是否有小数点
operated = false; // 表示任意运算符是否被按下
equaled = false; // 表示等号是否被按下
storedNumber = 0;
lastOperator = '?';
// 初始化窗口变量
operation = new JTextField("0");
operation.setEditable(false);
numbers = new JButton[10];
for (int i = 0; i < 10; i++)
numbers[i] = new JButton("" + i);
dot = new JButton(".");
plus = new JButton("+");
minus = new JButton("-");
multi = new JButton("*");
div = new JButton("/");
sqrt = new JButton("√");
equal = new JButton("=");
changePN = new JButton("±");
clear = new JButton("AC");
// 将窗口物体放入窗口
GridBagLayout layout = new GridBagLayout();
getContentPane().setLayout(layout);
addComponent(layout, operation, 0, 0, 4, 1);
addComponent(layout, numbers[1], 1, 0, 1, 1);
addComponent(layout, numbers[2], 1, 1, 1, 1);
addComponent(layout, numbers[3], 1, 2, 1, 1);
addComponent(layout, numbers[4], 2, 0, 1, 1);
addComponent(layout, numbers[5], 2, 1, 1, 1);
addComponent(layout, numbers[6], 2, 2, 1, 1);
addComponent(layout, numbers[7], 3, 0, 1, 1);
addComponent(layout, numbers[8], 3, 1, 1, 1);
addComponent(layout, numbers[9], 3, 2, 1, 1);
addComponent(layout, dot, 4, 0, 1, 1);
addComponent(layout, numbers[0], 4, 1, 1, 1);
addComponent(layout, sqrt, 4, 2, 1, 1);
addComponent(layout, plus, 1, 3, 1, 1);
addComponent(layout, minus, 2, 3, 1, 1);
addComponent(layout, multi, 3, 3, 1, 1);
addComponent(layout, div, 4, 3, 1, 1);
addComponent(layout, equal, 5, 0, 2, 1);
addComponent(layout, changePN, 5, 2, 1, 1);
addComponent(layout, clear, 5, 3, 1, 1);
}
// 对按钮进行反应的方法
public void actionPerformed(ActionEvent e)
{
JButton btn = (JButton)e.getSource();
if (btn == clear)
{
operation.setText("0");
dotExist = false;
storedNumber = 0;
lastOperator = '?';
}
else if (btn == equal)
{
operate('=');
equaled = true;
}
else if (btn == plus)
{
operate('+');
equaled = false;
}
else if (btn == minus)
{
operate('-');
equaled = false;
}
else if (btn == multi)
{
operate('*');
equaled = false;
}
else if (btn == div)
{
operate('/');
equaled = false;
}
else if (btn == changePN)
{
operate('p');
operate('=');
equaled = true;
}
else if (btn == sqrt)
{
operate('s');
operate('=');
equaled = true;
}
else
{
if (equaled)
storedNumber = 0;
for (int i = 0; i < 10; i++)
if (btn == numbers[i])
{
if (operation.getText().equals("0"))
operation.setText("" + i);
else if(! operated)
operation.setText(operation.getText() + i);
else
{
operation.setText("" + i);
operated = false;
}
}
if (btn == dot && ! dotExist)
{
operation.setText(operation.getText() + ".");
dotExist = true;
}
}
}
// 进行运算的方法
private void operate(char operator)
{
double currentNumber = Double.valueOf(operation.getText()).doubleValue();
if (lastOperator == '?')
storedNumber = currentNumber;
else if (lastOperator == '+')
storedNumber += currentNumber;
else if (lastOperator == '-')
storedNumber -= currentNumber;
else if (lastOperator == '*')
storedNumber *= currentNumber;
else if (lastOperator == '/')
storedNumber /= currentNumber;
else if (lastOperator == 'p')
storedNumber *= -1;
else if (lastOperator == 's')
storedNumber = Math.sqrt(currentNumber);
else if (lastOperator == '=' && equaled)
storedNumber = currentNumber;
operation.setText("" + storedNumber);
operated = true;
lastOperator = operator;
}
// 快捷使用GridBagLayout的方法
private void addComponent(GridBagLayout layout, Component component, int row, int col, int width, int height)
{
GridBagConstraints constraints = new GridBagConstraints();
constraints.fill = GridBagConstraints.BOTH;
constraints.insets = new Insets(10, 2, 10, 2);
constraints.weightx = 100;
constraints.weighty = 100;
constraints.gridx = col;
constraints.gridy = row;
constraints.gridwidth = width;
constraints.gridheight = height;
layout.setConstraints(component, constraints);
if (component instanceof JButton)
((JButton)component).addActionListener(this);
getContentPane().add(component);
}
// 主方法初始化并显示窗口
public static void main(String[] args)
{
Calculator calc = new Calculator();
calc.setSize(290, 400);
calc.setVisible(true);
}
}

楼主都说了不要Applet了,大家要遵守需求哦~我自己写了一个,用了3小时...有点麻烦,似乎可以简化,不过能用,控制台录入表达式,支持小数加减乘除,不支持括号./*
* Created on 2007-7-12
*/
package willishz.soho.arithmetic;import java.util.ArrayList;
import java.util.Scanner;/**
* calculate an expression(end with "=", decimal supported, brackets unsupported).
* @author willishz
*/
public class ExpressionCalculator {    public static final char PLUS = '+';
    public static final char SUBTRACT = '-';
    public static final char MULTIPLE = '*';
    public static final char DIVIDE = '/';
    public static final char DECIMAL = '.';
    public static final char EQUAL = '=';

    public static final String PLUS_STR = "+";
    public static final String SUBTRACT_STR = "-";
    public static final String MULTIPLE_STR = "*";
    public static final String DIVIDE_STR = "/";

    /**
     * interpret expression string to units.
     * @param expression
     * @return
     */
    public static String interpret(String expression) {
        ArrayList explist = new ArrayList();
        int flg = 0; // flag to divide expression units
        StringBuffer sb = new StringBuffer();
        char[] expChars = expression.toCharArray();
        // expression string to units
        for (int i = 0; i < expChars.length; i++) {
            // expression divided by operators
            if (expChars[i] == ExpressionCalculator.EQUAL || expChars[i] == ExpressionCalculator.PLUS || expChars[i] == ExpressionCalculator.SUBTRACT || expChars[i] == ExpressionCalculator.MULTIPLE || expChars[i] == ExpressionCalculator.DIVIDE) {
                // paste digits of number between each two segments
                for (int j = flg; j < i; j++) {
                    sb.append(expChars[j]);
                    flg = i + 1;
                }
                // sucess divide a unit
                explist.add(sb.toString());
                // expression end with "=", paste last digits of number
                if (expChars[i] != ExpressionCalculator.EQUAL) {
                    explist.add(String.valueOf(expChars[i]));
                }
                sb = new StringBuffer();
            }
        }
        // calculate this expression units
        return ExpressionCalculator.calculate(explist);
    }

    /**
     * calculate all units.
     * @param explist
     * @return
     */
    public static String calculate(ArrayList explist) {
        do {
            int operatorIndex = -1; // operator location
            // count operator, first multiple and divide
            if (explist.indexOf(ExpressionCalculator.PLUS_STR) > 0 && explist.indexOf(ExpressionCalculator.DIVIDE_STR) > 0) { // both
                operatorIndex = Math.min(explist.indexOf(ExpressionCalculator.PLUS_STR), explist.indexOf(ExpressionCalculator.DIVIDE_STR));
            } else if ((explist.indexOf(ExpressionCalculator.PLUS_STR) > 0 && explist.indexOf(ExpressionCalculator.DIVIDE_STR) < 0)) { // multiple only
                operatorIndex = explist.indexOf(ExpressionCalculator.PLUS_STR);
            } else if ((explist.indexOf(ExpressionCalculator.PLUS_STR) < 0 && explist.indexOf(ExpressionCalculator.DIVIDE_STR) > 0)) { // divide only
                operatorIndex = explist.indexOf(ExpressionCalculator.DIVIDE_STR);
            }

            //  finish counting multiple or divide operator
            if (operatorIndex > 0) { // do have multiple or divide operator
                explist = execute(explist, operatorIndex); // multiple or divide operation
                continue; // continue calculate
            }

            // no multiple or divide operation, count plus and subtract operator
            if (explist.indexOf(ExpressionCalculator.PLUS_STR) > 0 && explist.indexOf(ExpressionCalculator.SUBTRACT_STR) > 0) { // both
                operatorIndex = Math.min(explist.indexOf(ExpressionCalculator.PLUS_STR), explist.indexOf(ExpressionCalculator.SUBTRACT_STR));
            } else if ((explist.indexOf(ExpressionCalculator.PLUS_STR) > 0 && explist.indexOf(ExpressionCalculator.SUBTRACT_STR) < 0)) { // plus only
                operatorIndex = explist.indexOf(ExpressionCalculator.PLUS_STR);
            } else if ((explist.indexOf(ExpressionCalculator.PLUS_STR) < 0 && explist.indexOf(ExpressionCalculator.SUBTRACT_STR) > 0)) { // substract only
                operatorIndex = explist.indexOf(ExpressionCalculator.SUBTRACT_STR);
            }

            //  finish counting plus or subtract operator
            if (operatorIndex > 0) { // do have plus or subtract operator
                explist = execute(explist, operatorIndex); // plus or subtract operation
                continue; // continue calculate
            }

            // no operators
        return explist.get(0).toString(); // return result
        } while(true);
    }

    /**
     * calculate two units.
     * @param explist
     * @return
     */
    public static ArrayList execute(ArrayList explist, int operatorIndex) {
        double unit1 = Double.valueOf(explist.get(operatorIndex - 1).toString()).doubleValue(); // get factor1
        double unit2 = Double.valueOf(explist.get(operatorIndex + 1).toString()).doubleValue(); // get factor2
        char operator = explist.get(operatorIndex).toString().charAt(0); // get operator
        // estimate operator, do calculate, then rebuild arraylist
        switch (operator) {
        case ExpressionCalculator.PLUS:
            explist.set(operatorIndex - 1, String.valueOf(unit1 + unit2));
            explist.remove(operatorIndex + 1);
            explist.remove(operatorIndex);
            break;
        case ExpressionCalculator.SUBTRACT:
            explist.set(operatorIndex - 1, String.valueOf(unit1 - unit2));
            explist.remove(operatorIndex + 1);
            explist.remove(operatorIndex );
            break;
        case ExpressionCalculator.MULTIPLE:
            explist.set(operatorIndex - 1, String.valueOf(unit1 * unit2));
            explist.remove(operatorIndex + 1);
            explist.remove(operatorIndex);
            break;
        case ExpressionCalculator.DIVIDE:
            explist.set(operatorIndex - 1, String.valueOf(unit1 / unit2));
            explist.remove(operatorIndex + 1);
            explist.remove(operatorIndex);
            break;
        }
        return explist;
    }

    public static void main(String[] args) {
        System.out.print("请输入一个表达式以 \"=\" 结束(中间不加空格, 支持小数, 不支持括号): ");
        Scanner sc = new Scanner(System.in); // from console
        System.out.println(ExpressionCalculator.interpret(sc.next()));
        System.exit(0);
    }
}

调试易

急需ｊａｖａ计算器小程序，在线等！！！！！！！

解决方案 »