编写一个程序，用户输入两个数，求其加减乘除，并用消息框显示计算结果。

代码：

//an complex program

import javax.swing.JOptionPane;//import class JOptionPane

public class Complex {

public static void main(String[] args) {

// TODO 自动生成的方法存根

String firstNumber,     //first string entered by user

       secondNumber;    //second string entered by user

int number1,            //first number to add

    number2,            //second number to add

    sum,                //sum of number1 and number2

    difference,         //difference of number1 and number2

    product,            //product of number1 and number2

    quotient;           //quotient of number1 and number2

// read in first number from user as a string

firstNumber = JOptionPane.showInputDialog("Enter first integer ");

//read in second number from user as a string

secondNumber = JOptionPane.showInputDialog("Enter second integer ");

//convert number from type string to type int

number1 = Integer.parseInt(firstNumber);

number2 = Integer.parseInt(secondNumber);

//add the numbers

sum = number1 + number2;

//difference the numbers

difference = number1-number2;

//product the numbers

product = number1 * number2;

//quotient the numbers

quotient = number1/number2;

//display the results

JOptionPane.showMessageDialog(

null,"The Sum is " + sum,"Results",JOptionPane.PLAIN_MESSAGE);

JOptionPane.showMessageDialog(

null,"The difference is " + difference,"Results",JOptionPane.PLAIN_MESSAGE);

JOptionPane.showMessageDialog(

null,"The product is " + product,"Results",JOptionPane.PLAIN_MESSAGE);

JOptionPane.showMessageDialog(

null,"The quotient is " + quotient,"Results",JOptionPane.PLAIN_MESSAGE);

System.exit(0);//terminate the program

}

}