addition.java

一个用JAVA编写的加法程序

// Fig. 2.9: Addition.java
// Addition program that displays the sun of two numbers.

//Java packages
import javax.swing.JOptionPane; // proram uses JOptionPane

public class Addition{

   // main method begins execution of Java application
   public static void main( String args[] )
   {
      String firstNumber;  // first string entered by user
      String secondNumber; // second string entered by user   

      int number1;         // first number to add
      int number2;         // second number to add
      int sum;             // sum 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 numbers from type string to type int
      number1 = Integer.parseInt( firstNumber );
      number2 = Integer.parseInt( secondNumber );

      // add numbers
      sum = number1 + number2;

      // display results ( but no preference3 and 4 )
      JOptionPane.showMessageDialog( null, "the sum is " + sum, "Results", JOptionPane.PLAIN_MESSAGE );

      System.exit( 0 ); // terminate application with window
 
   } // end main method

} // end class Addition