sentinels.java

《A first book of java》by Gary J.Bronson 北大出版社

import javax.swing.*;
public class Sentinels
{
  public static void main(String[] args)
  {
    final double HIGHGRADE = 100.0;
    String s1, outMessage;
    double grade, total;
    grade = 0;
    total = 0;
    outMessage = "To stop entering grades, type in any number"
               + "\n greater than 100.";
    JOptionPane.showMessageDialog(null, outMessage, 
                                  "Program 5.8", 
                                  JOptionPane.INFORMATION_MESSAGE);
  
    s1 = JOptionPane.showInputDialog("Enter a grade:");
    grade = Double.parseDouble(s1);
  
    while (grade <= HIGHGRADE)
    {
      total = total + grade;
      s1 = JOptionPane.showInputDialog("Enter a grade:");
      grade = Double.parseDouble(s1);
    }
  
    JOptionPane.showMessageDialog(null, "The total of the grades is " + total, 
                                  "Program 5.8", 
                                  JOptionPane.INFORMATION_MESSAGE);
    System.exit(0);  
  }
}