COP 3337
  Section U05
  Spring 2017


                           The Largest Integer 
                           ===================



  I. The Program:
  ---------------

  import javax.swing.JOptionPane;

  public class Spring17COP3337Exceptions 
  {
  
      // compute the largest of a sequence of integers
      // the user enters the data from the JOptionPane
      public static void main(String[] args) 
      {
          System.out.println("The Largest of a Sequence of Integers");
          System.out.println("=====================================\n");
        
          String input = JOptionPane.showInputDialog("Enter an integer, click "
             + "on Cancel to finish.");
        
          // echo print the numbers
          System.out.println("\nThe integers:");
          System.out.println("-------------\n");
          // noIntegers is true as long as we haven't found an integer
          boolean noIntegers = true; 
          int largest = Integer.MIN_VALUE; // the current largest number
          // input is null when the user clicks on Quit
          while (input != null)
          {
              // try to get an integer
              try
              {
                  int current = Integer.parseInt(input);
                  System.out.printf("%10d\n",current);
                  if (noIntegers)
                  {
                      // initialize largest and set nointegers to false
                      largest = current;
                      noIntegers = false;
                  }    
                  else // largest is defined
                      if (current > largest)
                          largest = current; // update largest
                  input = JOptionPane.showInputDialog("Enter an integer, click "
                      + "on Cancel to finish.");
              }    
              catch (NumberFormatException e)
              {
                  System.out.println("Error: " + input + " is not an integer.");
                  input = JOptionPane.showInputDialog(input + " is not "
                      + "an integer. Try again or click on Cancel to finish.");
              }    
          }    
          // print the largest
          if (noIntegers)
              System.out.println("There are no integers, the largest is undefined.");
          else
              System.out.format("\nThe largest is %10d", largest);
          System.out.println();
      }  // end main    
  }





  II. The first Run:
  ------------------

  run:
  The Largest of a Sequence of Integers
  =====================================


  The integers:
  -------------

  Error: baba is not an integer.
          27
  Error: 15.3 is not an integer.
          25
          65
  Error: ali baba is not an integer.
          15

  The largest is         65
  BUILD SUCCESSFUL (total time: 1 minute 9 seconds)

  III. The Second Run
  -------------------

  run:
  The Largest of a Sequence of Integers
  =====================================


  The integers:
  -------------

  There are no integers, the largest is undefined.

  BUILD SUCCESSFUL (total time: 3 seconds)

  III. The Same Program Using the Console
  ---------------------------------------

  
  // import the scanner
  import java.util.Scanner;

  public class Spring17COP3337Exceptions2 
  {

      // compute the largest of a sequence of integers
      // the user enters the data from the console
      public static void main(String[] args) 
      {
          System.out.println("The Largest of a Sequence of Integers");
          System.out.println("=====================================\n");
        
          Scanner console = new Scanner(System.in);
        
          // echo print the numbers
          System.out.println("\nThe integers:");
          System.out.println("-------------\n");
          // noIntegers is true as long as we haven't found an integer
          boolean noIntegers = true; 
          int largest = Integer.MIN_VALUE; // the current largest number
          // input is null when the user clicks on Quit
          while (true)
          {
              // try to get an integer
              System.out.print("Enter an integer, a non-integer to finish > ");
              if (console.hasNextInt())
              {    
                   int current = console.nextInt(); // read the next int
                   if (noIntegers)
                   {
                       noIntegers = false;
                       // initialize largest
                       largest = current;
                   }
                   else // largest was initialized
                   {
                       // update largest
                       if (current > largest)
                           largest = current;
                   }    
              }  // end outer if
              else
                   break; // get out of the loop
          }
          // print the largest
          if (noIntegers)
              System.out.println("There are no integers, the largest is undefined.");
          else
              System.out.format("\nThe largest is %5d\n", largest);
      }  // end main    
    
  }
 
  IV. The Output Of the Second Program:
  -------------------------------------

  run:
  The Largest of a Sequence of Integers
  =====================================


  The integers:
  -------------

  Enter an integer, a non-integer to finish > 16
  Enter an integer, a non-integer to finish > -18
  Enter an integer, a non-integer to finish > 29
  Enter an integer, a non-integer to finish > 17
  Enter an integer, a non-integer to finish > AliBaba

  The largest is    29
  BUILD SUCCESSFUL (total time: 28 seconds)