Few Tricky Programs in Java

1. Comments that execute :

   Till now, we were always taught “Comments do not Execute”. Let us see today “The comments that execute”

   Following is the code snippet:

   public class Testing {
       public static void main(String[] args)
        {
            // the line below this gives an output
            // \u000d System.out.println("comment executed");
        }
   }

   Output:

   comment executed

   The reason for this is that the Java compiler parses the unicode character \u000d as a new line and gets transformed into:

   public class Testing {
       public static void main(String[] args)
       {
           // the line below this gives an output
           // \u000d
           System.out.println("comment executed");
       }
   }
2. Named loops :

   // A Java program to demonstrate working of named loops.
   public class Testing
   {
       public static void main(String[] args)
       {
       loop1:
       for (int i = 0; i < 5; i++)
        {
           for (int j = 0; j < 5; j++)
           {
               if (i == 3)
                   break loop1;
               System.out.println("i = " + i + " j = " + j);
           }
       }
      }
   }

   Output:

   i = 0 j = 0
   i = 0 j = 1
   i = 0 j = 2
   i = 0 j = 3
   i = 0 j = 4
   i = 1 j = 0
   i = 1 j = 1
   i = 1 j = 2
   i = 1 j = 3
   i = 1 j = 4
   i = 2 j = 0
   i = 2 j = 1
   i = 2 j = 2
   i = 2 j = 3
   i = 2 j = 4

   You can also use continue to jump to start of the named loop.

   We can also use break (or continue) in a nested if-else with for loops in order to break several loops with if-else, so one can avoid setting lot of flags and testing them in the if-else in order to continue or not in this nested level.