USING BLOCKS OF CODE

(*) Java allows two or more statements to be grouped into blocks of code, also called 
      code blocks.This is done by enclosing the statements between opening and 
      closing curly braces.

(*) Once a block of code has been created, it becomes a logical unit that can be used 
      any place that a single statement can.

      For example :-  A block can be target for Java's if and for statements. Consider 
                                 this if statement :

      if ( x < y )   {   // begin a block
            x = y ;
            y = 0 ;
     }  // end of block


     @) Here, if x is less than y, then both statements inside the block will be executed.
           Thus, the 2 statements inside the block form a logical unit, and 1 statement
           cannot execute without the other also executing.

     @) The key point here is that whenever you need to logically link two or more
            statements, you do so by creating a block.



(*) Let's look at another example. The following program uses a block of code as the 
      target of a for loop.

      /*
         Demonstrate a block of code.

         Call this file " BlockTest. java "
     */
      class BlockTest  {
          public static void main ( String args [ ] )    {
             int x,  y ;

             y = 20 ;

       // the target of this loop is a block

       for ( x = 0; x < 10;  x++ )     {
           System.out.println ( " This is x: " + x );
           System.out.println ( " This is y :" + y );
           y = y - 2;
         }
        }
      }


(*) Output :- This is x : 0
                       This is y : 20
                       This is x : 1
                       This is y : 18
                       This is x : 2
                       This is y : 16
                       This is x : 3
                       This is y : 14
                       This is x : 4
                       This is y : 12
                       This is x : 5
                       This is y : 10
                       This is x : 6
                       This is y : 8
                       This is x : 7
                       This is y : 6
                       This is x : 8
                       This is y : 4
                       This is x : 9
                       This is y : 2


     @) In this case, the target of the for loop is a block of code and not just a single 
           statement. Thus, each time the loop iterates, the three statements inside the 
           block will be executed.