The dangling-else problem:

The Java compiler always associates an else with the immediately preceding if unless told to do otherwise by the placement of braces ({ and }).

if ( x > 5 )
   if ( y > 5 )
     System.out.println( "x and y are > 5" );
 else
    System.out.println( "x is <= 5" );

 

 if ( x > 5 )
   if ( y > 5 )
     System.out.println( "x and y are > 5" );
   else
      System.out.println( "x is <= 5" );

 
Case I Case II
if ( x > 5 )
{
  if ( y > 5 )
    System.out.println( "x and y are > 5" );
}
 else
    System.out.println( "x is <= 5" );

 

 Note that:  Case I same as Case II.  Case III is different from Case I & Case II.
Case III  

Exercise 4.27 on page 152-153:

Determine the output for each the given sets of code when x is 9 and y is 11 and when x is 11 and y is 9.

                       

Statements contained in a pair of braces form a block.

Example:

	if ( grade >= 60 )
             System.out.println("Passed");
        else 
         {   
             System.out.println("Failed");
             System.out.println("You must take this course again.");
         }

What happen if there is no braces?