Counter-Controlled Repetition
Click while / for to see the concepts.

Counter-controlled repetition requires

// Fig. 5.1:
// Counter-controlled repetition with the while repetition statement.

public class WhileCounter 
   public static void main( String[] args ) 
      int counter = 1; // declare and initialize control variable

      while ( counter <= 10 ) // loop-continuation condition
         System.out.printf( "%d  ", counter );
         ++counter; // increment control variable by 1
      } // end while

      System.out.println(); // output a newline
   } // end main
} // end class WhileCounter

for repetition statement

// Fig. 5.2:
// Counter-controlled repetition with the for repetition statement.

public class ForCounter 
   public static void main( String[] args ) 
      // for statement header includes initialization,  
      // loop-continuation condition and increment
      for ( int counter = 1; counter <= 10; counter++ ) 
         System.out.printf( "%d  ", counter );

      System.out.println(); // output a newline
   } // end main
} // end class ForCounter

A common logic error with counter-controlled repetition is an off-by-one error. 
For example, if the above condition is changed to counter < 10, the loop would iterate only nine times.

The general format of the for statement is

for ( initialization; loopContinuationCondition; increment )

In most cases, the for statement can be represented with an equivalent while statement as follows:

while ( loopContinuationCondition )

Typically, for statements are used for counter-controlled repetition and while statements for sentinel-controlled repetition.

If the initialization expression in the for header declares the control variable, the control variable can be used only in that for statement.

A variable’s scope defines where it can be used in a program.
A local variable can be used only in the method that declares it and only from the point of declaration through the end of the method.

The increment expression in a for acts as if it were a standalone statement at the end of the for’s body, so

counter = counter + 1
counter += 1

are equivalent increment expressions in a for statement.

Assume that x = 2 and y = 10. If x and y are not modified in the body of the loop, the statement

for (int j = x; j <= 4 * x * y; j += y / x)

is equivalent to the statement

for (int j = 2; j <= 80; j += 5)