int counter=0;

while ( counter < 10 )
{
  System.out.println("counter is now " + counter );
  counter++ ;
}

Increment Operator

The increment operator ++ adds one to a variable. Usually the variable is an integer type (byte, short, int, or long) but it can be a floating point type (float or double.) No character is allowed between the two plus signs. Usually the plus signs are put immediately adjacent to the variable, as above, although this is not necessary.

The increment operator can be used as part of an arithmetic expression, as in the following:

int sum = 0;
int counter = 10;

sum = counter++ ;

System.out.println("sum: "+ sum " + counter: " + counter );

Here is how the statement sum = counter++; works: In the statement sum = counter++; the variable counter is incremented after the value it holds has been used. It is vital to understand the details of this:

• The assignment statement is executed in two steps:
  1. Evaluate the expression on the right of the =
     • the value is 10 (because counter has not been incremented yet.)
  2. Assign the value to the variable on the left of the =
     • sum gets 10.
• Now the ++ operator works: counter is incremented to 11.
• The next statement writes out: sum: 10 counter: 11

int x = 99;
int y = 10;

y = x++ ;

System.out.println("x: " + x + "  y: " + y );