while Statement
A while
statement creates a loop that executes continuously as long as some conditional expression evaluates to true
. The basic syntax is this:
while (expression)
statement
The while
statement begins by evaluating the expression. If the expression is true
, statement
is executed. Then the expression is evaluated again, and the whole process repeats. If the expression is false
, statement
is not executed, and the while
loop ends.
Note: The statement part of the while
loop can either be a single statement or a block of statements contained in a pair of braces.
Here’s a snippet of code that uses a while
loop to print the even numbers from 2 through 20 on the console:
int number = 2;
while (number <= 20)
{
System.out.print(number + “ “);
number += 2;
}
If you run this code, the following output is displayed in the console window:
2 4 6 8 10 12 14 16 18 20
The conditional expression in this program’s while
statement is number
<=
20
. That means the loop repeats as long as the value of number
is less than or equal to 20
. The body of the loop consists of two statements. The first prints the value of number
, followed by a space to separate this number from the next one. Then the second statement adds 2 to number
.