Java Do/While Loop
The Do/While Loop
The do/while
loop is a variant of the while
loop. This loop will
execute the code block once, before checking if the condition is true.
Then it will
repeat the loop as long as the condition is true.
Syntax
do {
// code block to be executed
}
while (condition);
Note: The semicolon ;
after the while
condition is required!
Do/While Example
The example below uses a do/while
loop. The loop will always be
executed at least once, even if the condition is false, because the code block
is executed before the condition is tested:
Do not forget to increase the variable used in the condition (i++
), otherwise
the loop will never end!
Condition is False from the Start
In the example above, the condition i < 5
was
true at the beginning, so the loop executed multiple times. But what if the condition is
false right from the start?
In the example below, the variable i
starts at 10, so the condition i < 5
is false immediately
- yet the do/while
loop still runs once:
Summary: The do/while
loop always runs at least once, even if the condition is already false. This is different from a regular while
loop, which would skip the loop entirely if the condition is false at the start.
This behavior makes do/while
useful when you want to ensure something happens at least once, like showing a message or asking for user input.