Java While Loop

Loops

Loops can execute a block of code as long as a specified condition is true.

Loops are handy because they save time, reduce errors, and they make code more readable.

Java While Loop

The while loop repeats a block of code as long as the specified condition is true:

while (condition) {
  // code block to be executed
}

In the example below, the code in the loop will run again and again, as long as a variable (i) is less than 5:

int i = 0;
while (i < 5) {
  System.out.println(i);
  i++;
}

Countdown Example

You can also use a while loop to count down. This example counts from 3 to 1, and then prints "Happy New Year!!" at the end:

int countdown = 3;

while (countdown > 0) {
  System.out.println(countdown);
  countdown--;
}

System.out.println("Happy New Year!!");

While Loop With False Condition

In the previous examples, the condition was true at the start, so the loop ran one or more times. But if the condition is false at the beginning, the code inside the loop will never run:

int i = 10;

while (i < 5) {
  System.out.println("This will never be printed");
}