How can I define an infinite loop condition in the for loop in java?

Question

I was making a program in which user can keep entering numbers till user enters a multiple of 10. So I wanted to created a for loop for that and didn't knew what should be the infinite loop condition for it.

Scanner sc = new Scanner(System.in);

int n;

for(int i = 1;true;i++) {
  n = sc.nextInt();
  if (n % 10 == 0) {
    break;
  }
}
System.out.println("Wake up to reality !");

You don't need a for loop. Just use while(true) {...}

Tangentially Perpendicular
– Tangentially Perpendicular

2025-04-15 08:14:17 +00:00
Commented Apr 15 at 8:14 — Tangentially Perpendicular
– Tangentially Perpendicular, Commented Apr 15 at 8:14

Mureinik · Accepted Answer · 2025-04-15 09:53:15Z

8

To create an infinite loop using a for loop, you can simply omit the condition altogether. In fact, you can omit any (or all) the elements in the for loop's parentheses:

for(;;) {
    n = sc.nextInt();
    if (n % 10 == 0) {
        break;
    }
}

Having said that, the idiomatic way of creating an infinite loop is with a while loop. Note that for a while loop you can't just omit the condition, but must explxicity state a boolean expression that evaluates to true. The simplest way to do this, is, of course, to use the boolean literal true:

while (true) {
    n = sc.nextInt();
    if (n % 10 == 0) {
        break;
    }
}

However, for this usecase, IMHO it would be more readable to use a do-while loop. This way you're garunteed that the loop runs at least once, and the exit condition is part of the loop and easy (easier?) to notice:

do {
    n = sc.nextInt();
} while (n % 10 != 0);

edited Apr 15 at 9:53

answered Apr 15 at 8:13

Mureinik

316k54 gold badges398 silver badges405 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

gthanop Apr 15 at 8:31

Great, but just a minor comment: I think the OP's question is "what should be the infinite loop condition" and I don't see this explicitly addressed here, hence the comment. It may be obvious to someone that the OP's condition is correct, but this doesn't seem the case for OP themselves. Can you please add such a statement? I believe such a clarification would help. Thank you in advance.

Mureinik Apr 15 at 9:53

@gthanop fair point, thanks! I edited my answer to clarify that.

gthanop Apr 15 at 10:18

Oh, I actually interpreted the infinite loop condition as the n % 10 == 0 check, ie the condition which terminates the infinite loop (so I expected a statement like "condition n % 10 == 0 is correct" or something). But I see now your point, which is that OP means the condition of the for loop, ie the one which gets the loop going. Excuse me, I got confused initially.

Collectives™ on Stack Overflow

How can I define an infinite loop condition in the for loop in java?

1 Answer 1

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related