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I'm working on a golf for Java and I need an infinite loop. Obviously, I don't want to spend any more bytes than I have to, especially in such an expressive language.

Assuming I have some code I want to run, obviously the baseline is set at while(1>0)/*stmt*/ or 10 additional characters for a single line and while(1>0){/*stmt1*//*stmt2*/} or 12 additional characters for multiple lines. I say additional because the code I want to loop forever (well, forever-ish... I may or may not want to break out of or return from the loop) will have a certain length, and then I must tack on additional characters to make it actually loop.

At first I thought this was the best I'd get, but I figured I'd throw it out to the experts to see if they can find a better one.

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  • \$\begingroup\$ Or something like main();? \$\endgroup\$
    – jimmy23013
    Sep 2, 2015 at 18:08
  • \$\begingroup\$ @jimmy23013 No, but you can do main(null). \$\endgroup\$
    – Ypnypn
    Sep 2, 2015 at 18:14
  • \$\begingroup\$ @Ypnypn Or main(a) if main is declared as public static void main(String[]a). \$\endgroup\$
    – Dennis
    Sep 2, 2015 at 18:15
  • \$\begingroup\$ Out of interest do Java compilers or JITs typically optimize tail-call recursion, or are these recursions limited by stack size? \$\endgroup\$
    – Steve Jessop
    Sep 2, 2015 at 23:39
  • \$\begingroup\$ Related: codegolf.stackexchange.com/questions/13152/… \$\endgroup\$
    – Kzqai
    Sep 3, 2015 at 0:24

4 Answers 4

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for(;;){}

It works cause no condition evaluates to always true. Insert the code between the braces.

If you only got a few statements you can place them inside the head (the (;;) part. That the loop still runs is caused by when the condition statement is not a boolean it counts as always true. Thanx to @Ypnypn for the reminder

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    \$\begingroup\$ If you have multiple statements, try to put all but one in the for loop itself. e.g., for(;;foo(),bar(),baz())quux(); \$\endgroup\$
    – Ypnypn
    Sep 2, 2015 at 18:14
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    \$\begingroup\$ you can exchange the empty braces for a semicolon for(;;); \$\endgroup\$
    – ratchet freak
    Sep 2, 2015 at 22:35
  • \$\begingroup\$ @ratchetfreak Only if you don't intend to break the loop, but the OP that they do want the ability to break. \$\endgroup\$
    – Alex A.
    Sep 3, 2015 at 0:14
  • \$\begingroup\$ @ratchetfreak Yes I'm looking for both single and multi-line, although it's debatable whether Ypnypn's suggestion might actually be smaller. Either way, I should edit my post to make my objective more clear. \$\endgroup\$
    – corsiKa
    Sep 3, 2015 at 2:07
  • \$\begingroup\$ @Ypnypn I don't think that's legal syntax. There's no comma operator in Java (though it can be used in variable declarations). \$\endgroup\$
    – Tom Hawtin - tackline
    Oct 6, 2018 at 23:19
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50 bytes

interface M{static void main(String[]a){for(;;);}}
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Java - 60 bytes (complete code)

I'm probably not interpreting the question correctly, but this code when compiled and run results in an infinite-ish loop, in that technically it should run forever, but usually it will exhaust the stack memory.

public class X{public static void main(String[]a){main(a);}}

On Coding Ground it ends quite quickly, on my Windows 7 laptop with advanced virtual memory management, it runs a long time, just making the system slower and slower.

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    \$\begingroup\$ problem with your solution is, it will give you quite quickly StackOverflowError so it hard to call it infinite loop \$\endgroup\$
    – user902383
    Feb 12, 2016 at 11:10
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for(/*init*/;;/*stmt*/){/*stmt*/}

To save characters, you can use the init and increment parts of the loop to save a few bytes by using the semicolons.

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  • \$\begingroup\$ How is this different than the accepted answer? \$\endgroup\$
    – corsiKa
    Jun 27, 2022 at 2:25
  • \$\begingroup\$ I'm just trying to make it more clear where the statements should go. One more thing: If you do need to use break, you can put it in the condition. \$\endgroup\$
    – Eric Xue
    Jul 2, 2022 at 15:32

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