“loop:” in Java code. What is this, and why does it compile?

Question

This code just made me stare at my screen for a few minutes:

loop:
for (;;) {
    // ...
}

(line 137 here)

I have never seen this b

Answer 1

As other posters have said, it is a label, not a keyword. Using labels allows you to do things like:

outer: for(;;) {
   inner: for(;;) {
     break outer;
   }
}

This allows for breaking of the outer loop.

Link to documentation.