Why Does Java’s for(;;) Loop Exist and Is It Faster Than while(true)?

Searching the JDK8u source tree shows roughly the same number of infinite loops written as for(;;) and while(true) (369 vs 323 occurrences).

The for(;;) syntax in Java traces back to C, where developers used it to avoid writing a literal constant such as while(1). It provides a clear way to express an infinite loop without a “magic number”.

In C, without including certain headers, there is no built‑in bool type, so while(1) was common, but many preferred for(;;) for readability.

In Java the author prefers while(true), though for(;;) is also acceptable.

Which is faster in Java, for(;;) or while(true) ?

The Java language specification does not dictate performance; it depends on the implementation. Compiling both versions with javac (Oracle/Sun JDK8u / OpenJDK8u) yields identical bytecode, as shown below.

public void foo() {
    int i = 0;
    while (true) { i++; }
}

/* Bytecode:
   0: iconst_0
   1: istore_1
   2: iinc 1, 1
   5: goto 2
*/

public void bar() {
    int i = 0;
    for (;;) { i++; }
}

/* Bytecode:
   0: iconst_0
   1: istore_1
   2: iinc 1, 1
   5: goto 2
*/

Since the generated bytecode is identical, any performance difference would only arise later during interpretation or JIT compilation, where the input is the same, so the output is effectively identical.