Why Java’s for(;;) and while(true) Loops Have No Performance Difference

By searching the JDK8u source tree the author found 369 occurrences of for (;;) and 323 occurrences of while (true) , indicating both patterns are widely used.

The for (;;) syntax is inherited from C, where the loop header can omit the initialization, condition, and update expressions; using it to express an infinite loop avoids writing a magic constant like 1 in while (1) . Some developers still prefer while (true) , but both are functionally equivalent.

To compare their performance the author compiled two methods with javac (Oracle/Sun JDK8u / OpenJDK8u) and examined the generated bytecode.

Method using while (true) :

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

Method using for (;;) :

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

Both methods produced identical bytecode (stack=1, locals=2, args_size=1):

0: iconst_0
1: istore_1
2: iinc 1, 1
5: goto 2

Since the Java compiler performs only minimal optimizations and generates the same bytecode for both loops, there is no performance difference at the bytecode level; any further differences would depend on the JVM’s JIT compiler, which sees identical input.

Thus, the choice between for (;;) and while (true) is a matter of style rather than efficiency.