Java: for(;;) vs. while(true)

Posted 2020-08-05 沧海一滴

What is the difference between a standard while(true) loop and for(;;)?

Is there any, or will both be mapped to the same bytecode after compiling?

Semantically, they‘re completely equivalent. It‘s a matter of taste, but I think while(true) looks cleaner, and is easier to read and understand at first glance. In Java neither of them causes compiler warnings.

At the bytecode level, it might depend on the compiler and the level of optimizations, but in principle the code emitted should be the same.

EDIT:

On my compiler, using the Bytecode Outline plugin,the bytecode for for(;;){} looks like this:

   L0
    LINENUMBER 6 L0
   FRAME SAME
    GOTO L0

And the bytecode for while(true){} looks like this:

   L0
    LINENUMBER 6 L0
   FRAME SAME
    GOTO L0

So yes, at least for me, they‘re identical.

It‘s up to you which one to use. Cause they are equals to compiler.

public class Test {
    public static void main(String[] args) {
        while (true) {
            System.out.println("Hi");
        }
    }
}

javac -g:none Test.java
rename Test.class Test1.class

public class Test {
    public static void main(String[] args) {
        for (;;) {
            System.out.println("Hi");
        }
    }
}

# javac -g:none Test.java
# mv Test.class Test2.class
# diff -s Test1.class Test2.class
Files Test1.class and Test2.class are identical

http://stackoverflow.com/questions/8880870/java-for-vs-whiletrue