#DEAD CODE JAVA FOR LOOP CODE#

In fact, Eclipse does even more advanced tests to determine the possible values for an if statement to determine whether or not it is possible to take both paths. There may be language-specific subtleties at work that prevent elimination of apparently dead code. You might be able to add a clever AI that will be able to find a loop through some cleverness in some cases, but it wont work in all cases. If you never enter two identical states, which could happen for an infinite Turing machine, then you dont know whether you are in a cycle.

#DEAD CODE JAVA FOR LOOP CODE#

This second block is a 'code smell', if (false) blocks are normally put in to disable code for debugging purposes, having it left behind is typically accidental, and hence the warning. If you enter two identical states, then you are in a loop. Code reordering, splitting, and removal Loop reduction and inversion. This is entirely optional, and, by using the Eclipse configuration, can be disabled, or turned into a compiler error instead of a warning. Using multiple threads can potentially help Java applications to start faster. This is an additional lint style check that Eclipse provides. The second warning that Eclipse gives, about dead code, is a warning generated by the compiler, that is not 'unreachable', according to the JLS, but in practice is. An optimizing compiler may realize that the statement x=3 will never be executed and may choose to omit the code for that statement from the generated class file, but the statement x=3 is not regarded as 'unreachable' in the technical sense specified here. public class Test ĭoes not result in a compile-time error. Update: the JDK actually eliminates dead code. That's the difference.Īs to why Eclipse detects dead code, well, that's just the convenience of an integrated development tool with a built-in compiler which can be finetuned more as opposed to JDK to detect this kind of code. This, i++ will never get a chance to run and thus, it is a dead code. It may be some condition, loop or any file which was simply created but wasnt used in your project. The first does not compile (you got an error), the second compiles (you just got a warning). Also, why is this code a dead code When your loop runs for i 3, it will be terminated by break statement. Dead code is any code which will never be executed. Wouldn't the Java compiler then apply its reachable code analysis again? I guess a more general way to think of this question is: 'when is the reachable code analysis applied'? In the transformation of the second Java code fragment to the final bytecode, I am sure that at some point the 'if(true)' runtime equivalent is removed, and the representations of the two programs become identical. Wouldn't the Java compiler figure out at compile time that the if(true) has no effect, thus yielding bytecode that is essentially identical? At what point is the reachable code analysis applied?

However, if that is the case, why can't the Java compiler figure out this case at compile time? The only explanation I can think of is that the Java compiler only flags the first, and that some extra analysis in Eclipse figures out the second.

Would be reported as an 'unreachable error' under Eclipse, but public void foo()

Dead code java for loop