Unreachable code error vs. dead code warning in Java under Eclipse?

Question

Does anyone know why:

public void foo()
{
    System.out.println(\"Hello\");
    return;
    System.out.println(\"World!\");
}

Would be rep

Answer 1

This is to allow a kind of conditionally compilation.
It is not an error with if, but the compiler will flag an error for while, do-while and for.
This is OK:

if (true) return;    // or false
System.out.println("doing something");

This are errors

while (true) {
}
System.out.println("unreachable");

while (false) {
    System.out.println("unreachable");
}

do {
} while (true);
System.out.println("unreachable");

for(;;) {
}
System.out.println("unreachable");

---

It is explained at the end of JLS 14.21: Unreachable Statements:

The rationale for this differing treatment is to allow programmers to define "flag variables" such as:

 static final boolean DEBUG = false;

and then write code such as:

   if (DEBUG) { x=3; }

The idea is that it should be possible to change the value of DEBUG from false to true or from true to false and then compile the code correctly with no other changes to the program text.