Question

Possible Duplicate:
Variable scope in a switch case

I’ve got a code like this:

switch(a) {
case b:
 Object o = new Object();
 return o;
case c:
 o = new Object();
 return o;
 }

and i’m interesting why it’s possible to use variable declared after first case label in the second one even if first state will never be reached?

Answer 1

Despite being in different cases, the variables local to the switch statement are in the same block, which means they are in the same scope.

As far as I know, new scope in Java is only created in a new block of code. A block of code (with more than one line) has to be surrounded by curly braces. The code in the cases of a switch statement is not surrounded by curly braces, so it is part of the whole statement’s scope.

However, you can actually introduce a new scope to the statement by adding curly braces:

switch (cond) {
case 1:{
     Object o = new Object();
}
    break;
case 2:{
    // Object o is not defined here!
}
    break;
}