Duplicate local variable in switch statement [duplicate]

Question

I was getting this error using Eclipse.

Duplicate local variable cape

I really don't understand why I was getting such an error. This was my code:

switch (frame) {  // frame is an integer
case 0:
    Sprite cape = modules.get(Module.CAPE);
    //cape.setRegion(region);
    cape.translateY(+1);
    break;
case 1:
    Sprite cape = modules.get(Module.CAPE);
    //cape.setRegion(region);
    cape.translateY(-1);
    break;
default:
    throw new IllegalArgumentException(
            "Undefined frame number: " + frame);
}

Why is it not true that the cape variable is local to each case, but instead to the switch statement?

Answer 1

The whole switch statement is a code block like any other. But you can create code blocks inside code blocks, so:

case 0: {
    // code here
}
case 1: {
    // other code here
}

(if the switch were treated specially in this regard you couldn't be able to do follow through)

Answer 2

Each case is within the same block, specifically, the {} for the switch statement. This is the same block even when different cases define the same variable.

Define your own blocks for each case by adding {}s:

case 0:
  {
    Sprite cape = modules.get(Module.CAPE);
    //cape.setRegion(region);
    cape.translateY(+1);
  }
    break;
case 1:
  {
    Sprite cape = modules.get(Module.CAPE);
    //cape.setRegion(region);
    cape.translateY(-1);
  }
    break;

Or you can simply declare cape before the switch so it's in scope there, where you use the reference.

Sprite cape;
switch (frame) {  // frame is an integer
case 0:
    cape = modules.get(Module.CAPE);

and similarly for case 1.