Java switch : variable declaration and scope

Question

How does the Java compiler handle the following switch block ? What is the scope of the \'b\' variable ?

Note that the \'b\' variable is declared only in the first b

Answer 1

The scope of b is the switch block - between the declaration and the delimiter } -

int a = 3;

switch( a ) {
     case 0:
          int b = 1; //scope starts
          System.out.println("case 0: b = " + b);
          break;
     case 1:
          // the following line does not compile: b may not have been initialized
          // System.out.println("case 1 before: b = " + b);
          b = 2;
          System.out.println("case 1 after: b = " + b);
          break;
     default:
          b = 7;
          System.out.println("default: b = " + b);
}//scope ends

However, you need to know that if you declare the int b inside the case 1:, you will NOT have access to the variable b inside the case 0:

To answer the question you ask in the java comments you can check this simpler example:

int b;
if(true){
    b++; //The local variable b hast not been initialized
}

Hope it helps.