Code block and scope

Braces is the code block

• With a name code blocks --if-else block, for loop code block, main code block method
• Also called code blocks, eg for body, the method main body
• Code blocks can be nested

Variable scope

• Code block where you can create and use variables
• Block can be used in the outer code block variable
• However, not using the inner code blocks in the variables in the outer code block. (Can use variables, also called a code block variable visibility. That is, the outer block of code creates a variable visible to the inner code blocks, a variable inner code blocks created in the outer layer does not block visible.)
• Namespace inner variable (or a scope) can not be repeated define variables outer code block, the outer code block may be used in
• No matter how many layers of nested code blocks, follow the above variables visibility rules.

Scopes and namespaces

• With a namespace variable can not be duplicate names
• In order to avoid conflict of variable names, so there must be a namespace

public  class codeblock {
     public  static  void main (String [] args) {
         // inner code block in the scope (namespace) can be used to block the external variables.
        // In turn, external variables can not be used to block scope.
        // scope of the code block with the end of execution of the code block ends. 
        int Outer = 100 ;
        {
            int inner = 10;
            System.out.println ( "outer value is" + outer + "inner value is." + Inner);
        }

        // block can be nested. The same life cycle rule scope. 
        int A1 =. 1 ;
        {
            int a2 = a1 + 1;
            {
                an int 3a , = A2 + 1 ;
                System.out.println("a3=" + a3);
            }
            {
                an int 3a , = A2 + 10 ;
                System.out.println("a3=" + a3);
            }
            System.out.println("a2=" + a2);
        }
    }
}