/** This program demonstrates some basic features of scope. Scope defines

 *  the region in a program where a variable exists and can be used.

 *

 *  @author TK Rogers

 *  @version 10-26-10 */

public class ScopeDemo {

   private int x = 2; // Creates a field called x with a scope inside the

                            // ScopeDemo class.

   public static void main ( ) {

       ScopeDemo s = new ScopeDemo ( ); // Creates a local instance with a      

                                                                // scope inside main.

       int x = 12; // Creates a local variable called x with a scope inside main

       System.out.println ( "In main instance x = " + s.x + "  local main x = " + x );

       s.alter ( );

       s.x = 23;

       s.alter ( );

       System.out.println ( "In main instance x = " + s.x + "  local main x = " + x );
 

       { // This pair of brackets could be attached to a statement such as a 

         // for-loop or if statement. Any variable created here will only have 

         // a scope inside the brackets.

           int z = 500; // Creates a local variable called z with a scope inside the { }

           System.out.println ( "In main instance {z} = " + z );

       } // At this point the variable z ceases to exist.

      

       // Try uncommenting the line shown below and the program

 //  will not compile. Why?

       // System.out.println ( "In main instance z = " + z );

   }

  

   public void alter ( ) {  

       System.out.print ( "In alter instance x = " + x );

       int x = 70; // Creates a local variable called x with a scope inside alter

       System.out.println ( "  local alter x = " + x );

      

       // Try uncommenting the line shown below and the program

 // will not compile. Why?

       // System.out.print ( "instance x = " + s.x );

   }

}