Scope class demonstrates field and local variable scopes : Class Fields « Class Definition « Java Tutorial

1. Java Tutorial
2. Class Definition
3. Class Fields

public class MainClass
{
   public static void main( String args[] )
   {
      Scope testScope = new Scope();
      testScope.begin();
   }
}
class Scope
{
   private int x = 1; 

   public void begin()
   {
      int x = 5; // method's local variable x shadows field x

      System.out.printf( "local x in method begin is %d\n", x );

      useLocalVariable();
      useField();
      useLocalVariable();
      useField();

      System.out.printf( "\nlocal x in method begin is %d\n", x );
   }

   public void useLocalVariable()
   {
      int x = 25; // initialized each time useLocalVariable is called

      System.out.printf("\nlocal x on entering method useLocalVariable is %d\n", x );
      ++x; // modifies this method's local variable x
      System.out.printf( 
         "local x before exiting method useLocalVariable is %d\n", x );
   }

   // modify class Scope's field x during each call
   public void useField()
   {
      System.out.printf("\nfield x on entering method useField is %d\n", x );
      x *= 10; // modifies class Scope's field x
      System.out.printf("field x before exiting method useField is %d\n", x );
   }
}

local x in method begin is 5

local x on entering method useLocalVariable is 25
local x before exiting method useLocalVariable is 26

field x on entering method useField is 1
field x before exiting method useField is 10

local x on entering method useLocalVariable is 25
local x before exiting method useLocalVariable is 26

field x on entering method useField is 10
field x before exiting method useField is 100

local x in method begin is 5