JavaVisibility

From JavaProgramming.

Visibility of class members is almost the same as in C++, with a couple of important exceptions:

Default (no visibility specified)

• Not visible outside the class, except for classes in the same package
• Not visible from subclasses

Private

• Not visible outside the class
• Not visible from subclasses

Protected

• Not visible outside the class, except for classes in the same package
• Visible from subclasses

Public

• Visible outside the class
• Visible from subclasses

Here is a test program to demonstrate visibility:

 /* TestVisibility.java */
 class Classname {
   int defaultVar;
   public int publicVar;
   protected int protectedVar;
   private int privateVar;
 }

 public class TestVisibility {
   public static void main(String[] args) {
     Classname foo = new Classname();
     foo.defaultVar++;    // Visible within the package
     foo.publicVar++;     // Evidently public visibility
     foo.protectedVar++;  // Visible within the package!!!
     foo.privateVar++;    // Compiler error: privateVar has private access 
   }
 }