Access Modifiers In Java

Introduction

1. Private
2. Protected
3. Public

Java Access Modifier - Private Keyword

• Private Method
  
  If a method marked as private, it cannot be invoked from outside the class it is declared. In other words, the private method is available to the enclosing class. For example:
  
  1. class A
  2. {
  3. private void foo()
  4. {
  5. }
  6. void bar()
  7. {
  8. foo(); // okay, no problem!
  9. }
  10. }
  11. class B
  12. {
  13. void woo()
  14. {
  15. A a = new A();
  16. a.foo(); // Oh no! since foo() is private
  17. }
  18. }
• Private Variable
  
  The private access modifier can also be applied to member variables which are declared within a class. Like private method, a private variable can be accessed only within its enclosing class. For example:
  
  1. class A
  2. {
  3. private int number;
  5. void bar()
  6. {
  7. number = 10; // OK
  8. }
  9. }
  11. class B
  12. {
  13. void foo()
  14. {
  15. A a = new A();
  16. a.number = 10. // Oh no! since number is private
  17. }
  18. }
• Private inner class
  
  An inner class is one that is declared inside another class. An inner class can be declared as private thus it can be accessed only from within the enclosing class, like private method and private variable. For example:
  
  1. class A {
  2. private class SubA {
  3. // inner class
  4. }
  5. void bar() {
  6. SubA obj = new SubA(); // OK
  7. }
  8. }
  10. class B {
  11. void foo() {
  12. A.SubA a = new A.SubA(); // Oh no! since SubA is private
  13. }
  14. }