Java public,default,private &protected modifiers
1. public members:-
If a member(variable or method) declared as public then we can access that member from anywhere.
But corresponding class should be visible or accessible so that before checking member visibility we have to check class visibility.
example:-
In the above example m1() method is public but we can't access from outside package corresponding class A is not public i.e. if both classes & method are public than only we can access the method from outside package.
2.default members:-
If a member declared as default then we can access that member only within the current package i.e. from outside of the package we can't access.
Hence default access is also known as package level access.
3.private members:-
- If a member is private then we can access that member only within the class i.e. from outside of the class we can't access.
- abstract methods should be available to the child classes to provide implementation, whereas private methods are not available to the child classes to provide the implementation. Hence private abstract combination is illegal from methods.
4.protected members;-
- If a member declared as protected then we can access that member anywhere in the current package but only in child classes of outside package.
- We can access protected members within the current package anywhere either by using its or by using child reference but we can access protected members in outside package only in child classes and we should use "child reference only".i.e. parent reference cannot be used to access protected members from outside package.
example 1. within the same package
package pack1;
public class A
{
protected void m1( )
{
System.out.println("protected member");
}
}
class B extends A
{
public static void main(String args[])
{
A a =new A( );
a.m1();
B b =new B( );
b.m1();
A a1 =new B( );
a1.m1();
}
}
javac -d. B.java
java pack1.B
Output:-
protected member
protected member
protected member
example 2. outside the package
package pack1;
public class A
{
protected void m1( )
{
System.out.println("protected member");
}
}
package pack2;
import pack1.A;
class C extends A
{
public static void main(String args[])
{
A a =new A( );
a.m1( ); Compile Time Error
m1( )has protected access in pack1.A
C c =new C( );
c.m1( ); valid o/p is: protected member
A a1 =new C ( );
a1.m1( ); Compile Time Error
} m1( )has protected access in pack1.A
}
- We can access protected members from outside package only in the child class and we should use that "child class reference only".
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