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Java modifiers

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Modifiers are keywords that you add to those definitions to change their meanings. Java language has a wide variety of modifiers.To use a modifier, you include its keyword in the definition of a class, method, or variable. The modifier precedes the rest of the statement.

There are 4 types of java access modifiers:

1.private
2.default
3.protected
4.public


1) private access modifier

The private access modifier is accessible only within class.

Example:

class A
{ 
   private int data=40;
   
   private void msg()
   {
       System.out.println("Hello java");
   }

}

public class Simple
{ 
   public static void main(String args[])
   {
      A obj=new A(); 
      System.out.println(obj.data);//Compile Time Error, data is private
   }
}

Output:

compile time error

Reason:  we have created two classes A and Simple. A class contains private data member and private method. We are accessing these private members from outside the class, so there is compile time error.


2) Default access modifier

If you don't use any modifier, it is treated as default by default. The default modifier is accessible only within package.


Example:

//save by A.java  
package pack;  
class A
{  
  void msg()
  {
    System.out.println("Hello");
  }  
}  

//save by B.java  
package mypack;  
import pack.*;  
class B
{  
  public static void main(String args[]) 
  {  
    A obj = new A();//Compile Time Error  
    obj.msg();//Compile Time Error  
  }  
}  
 

 Output:

compile time error

Reason:In the above example, the scope of class A and its method msg() is default so it cannot be accessed from outside the package.


3) protected access modifier

The protected access modifier is accessible within package and outside the package but through inheritance only.

The protected access modifier can be applied on the data member, method and constructor. It can't be applied on the class.


4) public access modifier

The public access modifier is accessible everywhere. It has the widest scope among all other modifiers.

Example:

//save by A.java  
package pack;  
public class A
{  
    public void msg()
    {
        System.out.println("Hello");
    }  
}  

//save by B.java    
package mypack;  
import pack.*;  
  
class B
{  
  public static void main(String args[])
  {  
    A obj = new A();  
    obj.msg();  
  }  
}  


Output:
Hello

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