In this java programming tutorial, you will learn access modifiers in java, how to use default access modifier in java, how to use private modifier in java, how to use protected modifier in java and public modifier in java with examples.
Access Modifiers
- It is mainly used to decide the scope of various programming elements such as variables, functions, constructor, destructor, etc, ..
- It gives the scope and lifetime to object properties (instance variables & functions) and class properties (static variables & functions)
- It is used to access the state (Ex. variable) and behavior (Ex. function) of objects / class
- It is used to set the access privilege levels to members of a class (e.g. variables/functions)
- Java supports four different types of modifiers. They are:
- Private
- Public
- Protected
- Default / No Modifier / Package Private (Default for variables / methods / constructors / classes)
Usage
- It is used to implement the important feature of oops called data hiding.
GENERAL SYNTAX OF ACCESS MODIFIERS
class <name>
{
private members; (variables & methods)
public members: (variables & methods)
protected members; (variables & methods)
default members; (variables & methods)
}
Example
1. PRIVATE MODIFIER
- It is accessible only within a same class (current class) of same package
- Private data can’t be accessible in outside of a class or other packages
- It gives more security than other modifiers
Usage
- It is used to implement the concept of data hiding (information hiding) feature.
Syntax
Example
1. EXAMPLE OF PRIVATE MODIFIER
(JPrivateM.java)
SOURCE CODE
public class JPrivateM
{
// private variable definition
private int k=10;
public void disp()
{
System.out.println(“k= “+k);
}
public static void main(String[] args)
{
System.out.println(“——————————-“);
System.out.println(“\tPrivate Modifier”);
System.out.println(“——————————-“);
// object creation
JPrivateM obj=new JPrivateM();
// calling instance method using object
obj.disp();
}
}
OUTPUT
DRAWBACKS
- It is not possible to access the private variables outside of a class.
2. PUBLIC MODIFIER
- It is accessible anywhere in the programming
- Most accessible modifier (recommended modifier)
- Public data can be accessible in outside of a class / main function / derived class (if inheritance involved)
- It does not provide security than other modifiers
Syntax
Example
2. EXAMPLE OF PUBLIC MODIFIER
(JPublicM.java)
SOURCE CODE
public class JPublicM
{
// public variables definition
public String name=”Rohit”;
public int id=73;
void disp()
{
System.out.println(“Name \t”+name);
System.out.println(“Id \t”+id);
}
public static void main(String[] args)
{
System.out.println(“———————————“);
System.out.println(“\tPublic Modifier”);
System.out.println(“———————————“);
// object creation
JPublicM obj=new JPublicM();
// calling instance method using object
obj.disp();
}
}
OUTPUT
3. PROTECTED MODIFIER
- It is similar to private modifier
- It is accessible anywhere within a same package (current class or subclass or other classes in same package) as well as in derived class in other package (If inheritance is involved)
- Protected data can’t accessible in other class in other package
Syntax
Example
3. EXAMPLE OF PROTECTED MODIFIER
(JProtectedM.java)
SOURCE CODE
public class JProtectedM
{
// protected variable definition
protected int k=25;
public void disp()
{
System.out.println(“k= “+k);
}
public static void main(String[] args)
{
System.out.println(“—————————————————————“);
System.out.println(“\tProtected Modifier”);
System.out.println(“—————————————————————“);
// object creation for current class
JProtectedM obj=new JProtectedM();
// calling instance method using object
obj.disp();
}
}
OUTPUT
DRAWBACKS
- It is not possible to access the protected variables in other classes of other packages except sub-class (derived class) in other packages.
4. DEFAULT (PACKAGE PRIVATE | FRIENDLY)
- It is the default modifier in java and its scope is limited to current package only
- If we don’t mention any modifier, then system will treat it as a default modifier (no modifier / package private)
- It can be accessible anywhere in the same / current package. But outside of the package is not possible.
Syntax
Example
4. EXAMPLE OF PACKAGE PRIVATE MODIFIER
(JProtectedM.java)
SOURCE CODE
public class JPackagePrivateM
{
// package private (friendly) variable definition
int n=111;
String name=”Sachin”;
// package private (friendly) method implementation
void info()
{
System.out.println(“Name \t: “+name);
System.out.println(“Number \t: “+n);
}
public static void main(String[] args)
{
System.out.println(“——————————–“);
System.out.println(“\tFriendly Modifier”);
System.out.println(“——————————–“);
// object creation
JPackagePrivateM obj=new JPackagePrivateM();
// calling instance method using object
obj.info();
}
}
OUTPUT
NOTE
- All the variables and methods of a class are package private by default. (If no access modifier is specified)
SUMMARY
| S.N | MODIFIERS | PURPOSE |
| 1. | Private | It is accessible only within a class of same package |
| 2. | Protected | It is accessible only within a class as well as derived class |
| 3. | Public | It is accessible anywhere in the programming (including same / other packages) |
| 4. | Package Private | It is accessible anywhere in the same packageDefault modifier |
Default Access Modifiers
Variables – default modifier by default
Methods, Constructors – default modifier by default
Class – default modifier by default
Class Modifier
- In java, the default modifier of class is default modifier
- Class does not support private and protected modifiers. It supports only public and default modifiers.