Java Inner Class
Java inner class or nested class is a class
Eg. declared inside the class or interface.
We
use inner classes to logically group classes and interfaces in one place so
that it can be more readable and maintainable.
Additionally,
it can access all the members of outer class including private data members and
methods.
Syntax of Inner class
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1.
2.
class Java_Outer_class{
3.
//code
4.
class Java_Inner_class{
5.
//code
6.
}
7.
}
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Advantage of java inner classes
There
are basically three advantages of inner classes in java. They are as follows:
1)
Nested classes represent a special type of relationship that is it can access all the members (data members and
methods) of outer class including
private.
2)
Nested classes are used to develop
more readable and maintainable code because it logically group classes and interfaces in
one place only.
3) Code Optimization: It requires less code to write.
Difference between nested class and inner
class in Java
Inner
class is a part of nested class. Non-static nested classes are known as inner
classes.
Types of Nested classes
There are two types of nested
classes non-static and static nested classes.The non-static nested classes are
also known as inner classes.
1.
Non-static
nested class(inner class)
o
a)Member
inner class
o
b)Anonymous
inner class
o
c)Local
inner class
2.
Static
nested class
Java Local inner class
A
class i.e. created inside a method is called local inner class in java. If you
want to invoke the methods of local inner class, you must instantiate this
class inside the method.
Java local inner class example
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1.
2.
public class localInner1{
3.
private int data=30;//instance variable
4.
void display(){
5.
class Local{
6.
void msg(){System.out.println(data);}
7.
}
8.
Local l=new Local();
9.
l.msg();
10.
}
11.
public static void main(String args[]){
12.
localInner1 obj=new localInner1();
13.
obj.display();
14.
}
15.
}
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Output:
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30
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