What are inner classes and its types ?

Answer 1

In Java, it is also possible to nest classes (a class within a class). The purpose of nested classes is to group classes that belong together, which makes your code more readable and maintainable.
To access the inner class, create an object of the outer class, and then create an object of the inner class:
Example:
class OuterClass {
int x = 10;
class InnerClass { int y = 5; } }

public class Main { public static void main(String[] args){
OuterClass myOuter = new OuterClass(); OuterClass.InnerClass myInner = myOuter.new InnerClass(); System.out.println(myInner.y + myOuter.x); } }
// Outputs 15 (5 + 10)

Unlike a "regular" class, an inner class can be private or protected. If you don't want outside objects to access the inner class, declare the class as private.

Answer 2

Thanks