Why inner class is used in Java?

I would declare inner-classes in the bottom of the file – usually you’re not interested in their implementations and just want to get to your main class’ methods, so they shouldn’t get in the way.

inner classes are in the same file, whereas subclasses can be in another file, maybe in another package . You cannot get an instance of an inner class without an instance of the class that contains it.

Creating an inner class is quite simple. You just need to write a class within a class . Unlike a class, an inner class can be private and once you declare an inner class private, it cannot be accessed from an object outside the class. Following is the program to create an inner class and access it.

In Java programming, nested and inner classes often go hand in hand. A class that is defined within another class is called a nested class. An inner class, on the other hand, is a non-static type, a particular specimen of a nested class.

Java inner class or nested class is a class that is declared inside the class or interface . We use inner classes to logically group classes and interfaces in one place to be more readable and maintainable. Additionally, it can access all the members of the outer class, including private data members and methods.

Inner classes are a security mechanism in Java . We know a class cannot be associated with the access modifier private, but if we have the class as a member of other class, then the inner class can be made private. And this is also used to access the private members of a class.

Use a non-static nested class (or inner class) if you require access to an enclosing instance’s non-public fields and methods . Use a static nested class if you don’t require this access.