Which instantiates an instance of inner

An inner class instance can be created only from an outer class instance. An inner class shares a special relationship with an instance of the enclosing class. Instantiating an inner class from within code in outer class:,1 Inner class 2 Method — local inner class 3 Anonymous inner class 4 Static nested class,Inner class acts as a member of the enclosing class and can have any access modifiers: abstract, final, public, protected, private, static.

Inner class can access all members of the outer class including those marked private as shown in the above example where inner class is accessing the private variable "myVar" of outer class. An inner class is declared inside the curly braces of another enclosing class. Inner class is coded inside a Top level class as shown below In object-oriented programming OOP , an inner class or nested class is a class declared entirely within the body of another class or interface.

It is distinguished from a subclass. By contrast, an instance of an inner class cannot be instantiated without being bound to a top-level class. An instance of a normal or top-level class can exist on its own. Let us take the abstract notion of a Car with four Wheel s. Our Wheel s have a specific feature that relies on being part of our Car. This notion does not represent the Wheel s as Wheel s in a more general form that could be part of any vehicle.

Instead, it represents them as specific to a Car. We can model this notion using inner classes as follows:. This process is automatic. Also, if the nested type is a static enum , of course you can't instantiate it at all.

An inner class is a nested class that is not explicitly or implicitly declared static. That is, according to JLS terminology, an inner class is one that isn't static. If it's static , then it's just a nested type. It is legal. The fact that the inner class is static gives you a benefit here; its instances are not bound to any instance of the containing class, so they can be freely instantiated as long as the access qualifier allows it.

Python Javascript Linux Cheat sheet Contact. A nested class is simply a class definition that is marked "static" inside of another, "outer" class definition. Being marked static means that the nested class definition exists at the class level of the outer class.

Since they are declared static, nested classes cannot be defined inside of a method. Inner classes declartions are not marked static and thus exist at the instance level of a the outer class. Since inner classes are not static, they can be defined inside of a method. Because of this, inner classes are scoped to anything that would normally be in scope at that level of curly-brace indention.

Scoping restriction : In order for an inner class to access a local variable, that variable MUST be declared final or be "effectively final ", meaning that the variable itself cannot ever be reassigned, i. If the inner class references a non-final local variable that is mutated anywhere in the code, a compiler error will be thrown.