Member Inner Classes In Java

Member Inner Classes ( Non-static Inner Classes )

A non-static inner class, often just called an inner class, is a class that is defined inside another class and is associated with an instance of the outer class.

Key Points:

Inner classes can access both static and non-static members of the outer class.
They have a reference to the outer class's instance, allowing them to interact with the outer class's instance variables and methods.
Inner classes are typically used when you want to encapsulate helper classes or functionality that is closely related to the outer class.

Use Cases:

Non-static inner classes are useful when the inner class requires access to the outer class's instance variables or methods.
They are commonly used in implementing data structures like linked lists, trees, and in GUI applications where event listeners are implemented as inner classes.

Code Example

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public class OuterClass {    private String outerInstanceVar = "Outer Instance Variable";​    // Non-static inner class    public class InnerClass {        public void display() {            // Can access instance variables of the outer class            System.out.println("Inner Class: " + outerInstanceVar);        }    }​    public static void main(String[] args) {        // Create an instance of the outer class        OuterClass outerObject = new OuterClass();​        // Create an instance of the inner class        OuterClass.InnerClass innerObject = outerObject.new InnerClass();        innerObject.display();    }}

Output

Inner Class: Outer Instance Variable

Member Inner Classes ( Non-static Inner Classes )

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