What is the difference between a static and a non-static inner class

In Java, inner classes are classes that are defined within another class. There are two main types of inner classes: static inner classes and non-static (also known as inner or member) classes. Here are the key differences between them:

1. Static Inner Class:
   • A static inner class is a nested class that is declared as static.
   • It is associated with its outer class, but it can be instantiated without creating an instance of the outer class.
   • It cannot directly access non-static members of the outer class. It can only access static members of the outer class.
   • It is usually used when the inner class doesn’t require access to instance-specific members of the outer class.

   Example:

   java

   public class OuterClass {
static class StaticInnerClass {
// static inner class members
}
}

2. Non-Static Inner Class:
   • A non-static inner class is a nested class that is not declared as static.
   • It is associated with an instance of the outer class, and it has access to both static and non-static members of the outer class.
   • It cannot exist without an instance of the outer class.
   • It is often used when the inner class needs to access instance-specific members of the outer class.

   Example:

   java

   public class OuterClass {
class InnerClass {
// non-static inner class members
}
}


In summary, the main distinction is that a static inner class is not tied to an instance of the outer class and cannot directly access non-static members of the outer class, whereas a non-static inner class is associated with an instance of the outer class and has access to both static and non-static members of the outer class.