A non-static nested class cannot be instantiated without having creating an object of the outer class. code example
Example: inner class vs outer class
1. Can Outer class be static? --> No
2. Can inner class be static? --> Yes
3. Can you create an object from the inner class? --> Only if it's static
4. Can we have main method in inner class ? --> Only if it's static
5. Inner class can only be extended if it's static.