In java we have 6 basic programming elements to develop below are 6 types of applications. Below diagram shows the 6 basic programming elements hierarchy
Package- it is a java folder used to group related classes, interfaces and enums also used to seperate new classes from existed classes if both have same name.
3. interface - All these three are java files used to group Java data and logic. enum was introduced in Java 5.
5. Variable - it is a named memory location used to store Java data, such as numbers, characters, string etc.
6. Method - It is sub block of a class used to implement logic of an object operations.
What is the difference between class, interface and enum ?
Interface is fully unimplemented class, it is used for defining set object operations, where as the class is a fully implemented class, it is used for implementing an object operations.
So interface does not allow methods with logic but class allows methods with logic.
For example: Bank is the object created as interface in java and HDFCBank , ICICIBank are created as classes with bank operations withdraw, deposit implementations.