What is interface in Java? What are the differences between interface and class?

What is an interface?

In Java, an interface is similar to a class. It is a reference type with a collection of abstract methods.

An interface contains the following items:

Interface usually does not contain method body. The Method bodies exist in case of default methods and static methods.

An interface can have any number of methods similar to a class.
Like java class an interface is written in a file with a .java extension
Similar to the java class, the name of the interface has to match with the name of the file.
The byte code of an interface written in a .class file which is the case of java class.

An interface does not contain any constructors.
We cannot instantiate an interface.
All of the methods in an interface are abstract.
An interface is implemented by a class not extended by a class
Fields in an interface must be declared both static and final as it cannot contain instance fields.

Class	Interface
A class describes the attributes and behaviors of an object.	An interface contains behaviors that a class implements.
A class can have abstract methods, concrete methods.	An interface can have only abstract methods.
Members of a class can be public, private, protected or default.	All the members of an interface are public by default.