No. Interfaces themselves cannot be instantiated, so in order to be useful you must make a subclass. The final keyword will make a class unable to be extended, which would defeat the point of using an interface.
yes we can define a variable in an interface in java.
NO, we cannot create a contructor for an interface in java.
interface is a list of methods which implements that interface
A tagging interface type in Java is an interface that has not defined methods such as the java.io.Serializable interface.
The final keyword in JAVA means that the class can no longer be derived, i.e. it cannot be used as a base class for a new child class.If you declare a method as final, this method cannot be overridden in any of the child class that may extend this class.
Runnable interface
Yes. This is a valid interface definition in Java: interface Useless {}
An interface in Java is like an abstract class, but there are no method bodies allowed in it and it has to be declared with the interface keyword. It is Java's way of getting around the Deadly Diamond of Death. Only abstract methods and constants are allowed in it.
Interface is collection of abstract methods which has only declaration and no implementation
Interface Java can be used for a variety of tasks and commands such as .swf files, Java files, running scripts, as well as website video players for websites.
maybe
According to a beginner's book on Java, an interface can't have constructors. Also, the interface itself can't contain the method implementation.