interfacekeyword. Interfaces can contain only constants, method signatures, default methods, static methods, and nested types. Method bodies exist only for default methods and static methods. Like abstract classes, Interfaces cannot be instantiated—they can only be implemented by classes or extended by other interfaces. Interface is a common way to achieve full abstraction in Java.
An Intent is a small message passed around the Android system. This message may hold information about our intention to perform a task.
It is basically a passive data structure holding an abstract description of an action to be performed.
Function pointers are pointers that point to functions instead of data types. They can be used to allow variability in the function that is to be called, at run-time.
A pointer is a type of variable which can store the address of another object or a function.