How to implement callback functions in Java?
The callback function is excutable code that is called through a function pointer. You pass a callback function pointer as an argument to other code, or register callback function pointer in somewhere. When something happens, the callback function is invoked. C/C++ allow function pointers as arguments to other functions but there are no pointers in Java. In Java, only objects and primitive data types can be passed to methods of a class. Java’s support of interfaces provides a mechanism by which we can get the equivalent of callbacks. You should declare an interface which declares the function you want to pass. The collections.sort(List list, Comparator c) is an example of implementing callback function in Java. The c is an instance of a class which implements compare(e1, e2) method in the Comparator interface. It sorts the specified list according to the order induced by the specified comparator. All elements in the list must be mutually comparable using the specified comparator. Use i
