Classes, fields, methods, constructors, and objects are the building blocks of object-based Java applications. This Java tutorial teaches you how to declare classes, describe attributes via fields ...

You either have to know the type in advance via some other means, or use reflection to get it. <BR><BR>However, to do this you don't need to know the type of objects within the ArrayList at all.

Remember that in Java, for a reference variable of some type referring an object of its supertype is forbidden: arrows in Figure 8 must not be directed upwards.

Object-oriented systems are usually partitioned into layers of related responsibilities and only dependencies in one direction are allowed, from higher layers (more specific, less reusable) to lower ...

Constructors play a key role in all object-oriented programming languages, and Java is no exception. Every class a Java developer creates needs a constructor. Constructors perform numerous important ...