Constructors are methods in a class that are invoked when an instance of that class is created. Their main responsibility is to leave the new object in a useful and consistent state.
Destructors/Finalizers are methods in a class that are invoked when an instance of that is destroyed. In C# they are rarely explicitely written/used.
The collections framework in
java.util provides a number of generic classes for sets of data with functionality that can't be provided by regular arrays.
Collections framework contains interfaces for
Collection<O>, with main sub-interfaces
Set<O>, and mapping collection
Map<K,V>. Collections are the root interface and are being implemented by many other collection frameworks.
Concurrent computing is a form of computing in which several computations are executed concurrently instead of sequentially. Java language is designed to support concurrent programming through the usage of threads. Objects and resources can be accessed by multiple threads; each thread can potentially access any object in the program and the programmer must ensure read and write access to objects is properly synchronized between threads.
List comprehensions in Python are concise, syntactic constructs. They can be utilized to generate lists from other lists by applying functions to each element in the list. The following section explains and demonstrates the use of these expressions.