Java - Generics

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http://docs.oracle.com/javase/tutorial/java/generics/index.html
http://www.javacodegeeks.com/2011/04/java-generics-quick-tutorial.html
http://tutorials.jenkov.com/java-generics/index.html

// Generics improves type safety.  It introduces the construct <>:

ArrayList<Animal> = new ArrayList<Animal>();

List<? extends Animal> list = animalsList;
List<? super Animal> superList = dummy;

// The extends keyword in the above example indicates that it would accept 
// objects of classes that inherit from the Animal class.

// The super keyword in the above example indicates that it would accepts 
// objects of classes that the Animal class inherit from.

// Generics also help with avoiding having to cast.

// The generics facility introduced the concept of type variable. A type variable 
// is an unqualified identifier introduced by:
// 1. Generic class declarations
// 2. Generic interface declarations
// 3. Generic method declarations
// 4. Generic constructor declarations.

public interface List<T> extends Collection<T> {
...
}
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