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Java 9 Programming By Example by Peter Verhas

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Generics

The generics feature was introduced into Java in version 5. To start with an example, our Sortable interface until now was this:

package packt.java9.by.example.ch03; public interface SortableCollection {     Object get(int i);     int size(); }

After introducing generics, it will be as follows:

package packt.java9.by.example.ch03; public interface SortableCollection<E> {     E get(int i);     int size(); }

The E identifier denotes a type. It can be any type. It says that a class is a sortable collection if it implements the interface, namely the two methods— size and get. The get method should return something that is of type E, whatever E is. This may not make too much sense up until now, but you will soon get the point. After all, generics ...

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