A generics working example: how to embed two classes

From WikiJava

I'd like to introduce you a very important forward leap towards a stronger typization in the Java 5 language: generics.

This is a full working example.

the article

The following class Pair has 2 type parameters, E and F, and its instances are pair of objects where we have defined the obvious projections. Look out the type variables in the body of the class.

This class could be useful in the quite common situation where a method has to return 2 values.

Be careful that the filename .java and the constructor of the generic class are just Pair and NOT Pair<E,F>.

Note also that when you declare more than one formal parameter these are bounded between a single couple of angular parenthesis and separated by commas.

Pair.java

public class Pair<E,F> {
    // internal rappresentation
    private E first;
    private F second;
 
    // constructor
    public Pair(E first, F second){
	this.first = first;
	this.second = second;
    }
 
    public E getFirst() {
      return first;
    }
 
    public F getSecond() {
      return second;
    }
 
    // toString - overridden from Object
    public String toString(){
	return "("+ first + "," + second + ")";
    }
}

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