Writing generic methods

In this example method :

 

public void printArray(int[] input){
	for(int value : input){
    	System.out.println("%d", value);
    }
}

 

Imagine that we also want similar methods that deal with arrys of String, Doubles or other types.

We could write a new identical methods for each type of array, but that would create a lot of repetitive code.

 

To avoid writing the same method over & over again with different types, we can instead write a generic method like this:

public <E> void printArray(E[] input){
	for ( E element : input){
    	System.out.println("%s", element);
    }
}

 

Notice that we haver replaced references to a specific type int with E;

our generic type. this allows the method to accept any type of array.

 

Also notice the <E> before the method's return type (in this case void); this is the method's type parameter, and is necessary for defining a generic method.

 

We can now use this method to print all of our project's arrays