Calling On Object In Order To Take Union

How do I take the union between an object called on and the object passed in the parameter?I have an interface:

Java Code:

import java.util.Set;
/**
* An extended Set where additional functionality is added
*/
public interface NewSet<T> extends Set<T> {

[code]...

Now, the union method requires a NewSet object to be called on. The Union will be performed between the object called on and the object passed in the parameter, which is set.How do I call on a NewSet object in order to take the union between the object called on and the object passed in?Do I just do:

Java Code:

public NewSet<T> union(NewSet<T> set) {
NewSet<T> calledOn = new ArrayList<T>();
// ...
} mh_sh_highlight_all('java');