Use JAVA language.

// A StringSet is a collection of non-null strings, with no duplicates // (i.e., no two elements may be equal). public class StringSet {

public StringSet() { }

// Computes and returns the union of the StringSet that calls this method and the

// StringSet argument to the method.

// The original StringSets should not be changed. The union set contains every

// element of each of the original StringSets.

// Throws an IllegalArgumentException if other is null.

public StringSet union(StringSet other) {

return new StringSet();

}

// Computes and returns the intersection of the StringSet that calls this method

// and the StringSet argument to the method.

// The original StringSets should not be changed. The intersection set contains

// only the elements that are in both of the StringSets.

// Throws an IllegalArgumentException if other is null.

public StringSet intersection(StringSet other) {

return new StringSet();

}

}