Reference no: EM132403132

Exercise

Resolve the following questions:

a) Write a method (you don't need to implement it) that, given an integer array (int []) it is returned in ascending order. You should look into the methods that the Arrays class provides.

b) In Java, the natural order of the objects is defined by the Comparable interface. When an object implements such interface, you can use the compare To method to determine whether an object a is less than, equal, or greater than another object b:

If the result of a.compareTo (b) is negative, then it means a < b

If the result is zero, then it means a = b (equals should return true as well) It the result is positive, then a > b

The Comparable interface is used by the sorting algorithms implemented in Java. Fill in the compare To method in the Song class following the criteria you will find in the comments above the method. After that, you can execute the tests that you can find in the SongCompareTest class. (Hint: in order to sort String objects in lexicographic order you may need to ignore case).

c) Sometimes we may need to sort an object by multiple criteria, apart from the compare To order. In Java you can do this by implementing the Comparator interface. We can create multiple sort criteria for a T class implementing classes that implement Comparator<T>. For instance, we could create a class that instead of sorting integers in their natural order, it sorts them depending on the number of divisors they have.

To compare using this class, we use the compare method, which behaves similarly to compareTo (< 0 if a < b, > 0 if a > b, and 0 if a = b).

The sorting methods implemented in Java also allow using an object from the Comparator class as additional parameter to set a different order as the one provided by Comparable.

In this exercise you will have to implement a sort filter which sorts songs by title and author. You will have to modify the code in the TitleAndAuthorFilter class (edu.uoc.mecm.eda.potify.filters). You can find the matching tests in the Son gComparatorTest class.