Practice with Interfaces

Practice: String Length Comparable Parameterized

Created By: Geoffrey Challen

/ Version: 2021.10.0

Create a public class named MyString. MyString should provide a public constructor that accepts a single String argument. Your string variable should be private.

MyString should also implement the Comparable interface. Normally Strings are compared lexicographically: "aa" comes before "z". MyString should compare instances based on the length of its stored String. So MyString("aaa") should come after MyString("z"), since "aaa" is longer than "z".

Note that you should implement Comparable<MyString>, meaning that MyString instances can be compared with other MyString instances but not with other objects. As a result, the signature of compareTo will be fun compareTo(other: MyString): Int, accepting a MyString rather than Any.

You will probably need to review the documentation for Comparable.

Practice: Both Greater Comparable

Created By: Geoffrey Challen

/ Version: 2021.10.0

Create a class named BothGreater that stores two Int values set by the primary constructor. Neither should be publicly visible. BothGreater should also implement the Comparable<BothGreater> interface, returning 1 for a positive result and -1 for a negative result. An instance of BothGreater is greater than a second instance if both Int values are larger, and is lesser than if both Int values are smaller. Otherwise, compareTo should return 0.

You will probably need to review the documentation for Comparable. (Note that this is Java documentation.) Because we are using the type parameter BothGreater to the Comparable interface, compareTo accepts an BothGreater as an argument.

Homework: Closer To A Pole

Created By: Geoffrey Challen

/ Version: 2022.10.0

Create a class named Position that stores two Double fields set by the primary constructor: a latitude and longitude value, passed in that order. Neither should be publicly visible. Your constructor should reject invalid latitude and longitude values. Valid longitude values are between -180.0 and 180.0, inclusive, while valid latitude values are between -90.0 and 90.0, inclusive.

Position should also implement the Comparable<Position> interface, returning 1 for a positive result and -1 for a negative result. An instance of Position is greater than a second instance if it is closer to either the North or South Pole, is lesser than the second instance if it is farther from the North or South Pole, and equal if it is at the same distance. The instance passed to compareTo will not be null.

You will probably need to review the documentation for Comparable. (Note that this is Java documentation.) Because we are using the type parameter Position to the Comparable interface, compareTo accepts an Position as an argument.