Zip It!

🔖 Background Information

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🎯 Problem Statement

Write a Java method called zip(...) that takes two Lists containing elements of the same type and merges them into a single List. The outputed List should alternate between elements of each original List - e.g. an element from the first, then the second, then the first, then the second, etc.

✅ Acceptance Criteria

• Your zip(...) method must merge two Java Lists containing elements of the same type into one List that alternates between elements of each.
• If one List has more elements than the other, the leftover elements should all be placed at the end of the outputed List, in their original order.
• The zip(...) function must use generics so that I can pass in a List containing any type of value - e.g. a list of strings, a list of objects, a list of integers, etc.

📋 Dev Notes

• Although it might seem a bit abstract, you can test generics using JUnit. Be sure to write a set of JUnit tests that ensure that your zip(...) function works as expected with a variety of different value types.

🖥️ Example Output

I might use the zip(...) method in a driver program as shown below:

public static void main(String[] args) {
  List<Integer> nums1 = List.of(1, 3, 5, 7);
  List<Integer> nums2 = List.of(2, 4, 6, 8);
  List<Integer> mergedNumbers = zip(nums1, nums2);
  System.out.println(mergedNumbers); // [1, 2, 3, 4, 5, 6, 7, 8]
 
  List<String> colors1 = List.of("Red", "Green", "Blue");
  List<String> colors2 = List.of("White", "Black", "Orange", "Pink", "Fuschia");
  List<String> mergedWords = zip(colors1, colors2);
  System.out.println(mergedWords); // ["Red", "White", "Green", "Black", "Blue", "Orange", "Pink", "Fuschia"]
}

📝 Thought Provoking Questions

1. How would your code change if you decided to use method overloading rather than generics in this problem?
2. What happens if you try to zip a List<String> and List<Integer> in your code?

💼 Add-Ons For the Portfolio

(Three Credits) Lists to HashMap

Create a new method called hashmapify(...) that takes two arguments. The first argument should be a List<String> and the second should be a List of elements, all having some generic type. The method should create a HashMap where the keys come from the first argument and the values come from the second. If the two list arguments do not have the same size, throw an exception.

public static void main(String[] args) {
  List<String> colors = List.of("White", "Black", "Orange", "Pink");
  List<Integer> nums = List.of(1, 3, 5, 7);
 
  // This should create {"White" => 1, "Black" => 3, "Orange" => 5, "Pink" => 7}
  HashMap<String, Integer> map = hashmapify(colors, nums);
}

🔗 Useful Links

• Java Project Template

📘 Works Cited

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