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ArrayList Exercises

This directory contains exercises to help you practice working with ArrayList collections in Java using jshell.

Setup

  1. Open your terminal/command prompt
  2. Navigate to this directory
  3. Start jshell: jshell
  4. Load the exercise file: /open topic.jsh

Exercises

Exercise 1: ArrayList Basics

Write a method createStringList() that creates and returns a new ArrayList of Strings. Write a method getListSize(ArrayList<String> list) that returns the size of an ArrayList (handle null).

Exercise 2: Adding Elements

Write a method addToEnd(ArrayList<String> list, String item) that adds an item to the end of the list. Write a method addToBeginning(ArrayList<String> list, String item) that adds an item to the beginning of the list. Write a method addAtPosition(ArrayList<String> list, int index, String item) that adds an item at a specific position.

Exercise 3: Accessing Elements

Write a method getFirstItem(ArrayList<String> list) that returns the first item (return null if empty). Write a method getLastItem(ArrayList<String> list) that returns the last item (return null if empty). Write a method getItemAt(ArrayList<String> list, int index) that returns the item at a specific index (handle out of bounds).

Exercise 4: Searching and Contains

Write a method containsItem(ArrayList<String> list, String item) that returns true if the list contains the item. Write a method findPosition(ArrayList<String> list, String item) that returns the index of the first occurrence (-1 if not found). Write a method countOccurrences(ArrayList<String> list, String item) that counts how many times an item appears.

Exercise 5: Removing Elements

Write a method removeFirstItem(ArrayList<String> list) that removes and returns the first item. Write a method removeLastItem(ArrayList<String> list) that removes and returns the last item. Write a method removeAtPosition(ArrayList<String> list, int index) that removes the item at a specific index. Write a method removeAllOccurrences(ArrayList<String> list, String item) that removes all occurrences of an item.

Exercise 6: List Operations

Write a method clearList(ArrayList<String> list) that removes all items from the list. Write a method copyList(ArrayList<String> original) that creates a copy of the list. Write a method mergeLists(ArrayList<String> list1, ArrayList<String> list2) that combines two lists into one.

Exercise 7: List Analysis

Write a method findLongestString(ArrayList<String> list) that returns the longest string in the list. Write a method sortList(ArrayList<String> list) that sorts the list alphabetically. Write a method convertToArray(ArrayList<String> list) that converts the ArrayList to a String array.

Testing Your Code

After completing each exercise, test your methods with different inputs:

// Example tests
ArrayList<String> list = createStringList();
addToEnd(list, "Apple");
addToEnd(list, "Banana");
getListSize(list)                          // Should return 2
getFirstItem(list)                         // Should return "Apple"
containsItem(list, "Apple")                // Should return true
findPosition(list, "Banana")               // Should return 1
removeFirstItem(list)                      // Should return "Apple"

Tips

  • Read the NOTES.md file first to understand ArrayList collections
  • Remember that ArrayList indices start at 0
  • Always check for null and empty lists to avoid exceptions
  • Use generics (ArrayList) for type safety
  • ArrayList automatically resizes as you add/remove elements
  • Be careful with index bounds when accessing elements