Java Collections Framework: Basics to Advanced Techniques

Define an ArrayList of strings to store song data, explore generics, load and print the song list from a file, and parse lines to extract artist name.

Fetch data from a file by chaining a buffered reader, handle file not found with try-catch, read lines, extract song titles by splitting on '/', and store them in ArrayList.

Learn to sort an ArrayList with collections.sort, understand how tree set keeps data sorted and unique, and recognize when to rely on natural ordering and the comparable interface.

Extend the jukebox to store song objects in an ArrayList and create a song class with title, artist, rating, and bpm. Override toString for readable output when listing songs.

Explore how overriding toString enables meaningful printouts of song objects, use generics with ArrayList<Song>, and understand sorting challenges and type safety when using a four-token song parser.

Learn how to sort song objects with Collections.sort, using generics for type safety and reading the Java API docs to apply the correct comparison target.

Explore creating instances of generic classes like ArrayList, declaring and assigning animal lists, and writing methods that accept generic types, while examining polymorphism in the collection framework.

Explore how generic classes work by examining ArrayList, using E as the element placeholder, and instantiating with new ArrayList<String> to show how E substitutes the chosen type.

Learn how generics use type parameters like E and T in ArrayList to enforce type safety and compile-time checks, explore documentation conventions, and implement generic classes and methods.

Explore how to write generic methods in Java, including using class type parameters and methods with their own type parameters, and compare signatures like T extends animal versus ArrayList animal.

Create a Java animal class with name and color, extend it with dog having breed, and explore generic methods using List<T> and ArrayList to illustrate polymorphism.

Explore why the sort method requires a type that extends Comparable. Learn how to implement Comparable in a Song class to enable sorting by title in an ArrayList.

Implement the comparable interface in the song class to enable sorting by title using string compareTo, and sort songs with collections.sort, with a preview of comparator.

Implement the Comparable interface in the song class to enable sorting via compareTo. Then use an external Comparator and the overloaded sort method to order by title or artist.

Learn to use a comparator to sort a song list without implementing comparable, by creating an inner class that implements comparator and invoking the overloaded sort method.

Learn to use hashset to avoid duplicates when loading songs from a file, compare list, set, and map roles, and leverage addAll to populate the hashset from a song collection.

Explore reference equality, object equality, default hashCode behavior based on memory address, and how overriding hashCode and equals guides HashSet in handling duplicates.

Override hashCode and equals to define object equality by title, using the string hashCode, and follow the rule that equal objects share a hashCode, enabling hashset bucketing.

Master TreeSet, the sorted set in Java collections framework, which prevents duplicates and maintains order with a comparator or compareTo. Learn constructor options and performance trade-offs using a jukebox example.

Understand how TreeSet handles custom objects, requiring a comparable implementation or a comparator via the constructor, and how a non comparable book can trigger a runtime exception.

Develop skills in writing generic methods and applying type parameters, including using class-defined type parameters and methods with explicit type parameters like T extends animal, alongside ArrayList usage.

Explore generic methods in Java, comparing a generic method with a non-generic version using animal, dog, and cat classes, and learn how type bounds affect which ArrayLists are accepted.

Explore how to write generic classes and methods, why a Song list must implement Comparable to be sorted, and how to sort songs by title using the compareTo contract.

Explore how maps store key-value pairs with unique keys, using a telephone directory analogy, and compare hash map, tree map, and hash table for concurrency and thread safety.

Explore how hash map stores key–value pairs, including null keys and values, non-ordered retrieval, and overwriting with put, while comparing hash map with hash table and highlighting performance and thread-safety.

Display the elements of a map using entrySet to obtain a set view of key-value mappings, then iterate with an iterator and print each key and value via Map.Entry.

Explore how to access keys and values in a hash map using entry set and key set, iterate entries with iterators, and retrieve values via get and key-based lookups.

Learn how to retrieve a value by key in a hash map, remove by key or key-value, and perform size, isEmpty, contains, replace, iterate via entrySet, and preview tree map.

Java's tree map implementation stores key-value pairs in ascending order, enforces unique keys and no null keys constraint, and demonstrates practical instantiation with generics.

See how a tree map stores integer keys and string values, uses put to insert and replace, iterates with keySet in ascending order, and removes by key or key-value pair.

Explore sorting a tree map with custom object keys by defining an employee class with name and salary, including constructors, getters, setters, and a toString override.

Explore how to use TreeMap with a custom comparator to sort by name, implement comparator versus comparable, and print results via the key set and iteration.

Print employee objects with their toString methods and demonstrate sorting by salary using a custom comparator in a tree map, then print the ordered results.

Explore wild cards in the Java collections framework, examining generics, polymorphism rules, and the difference between arrays and generic lists, with practical examples using animals, dogs, and cats.

Declare and create a dog array, show type safety with animal arrays, and use a polymorphic Animal[] parameter to handle dogs and cats, then switch to ArrayList<Animal> with generics.

Explore why an ArrayList of dogs cannot be passed to a method accepting an ArrayList of animals, compare array and collection checks, and preview the wild cards concept.

Learn how wild cards and generics manage polymorphism in collections, restricting modifications to lists and enabling safe method arguments, with practical syntax options and comparisons of comparable and comparator approaches.