Java Collections from basics to Advanced

Learn how multidimensional arrays are arrays of arrays, from two dimensional to three dimensional structures and their base size syntax.

We test various Java array declaration syntaxes to predict compilation, identify the most precise forms, and understand where dimensions belong, across 1D, 2D, and 3D patterns.

Learn how to traverse arrays using for each and for loops, access elements by index, and print 1D, 2D, and 3D array elements with a length variable.

Learn how to assign and reassign array objects to references, see shared arrays update across references, and explore string and object array compatibility and short[] to int[] limits.

Learn how to use anonymous arrays in Java by creating unnamed arrays inside methods or as arguments, then sum their elements with a for-each loop.

Master arrays in Java from single to multi-dimensional forms, covering declaration and initialization, various syntaxes, creating array objects, traversal of both single and multi-dimensional arrays, element assignments, and anonymous arrays.

Discover how collections overcome arrays by offering growable size and flexible data types. Understand how predefined methods and underlying data structures enable efficient operations and reduce coding effort.

Explore the Java collections framework, its interfaces, implementations, and algorithms for organizing data. Compare list, set, map, and queue models and see key examples like HashMap, TreeMap, LinkedHashSet, and PriorityQueue.

The collection interface, as the first interface in the collection framework, defines common methods such as add, add all, remove, clear, contains, is empty, size, iterator, and to array.

Distinguish the collection interface from the collections utility class in java.util; collection is the base interface for list, set, and queue, while collections provides static methods like sort and shuffle.

Analyze how generics enforce type safety in collections, replace fragile typecasting with compile-time checks, and compare arrays to ArrayList in a statically typed Java environment.

Explore the Java stack class, a vector-based last in, first out data structure that supports push, pop, peak, and search, preserves insertion order, and accepts duplicates and heterogeneous objects.

Recap the List interface and its implementations—ArrayList, LinkedList, Vector, and Stack—covering insertion order, duplicates, and iterators, with next lecture on the set interface.

Explore linked hash set, a hash set subclass that preserves insertion order with a hybrid linked list and hash table structure, supports standard set operations and constructors.

Explore navigable set as a child of sorted set, implemented by a tree set, and use navigation methods—floor, lower, ceiling, higher, first, last—and the descending set to view order.

Explore how TreeSet implements navigable and sorted sets, enforces uniqueness, and sorts elements with a balanced tree using either natural ordering (elements implement Comparable) or a comparator.

Explore set concepts and implementation classes like HashSet, LinkedHashSet, and TreeSet, and learn how SortedSet and NavigableSet handle duplicates, insertion order, and the roles of Comparable and Comparator.

Explore the priority queue, a queue subclass that orders inserts by natural or custom sorting, disallows nulls and duplicates, with constructors for default size and capacity, plus collection-based creation.

Understand hashing, including how a hash function yields an address, how hashCode and equals relate, and how to store items in a hash table with modulo and collision linked lists.

Explore the internal working of hashmaps in Java, including constructors, initial capacity, and load factor, and learn how keys, values, and buckets are managed with put and get.

Compare hash map and hash table, highlighting non synchronized versus synchronized access. Note how HashMap allows null keys and values, while HashTable forbids nulls and is legacy.

Learn how identity hash map differs from hash map by using reference equality to compare keys, allowing distinct object references with identical values, unlike hash map which uses equals.

Compare hash map and weak hash map: weak map keys are garbage collected when unreferenced, unlike strong references in hash map. Weak hash map lacks serializable and clonable features.

Explore the sorted map interface that stores key-value pairs in ascending key order, with keys sorted by natural order or a comparator, disallowing nulls, via TreeMap and navigable map.