Java Collections and Streams

Collections Framework Overview and the List Interface The Java Collections Framework (JCF) is a unified set of interfaces and implementations for storing, organizing, and ...

ArrayList vs LinkedList: How to Choose Two of the most common List implementations are ArrayList and LinkedList . They look identical from the outside because both implement ...

Set Implementations: HashSet, LinkedHashSet, and TreeSet A Set is a collection with no duplicate elements. It models the mathematical idea of a set, and Java offers three main ...

Map Implementations: HashMap, TreeMap, and Friends A Map stores keys mapped to values and is arguably the most used data structure in Java after the List . Each key can appear ...

Sorting with Comparable and Comparator Sorting is everywhere in application code, and Java makes it both simple and dangerous: if you sort without thinking about contracts, you ...

equals and hashCode: The Contract Explained Every Java object inherits equals and hashCode from Object . Overriding them correctly is the difference between working hash ...

Generics and Collections: Type Safety in Practice Generics let you write collection code that is checked at compile time. Instead of storing Object and casting everywhere, you ...

Java Streams: The Pipeline Model Introduced in Java 8, the Streams API offers a functional way to process sequences of data. A stream is not a data structure; it is a lazily ...

map, filter, and reduce: The Core Stream Operations Three operations form the backbone of most stream pipelines: map transforms values, filter selects values, and reduce ...

Collectors, groupingBy, and Parallel Streams Collectors turn streams back into useful structures, and groupingBy builds maps of grouped data in one line. Parallel streams can ...