What is the need of Collection framework in Java since all the data operations(sorting/adding/deleting) are possible with Arrays and moreover array is suitable for memory consumption and performanc... More on stackoverflow.com

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what are data structures that are most commonly used and that everyone should know? You need to know the collection interfaces and when to use them: List, Set, Queue, Map. but are there any others? Yes, there are many many implementations of the afore mentioned interfaces, of which the following are more commonly known: lists: ArrayList, LinkedList sets: HashSet, TreeSet, LinkedHashSet, queues: ArrayBlockingQueue, maps: HashMap, TreeMap, LinkedHashMap, ConcurrentHashMap What are some important thing that someone learning Collections framework should know? Learn when to use lists, sets, queues and maps Learn the differences between implementations, like how is a TreeSet different from a HashSet, what problems they are designed to solve and when you should use each of them Learn about immutability, i.e. how to create a collection that cannot be modified afterwards and when you should use it Learn about thread-safety of collections, i.e. can a collection be used safely in a multithreaded environment, and if not, how can you make it safe Learn about collection streams, which will also be a good intro into functional-style programming More on reddit.com

Yes, the Java collections framework is important. It's used by nearly every Java project small or large, real-time or no. The Java collections framework is just things like Sets, Maps, and Queues. Super useful, general-purpose stuff that nearly all programs need - plus some special concurrent versions where needed, algorithms to operate on them, and more. You don't need to be an expert in the whole thing. But you should be familiar with a few of the more common classes and how to use them. More on reddit.com