HashSet in Java is part of the Java Collections framework and one of the most used Set implementation in Java applications. HashSet class extends AbstractSet class and implements Set, Cloneable and Serializable interfaces. HashSet is backed by a HashMap instance that means HashSet class internally uses HashMap to store its…
This post shows how to sort a HashSet in Java. Since HashSet is an unordered collection so you will need to convert it to another collection in order to sort a HashSet. There are two options to sort a HashSet by converting it to another collection. Convert HashSet to list…
CopyOnWriteArraySet in Java extends the AbstractSet which in turn implements the Set interface and is part of java.util.concurrent package. How CopyOnWriteArraySet differs from other Set implementations in Java Collections framework is that it is thread-safe. Table of contents CopyOnWriteArraySet internal implementation in Java Features of the CopyOnWriteArraySet Java CopyOnWriteArraySet constructors…
ConcurrentSkipListSet in Java is a sorted set just like TreeSet but it is also scalable and concurrent so ConcurrentSkipListSet is thread-safe and can be accessed by multiple threads safely. In ConcurrentSkipListSet operations like add and remove are done atomically using compare and swap (CAS). These are lock-free so overhead of…
If you have to store only unique elements i.e no duplicates in your Java application you’d probably choose to use one of the Set implementation in Java; HashSet, TreeSet or LinkedHashSet. Though all these Set implementations store unique elements but they do differ on the points like ordering of elements,…
TreeSet in Java is one of the implementation of the Set interface. How it differs from the other popular implementation HashSet is that unlike HashSet which is unordered, TreeSet stores its element in sorted order. The elements in TreeSet are ordered using their natural ordering, or by a Comparator provided…
LinkedHashSet in Java is also one of the implementation of the Set interface like HashSet and Treeset. How LinkedHashSet differs from the other implementation HashSet is that unlike HashSet which is unordered, LinkedHashSet is an ordered collection, it maintains iteration ordering, which is the order in which elements were inserted…
This post shows how to synchronize HashSet in Java and the HashSet’s thread safe alternative which can be used instead of a HashSet. HashSet is not thread safe HashSet in Java is not thread safe as it is not synchronized by default. If you are using HashSet in a multi-threaded…
HashSet internal implementation in Java or how does HashSet work internally in Java is a very important interview question. Some of the important points that you should know are- What is the backing data structure for HashSet or where does HashSet stores its element? How does add() method work in…
In this post we’ll see different ways to iterate a Set or HashSet in Java. Your options to iterate a HashSet are as follows- You can use For-Each loop (Advanced or enhanced for loop), available from Java 5. You can iterate a HashSet using Iterator. Using iterator() method you can…
