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Difference between List and Set in Java Collection? Example

Sets implement every method in the Collection interface, but they do so in a way that makes sure no element appears more than once in the set. TreeSet and HashSet are the two Java classes that implement the interface Set. List allows duplicates while Set doesn’t allow duplicate elements . It actually returns a delta providing the list of elements added and remove.

Map and SortedMap are the two interfaces, and TreeMap, LinkedHashMap, and HashMap are three classes of Map. In the above example, we have used the Guava library to get the difference between two sets. In order to run this program, you need to implement Guava Library by adding it in your dependency.

Since lists are ordered, position indexing is allowed in them. However, in unordered items like sets, positional indexing is not possible. List, Set, and Map interfaces are very important part of collection framework. List and Set implements Collection interface but Map does not. You should then use the addAll() method to add the array elements, i.e., a collection, to the set. As you can see, it has created two integer arrays and two sets in the example above.

For example, contains returns false when passed an object that equals a set member, but isn’t the same instance. This behavior is similar to the way IdentityHashMap handles key lookups. Method returns listIterator to iterate over elements in List in java. You will then use the removeAll() method to remove all the array elements present in the set. You must create a set object, add a few elements to it, and then cleared it with the clear() method in the following example.

This method is just a small convenience for creating an empty set and then calling Iterables.addAll(java.util.Collection, java.lang.Iterable). This method is not very useful and will likely be deprecated in the future. Returns a new, mutable EnumSet instance containing the given elements in their natural order. This method behaves identically to EnumSet.copyOf, but also accepts non-Collection iterables and empty iterables. ()Returns a Collector that accumulates the input elements into a new ImmutableSetwith an implementation specialized for enums. An unmodifiable view of a set which may be backed by other sets; this view will change as the backing sets do.

In JDK 2.0, we used to use Vectors, Arrays, and Hashtable to group the objects into a single unit. In JDK 8, Collection framework come in to existence that provides several interfaces to work with a collection of data. List and Set interfaces are one of them that are used to group the object. The main difference between List and Set is that Set is unordered and contains different elements, whereas the list is ordered and can contain the same elements in it. Two objects per Entry e.g. a key and a value and It may contain duplicate values but keys are always unique. See here for more differences between List and Set data structure in Java.

Creates a mutable HashSet instance initially containing the given elements. Use Collections.newSetFromMap(java.util.Map) instead. (E… elements)Creates a mutable HashSet instance initially containing the given elements. To learn more about collections in Java, check this out. Thought LinkedHashMap maintains insertion order of keys in java. Unknownsaid…I was asked this question in my last interview.

List is a kind of array whose size grow as we add elements to the list. Both of them maintains the collection of elements or objects. Returns an unmodifiable view of the specified navigable set.

Returns a unmodifiable view containing the difference of the given Sets, denoted by a \ b (or a – b). An unmodifiable view of a set that may be backed by smsu mba other sets. This method delegates to the appropriate methods of NavigableSet (namely subSet(), tailSet(), and headSet()) to actually construct the view.

The Collection interface is expanded by the Set interface. A set interface is a group or collection of objects without any duplicates. This implies that there cannot be two references to the same object, one reference to two objects, or two references to Null. The elements’ sequence or order is unimportant, but that does not mean that the ordered set is forbidden. Each one implements the interface Collection and, by extension, the interface List. Although the objects are stored in nodes that are connected by pointers, an object of type LinkedList still represents an ordered sequence of objects of type T.