Collections list,set and map

Question

Accepted Answer

List names = new ArrayList<>();

names.add("Alice");

names.add("Bob");

names.add("Charlie");

Set numbers = new HashSet<>();

numbers.add(1);

numbers.add(2);

numbers.add(3);

Map nameToNumber = new HashMap<>();

nameToNumber.put("Alice", 1);

nameToNumber.put("Bob", 2);

nameToNumber.put("Charlie", 3);

Accepted Answer

In Java, the java.util.Collections class is a utility class that contains static methods for operating on collections (which are objects that store other objects). There are three main interfaces in the java.util package that define different types of collections:

List: A List is an ordered collection of elements that allows duplicate values. It provides several methods for inserting, deleting, and accessing elements. Some examples of classes that implement the List interface include ArrayList, LinkedList, and Vector.
Set: A Set is a collection of elements that does not allow duplicate values. It provides methods for adding, removing, and checking for the presence of elements. Some examples of classes that implement the Set interface include HashSet, LinkedHashSet, and TreeSet.
Map: A Map is a collection of key-value pairs. It provides methods for adding, removing, and accessing the values associated with a particular key. Some examples of classes that implement the Map interface include HashMap, LinkedHashMap, and TreeMap.

Accepted Answer

List implementation classes are Array List, LinkedList

implementation classes are HashSet, LinkedHashSet, and TreeSet

Map implementation classes are HashMap, HashTable, TreeMap, ConcurrentHashMap, and LinkedHashMap

Collections list,set and map

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