Difference between List, Set and Map in Java

In JavaCollections Framework, List, Set, and Map are the most commonly used collection types for storing and managing data. Each serves a different purpose based on how elements are stored, accessed, and organized. Understanding their differences helps in selecting the most suitable collection for a particular requirement.

• List stores elements in an ordered sequence and allows duplicate values.
• Set stores only unique elements and does not allow duplicates.
• Map stores data in the form of key-value pairs, where each key must be unique.

Set Interface

The Set interface is a part of the java.util package and is used to store a collection of unique elements. It does not allow duplicate values and is commonly used when data uniqueness is required.

• Stores only unique elements.
• Duplicate values are automatically ignored.
• Provides faster searching compared to a List in many implementations.
• Common implementations are HashSet, LinkedHashSet, and TreeSet.

Syntax:

Set<DataType> setName = new HashSet<>();

Elements in Set: [Apple, Mango, Orange, Banana]
Contains Mango? true
After removing Orange: [Apple, Mango, Banana]
Total Elements: 3

List Interface

The List interface is a part of the java.util package and is used to store an ordered collection of elements. It allows duplicate values and preserves the insertion order of elements.

• Maintains the insertion order of elements.
• Allows duplicate values.
• Supports index-based access to elements.
• Common implementations are ArrayList, LinkedList, and Vector.

Syntax:

List<DataType> listName = new ArrayList<>();

Output :

mango
orange
Grapes

Map Interface

The Map interface is a part of the java.util package and is used to store data in the form of key-value pairs. Each key must be unique, while values can be duplicated.

• Stores data as key-value pairs.
• Keys must be unique.
• Values can be duplicated.
• Common implementations are HashMap, LinkedHashMap, and TreeMap.

Syntax:

Map<KeyType, ValueType> mapName = new HashMap<>();

Output :

100 Amit
101 Vijay
102 Rahul

List vs Set vs Map