List, Set and Map in Salesforce.

Introduction to List:-

List is nothing but it is a class available in salesforce and have the below method.

• List are first and Most Important Data Type.
• Why because every SOQL return the List and we can only do the DML on List Collection Type
• List are Order set of Collection
• Can Contains Duplicate.

Method of List:-

1. Add()
2. Add (Index, element)
3. AddAll()
4. Clear()
5. Clone()
6. Contains()
7. Equals()
8. Get()
9. isEmpty()
10. Remove()
11. Set()
12. Sort()

What is Set?:-

• Set is an unorder collection of Element
• Can not contains duplicate element like list.
• Can not be used to store the SOQL Result

Method of Set:-

• Add()
• Contains()
• Size()
• Clear()
• addAll()

Introduction to MAP:-

Map is a collection of key value pair where key will be unique and value can be duplicate.

• Map => Key, Value
• Unique Key
• Unorder set of collection
• Use Map when you have multiple value related to single key. For example, Account Id as a Key and List of Contacts as a Value.
• To Avoid SOQL inside For Loop

Method of Map:-

• Put()
• containsKey()
• Keyset()
• Values()
• Clear()
• Size()
• get()

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