Flatmap vs map in java 8 - Master the Difference! | Java Streams | Part - 1

In this video, we break down the core concepts of map() and flatMap()—without using Java 8 Streams—to help you build a strong foundational understanding before diving into stream-based programming.

Whether you're a beginner or brushing up on Java fundamentals, this deep-dive will clear up the confusion between one-to-one vs one-to-many mappings, and the idea of flattening data structures.

1.Understand the concept of nested lists and why flattening is important.
2.Learn how map() works in a traditional way to transform elements one-to-one.
3.See how flatMap() handles more complex transformations involving nested data.
4.Watch a real-world scenario where flatMap() makes a big difference.
5.Watch a real-world scenario where flatMap() makes a big difference.

⏱️ Timestamps:
00:00:00 - Intro
00:01:53 – What Do You Mean by Flattening a List?
00:23:52 – Map Method for One-to-One Mapping
00:42:15 – FlatMap Method for One-to-Many Mapping
01:06:21 – FlatMap Real-Time Example

🎯 What You’ll Learn:
The difference between map() and flatMap()

Why and when to flatten data

How these concepts translate to real coding situations

#javastreams #streamapi #javatutorial #corejava #coding

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[udaysai]

Hey Abihlash, thanks for sharing map vs flatMap difference !

My understanding of map vs flatMap :
-> map() is used for one-to-one transformation — for each input, there’s one output.
-> flatMap() is used for one-to-many transformation — for each input, it returns multiple values which are flattened into a single List.

[s-vijay-s]

Map is used to convert data from one type to another type whereas Flatmap is used to convert List<List<Object>> to List<Object>

[crimsonx_]

1st comment 😅

Thank you for sharing.

[SivakrishnaPaseda]

Is there any java springboot course from a intermediate to pro sir