Java Map

The Java Map interface represents a collection that contains key + value pairs. This Java Map tutorial explains the the basics of using a Map in Java, as well as the most common Java Map methods.

Chapters
0:00 Java Map Introduction
1:46 Java Map Interface Implementations
2:55 Java Map Generic Types
5:10 Java Map Insert Key + Value Pair
6:30 Java Map Null Key and Null Value
7:20 Java Map Insert all Key + Value Pairs From One Map Into Another Map
8:16 Java Map Size
8:51 Java Map Check if Map is Empty
9:39 Java Map Check if Map Contains Key
10:24 Java Map Check if Map Contains Value
11:05 Java Map Remove Key + Value Pair
12:10 Java Map Remove All Entries
12:32 Java Map Replace Value for Key
13:19 Java Map Iterate Keys Using Iterator
14:46 Java Map Iterate Keys Using for-each Loop
15:43 Java Map Iterate Entries Using Java Streams API
16:55 Java Map Difference Between HashMap and TreeMap
19:00 Java Map More Resources

Textual version of this Java Map tutorial:

Java List tutorial video:

Java Set tutorial video:

Java Collections tutorial - textual version

Java Streams API video:

Java Lambda Expressions videos:

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[hydeesabile]

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[utkuceylan]

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[TheHoppchen]

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[gopikrishna]

I really like the way you explained. I'm glad that my first video to learn about Map interface thorough this video.

[AhamedKabeer-wnjb]

Wow amazing explanation..good examples..Thank you Sir..

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[SwordSK]

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[danmurraypiano]

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[CoVerseAU]

Thanks, Jakob, very useful Map refresher. I enjoy your tutorials, especially the concurrency one. Great job!

[joneswafula]

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[nooralmanasrah]

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[Kisyov]

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[MsGeorge]

thank you so much for your videos, great explaining

[HenryLeu]

On line #2 and #3, how does the interface Map.Entry know what implementation to use for getKey() and getValue()?
getKey() and getValue() are abstract methods inside the interface Map.Entry.

Map.Entry<Integer, String> en = Map.entry(12, "YYY");
System.out.println( en.getKey() );
System.out.println( en.getValue() );