Read CSV into HashMap in Java 📂

Learn how to load CSV data into a HashMap in Java and print its keys and values with this comprehensive guide.
---
This video is based on the question https://stackoverflow.com/q/66959019/ asked by the user 'Drew Davis' ( https://stackoverflow.com/u/15560201/ ) and on the answer https://stackoverflow.com/a/66959363/ provided by the user 'Nikolay Bondarchuk' ( https://stackoverflow.com/u/12962623/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Java: pass from CSV into HashMap and Print Key and values

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/licensing
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/by-sa/4.0/ ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/by-sa/4.0/ ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
How to Read a CSV File into a HashMap in Java

When dealing with CSV (Comma Separated Values) files in Java, one common task is to load data into a structure that allows for easier access—such as a HashMap. However, if you're encountering issues with your implementation, such as seeing only empty brackets when printing your HashMap, you're not alone. Let's explore how to correctly read data from a CSV file, store it in a HashMap, and print the keys and values.

The Problem

You have a CSV file that contains multiple rows of data, like so:

[[See Video to Reveal this Text or Code Snippet]]

The goal is to read this data into a HashMap where the key is a person's name and the value is an object containing their age and height. If your output is consistently showing {} (indicating an empty HashMap), it means that you haven't successfully populated the map with any data.

Understanding the Solution

Here's a step-by-step guide to correctly load data from your CSV into a HashMap.

1. Define a Class for Your Data

First, you need to create a class that will represent a person, encapsulating relevant details like name, age, and height. Here's a simple implementation:

[[See Video to Reveal this Text or Code Snippet]]

2. Read the CSV File

Next, use a Scanner to read the CSV file line by line. Make sure to split each line into its components:

[[See Video to Reveal this Text or Code Snippet]]

3. Print the HashMap

Finally, after populating the HashMap, print it out to see the keys and their associated values:

[[See Video to Reveal this Text or Code Snippet]]

Complete Example Code

Here is the complete code that puts the aforementioned steps together:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

Implementing this approach should resolve your issue of the empty HashMap. Make sure to adjust your file path to where your CSV file is located, and you should be able to see the data correctly populated in the console output. Happy coding!