You don’t know Java Streams in-practice , Do You?

If you’re not familiar with Java Streams, it is a powerful tool introduced Java 8 onwards, that can help you write more concise, readable, and efficient code. It is also a great way to learn about functional programming concepts.

I know Java Streams can be a bit daunting at first, but I created this article to help you get started. I’ll walk you through 15 coding questions that should help you deal with Java Streams.

By the end of this article, you’ll be able to:

Use Streams to solve common problems as a beginner
Write more concise and readable code
Have a good revision of Streams if you are an experienced developer.

If you are looking for in-depth understanding of Java Streams + LIVE code demo I have a 2-part video series, check out the links below:

Github documentation on Streams — https://github.com/VarshaDas/Java-Code-Snippets/blob/main/LambdasAndStreams/src/main/java/README-Streams.md

Relevant code links — https://github.com/VarshaDas/Java-Code-Snippets/tree/main/LambdasAndStreams/src/main/java

Now let’s start with the 15 Streams-based questions and their code snippets.

1. Find the sum of all even numbers in a list of integers.

2. Find and print the count of strings that have length greater than 5.

3. Implement a function that takes a list of integers as input and returns a new list containing the square of each element.

4. Find the maximum element in a list of integers.

5. Concatenate all the strings in a list into a single string.

6. Convert each string to uppercase and then sort them in alphabetical order.

7. Find the average of all the numbers in a list of doubles using Streams.

8. Create a new list that contains only unique words (remove duplicates).

9. Check if all elements in a List satisfy a given condition using streams.

10. Check if a list contains a specific element using streams.

11. Find the longest string in a list using streams.

12. Remove null values from a list using streams.

13. Problem Statement: GROUP BY Department and Find Max Salary

You have been tasked with analyzing a dataset of employee information to determine the maximum salary in each department. The dataset consists of a list of Employee objects, where each employee has a name, department, and salary. You need to group the employees by their respective departments and identify the maximum salary within each department.