Generating Unique Random Numbers in Java

Summary: Learn how to generate unique random numbers efficiently in Java to ensure no repeats in your dataset, with practical code examples.
---

Generating Unique Random Numbers in Java

Creating unique random numbers in Java can be a common requirement in various applications such as generating unique IDs, random sampling for testing, and even for some gaming scenarios. In this guide, we will examine how to generate unique random numbers efficiently using Java.

Understanding the Basics

Method 1: Using a Set

One straightforward approach to achieve uniqueness is by leveraging a Set, which inherently does not allow duplicate elements. Here’s an example using HashSet:

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

In this code, the while loop keeps generating random numbers and adding them to the set until we have the desired number of unique numbers.

Method 2: Using a List and Shuffle

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

Here, we create a list containing numbers from 0 to bound - 1, shuffle the list to randomize the order, and then take a sublist of the desired size.

Method 3: Stream API

If you're using Java 8 or later, leveraging the Stream API can also be an elegant solution:

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

Conclusion

Generating unique random numbers in Java can be approached in various ways depending on the requirements and constraints. Using a Set is straightforward but may not be the most efficient for large datasets. Shuffling a list provides an interesting alternative that is easy to understand and implement. The Stream API offers a modern and concise method but requires understanding of streams and lambda expressions.

Choosing the right method depends on the specific use case and performance considerations. Hopefully, these examples provide a strong foundation to address your needs for generating unique random numbers in Java.