Home » Java » Core Java » Simplifying nested loops with Java 8 Lambdas

About Michael Scharhag

Michael Scharhag
Michael Scharhag is a Java Developer, Blogger and technology enthusiast. Particularly interested in Java related technologies including Java EE, Spring, Groovy and Grails.

Simplifying nested loops with Java 8 Lambdas

This is just a quick tip for everyone who often has to work with multi dimensional arrays in Java 8 (or newer).

In this case you might often end with code similar to this:

float[][] values = ...
for (int i = 0; i < values.length; i++) {
  for (int k = 0; k < values[i].length; k++) {
    float value = values[i][k];
    // do something with i, k and value
  }
}

If you are lucky you can replace the loops with for-each loops. However, often the indices are required for computations inside the loop.

In such a case you can come up with a simple utility method that looks like this:

private void loop(float[][] values, BiConsumer<Integer, Integer> consumer) {
  for (int i = 0; i < values.length; i++) {
    for (int k = 0; k < values[i].length; k++) {
      consumer.accept(i, k);
    }
  }
}

We can now loop over array indices like this:

float[][] values = ...
loop(values, (i, k) -> {
  float value = values[i][k];
  // do something with i, k and value
});

This way you can keep the looping code out of your main logic.

Of course you should change the shown loop() method so it fits your personal needs.

(0 rating, 0 votes)
You need to be a registered member to rate this.
1 Comment Views Tweet it!
Do you want to know how to develop your skillset to become a Java Rockstar?
Subscribe to our newsletter to start Rocking right now!
To get you started we give you our best selling eBooks for FREE!
1. JPA Mini Book
2. JVM Troubleshooting Guide
3. JUnit Tutorial for Unit Testing
4. Java Annotations Tutorial
5. Java Interview Questions
6. Spring Interview Questions
7. Android UI Design
and many more ....
I agree to the Terms and Privacy Policy

1
Leave a Reply

avatar
1 Comment threads
0 Thread replies
0 Followers
 
Most reacted comment
Hottest comment thread
1 Comment authors
Jade Recent comment authors

This site uses Akismet to reduce spam. Learn how your comment data is processed.

  Subscribe  
newest oldest most voted
Notify of
Jade
Guest
Jade

Hi Michael,

Thank you for this article. Is it possible to ask you an advice regarding nested for loop with java 8. Thank you very much. Jade