Programming languages are always just a tool to achieve a goal. In reality, the entire syntax is quite simple, no matter what you’re learning. A few years ago, I decided to learn Java and start programming professionally in it. It was like opening Pandora’s box – all that weird and unoptimized stuff popped up, and it took me some time to find my way with Java. The syntax was easy after mastering Python. But then I was hit with Maven, Spring Boot, OOP, Design Patterns, and I wasn’t thrilled at all. Today, Java and I are old friends, and I’m okay with that. I quickly realized that my Java programs were slow and inefficient. Today, I’ll share a few ideas on how to optimize algorithms in Java.
1. Choose the Right Data Structures
Java collections are like a buffet – you have plenty to choose from, and if you combine some incorrectly, you’ll have a headache and stomachache. If you know you’ll be adding and removing elements from various places a lot, go for LinkedList. If you need something that can quickly look up elements, reach for HashMap or HashSet. And don’t forget about proper initialization! If you know how many items you plan to store, it’s better to set the size in advance – you’ll save memory and time.
Here are tips for selecting the right data structures:
- ArrayList: Great for quick access to elements but slower for adding or removing elements in the middle.
- LinkedList: Perfect for frequent additions and removals from any location but slower for accessing specific elements.
- HashMap: Excellent for quick lookups and storing key-value pairs.
- HashSet: Great for searching unique elements without duplicates.
- TreeMap: Use if you need to maintain the sorted order of keys.
This way, you won’t have a headache from collections, and your programs will run smoothly (of course, unless you spend hours debugging, which is the more likely scenario).
2. If Your Loops Are Running a Marathon, It’s Time to Give Them a Red Card
Or rather, optimize them? Honestly, I’ve never run a marathon, so I don’t really know how it works, so please forgive my clumsy phrasing and even worse attempt at a joke, dear IT world. Let’s get back to Java; it’s a little better for me. Has it ever happened to you that you were repeatedly calling the same method in a loop? Well, it has to me. If you know that the result doesn’t change, pull it out of the loop. And if you want to be really cool, try the Java Stream API. Not only is it functional, but when you use parallelStream(), you can significantly speed up calculations across multiple cores.
3. String Issues? Meet StringBuilder
Remember when you concatenated strings in a loop? I do… and never again! Use StringBuilder. Instead of creating millions of new objects with each string assignment, just create one and work with it. This will save you a lot of memory and time.
4. Memory is a Precious Resource, So Handle It Wisely
Avoid unnecessary object creation. If you can use primitive types, such as int
instead of Integer
, do it. And when you have data that frequently repeats, why not utilize caching? With a simple HashMap, you can store results of expensive operations and avoid recalculating them.
5. Parallelism? Maybe It Doesn’t Have to Be a Nightmare
If you have a task that can be broken down into smaller pieces, ExecutorService or ForkJoinPool are here to help you. They manage threads and distribute the work, so your processor will be working at full capacity without you having to worry about manually managing the threads.
6. Micro-optimizations Matter Too
I love the feeling of writing several if-else
blocks. My soul feels free, and I’m totally thrilled about it. Well, not really. So don’t be too proud of your multiple if-else
blocks, and if you can, do us all a favor and use switch. The computer will thank you, I will thank you, your colleague will thank you, and we’ll all think you’re a hero. Not really, but you’ll feel better about yourself.
Conclusion: Don’t Worry, Java is Your Friend
I’ve read a few unflattering things about Java several times. And I felt bad because poor Java isn’t to blame for anything. Perhaps after reading my article today, you’ll realize that you quite enjoy programming in Java because you now know a few strategies for optimization. Currently, I’m creating an application called Tasmag to manage my tasks. I’m really excited about it, but I’ll write about that another time.
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