Mastering Java: Sorting ArrayLists of Custom Objects with Ease
Understanding the Basics
To grasp this example, you should be familiar with Java classes and objects, as well as ArrayLists. If you’re new to these concepts, take a moment to review them before diving in.
The CustomObject Class: A Closer Look
Let’s examine the CustomObject class, which boasts a String property called customProperty. This property is initialized via a constructor and can be accessed using the getCustomProperty() method. Simple, yet effective!
Sorting Magic: Unleashing the Power of Lambda
Now, let’s focus on the main() method, where the real action happens. We create an ArrayList, aptly named list, and populate it with five custom objects. But here’s the fascinating part: we use the sort() method to sort this list based on the customProperty.
The Lambda Comparator: A Game-Changer
So, how does this sorcery work? The lambda comparator takes two objects, o1 and o2, from the list and compares their customProperty values using the compareTo() method. This comparison yields one of three results:
- A positive number if o1’s property is greater than o2’s
- A negative number if o1’s property is lesser than o2’s
- Zero if they’re equal
Based on these results, the list is sorted from least to greatest and stored back in the original list. Note that for int properties, you can use Comparator.comparingInt(CustomObject::getCustomProperty) to achieve the same effect.
Putting it all Together
With these concepts in place, you’re now equipped to sort ArrayLists of custom objects like a pro! Remember, practice makes perfect, so don’t be afraid to experiment and push the boundaries of what’s possible with Java.