👀 Views: 75 💬 Answers: 1 📅 Created: 2025-06-16

java sorting arrays comparator

I'm deploying to production and After trying multiple solutions online, I still can't figure this out. I'm relatively new to this, so bear with me. I'm encountering an issue when trying to sort an array of custom objects in Java. I have a class called `Person` that contains a `String name` and an `int age`. The goal is to sort an array of `Person` objects first by age (ascending) and then by name (alphabetically) if there are ties in age. However, when I use `Arrays.sort()` with a custom comparator, I'm getting inconsistent results. Sometimes, two `Person` instances with the same age seem to be sorted incorrectly by name. Here's the `Person` class: ```java public class Person { private String name; private int age; public Person(String name, int age) { this.name = name; this.age = age; } public String getName() { return name; } public int getAge() { return age; } } ``` And here’s how I’m trying to sort the array: ```java Person[] people = new Person[] { new Person("Alice", 30), new Person("Bob", 25), new Person("Charlie", 25), new Person("Dave", 30) }; Arrays.sort(people, new Comparator<Person>() { @Override public int compare(Person p1, Person p2) { int ageComparison = Integer.compare(p1.getAge(), p2.getAge()); if (ageComparison != 0) { return ageComparison; } else { return p1.getName().compareTo(p2.getName()); } } }); ``` After sorting, I am printing the sorted array: ```java for (Person person : people) { System.out.println(person.getName() + " - " + person.getAge()); } ``` In my tests, the output is sometimes: ``` Bob - 25 Charlie - 25 Alice - 30 Dave - 30 ``` But other times, it ends up as: ``` Charlie - 25 Bob - 25 Alice - 30 Dave - 30 ``` I did some debugging and verified that the `name` comparison is being reached for the tie cases. I’m using Java 11, and I’m not sure if there’s a specific reason for this inconsistent behavior. Is there something I’m missing in how I’m implementing the comparison, or is it related to how the sorting algorithm works? Any insights would be greatly appreciated! Any ideas what could be causing this? For context: I'm using Java on macOS. I'm coming from a different tech stack and learning Java.