Sorting a Custom Object ArrayList

Sort an ArrayList of custom objects in Java (Spring Boot compatible) using Comparator.

Method 1: Anonymous Comparator (concise)

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

class MyObject {
    String name;
    int value;
    // ... constructor, getters, setters ...
}

public class SortArrayList {
    public static void main(String[] args) {
        List<MyObject> list = new ArrayList<>();
        // ... populate list ...

        Collections.sort(list, Comparator.comparingInt(MyObject::getValue)); //ascending
        //Collections.sort(list, Comparator.comparingInt(MyObject::getValue).reversed()); //descending

        //Print sorted list
    }
}

Method 2: Named Comparator (for complex logic)

import java.util.Comparator;

class MyObjectComparator implements Comparator<MyObject> {
    @Override
    public int compare(MyObject o1, MyObject o2) {
        return Integer.compare(o1.getValue(), o2.getValue()); //ascending
        //return Integer.compare(o2.getValue(), o1.getValue()); //descending
    }
}

//In main method:
Collections.sort(list, new MyObjectComparator());

Key Considerations:

• Replace MyObject and getValue() with your actual class and property.
• Comparator.comparingInt is efficient for integer properties; use comparing for other types.
• .reversed() reverses the sorting order.
• For multiple sorting criteria, chain comparators using thenComparing. e.g., Comparator.comparing(MyObject::getName).thenComparingInt(MyObject::getValue)

This approach leverages Java's built-in sorting capabilities, making it efficient and readable. It's fully compatible with Spring Boot applications. Remember to handle potential NullPointerExceptions if your objects might have null property values.