How to Sort an ArrayList of Custom Objects in Java by Property

Question

How can I sort an ArrayList of custom objects in Java based on a specific property?

public class Fruit {
    private String fruitName;
    private String fruitDesc;
    private int quantity;

    // Getters and setters
}

Answer

In Java, sorting an ArrayList of objects, such as a list of Fruit objects, can be achieved using the Collections.sort() method along with a custom Comparator. This allows you to define how the sorting should be performed, such as sorting by the fruit name in this case.

Collections.sort(fruits, new Comparator<Fruit>() {
    @Override
    public int compare(Fruit f1, Fruit f2) {
        return f1.getFruitName().compareTo(f2.getFruitName());
    }
});

Causes

  • Not implementing the Comparable interface for sorting.
  • Failing to use a Comparator for custom sorting logic.

Solutions

  • Use Collections.sort() with a custom Comparator to sort the ArrayList by the desired property, such as fruit name.
  • Consider implementing the Comparable interface in your class if natural ordering is preferred.

Common Mistakes

Mistake: Forgetting to import java.util.Collections and java.util.Comparator.

Solution: Ensure to import the required classes to use sort functionalities.

Mistake: Not providing getter methods for the properties used in comparison.

Solution: Ensure that the getter methods are correctly implemented to access properties.

Helpers

  • sort ArrayList Java
  • custom objects sorting Java
  • Java Collections sort
  • ArrayList sort by property

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