What are the differences between Comparator and Comparable interfaces in Java?

In Java, the interfaces Comparable and Comparator are used for comparing objects but serve different purposes:

• Comparable — defines the natural order of objects. A class implements this interface so that objects can be compared with each other using the compareTo() method. It is typically used for default sorting.

• Comparator — a separate object that defines an alternative way of comparing two objects. It is used when you need to sort objects by different criteria or when a class does not implement Comparable.

Example:

class Person implements Comparable<Person> {
    String name;
    int age;

    public int compareTo(Person other) {
        return this.name.compareTo(other.name); // natural order by name
    }
}

// Comparator for sorting by age
Comparator<Person> ageComparator = new Comparator<Person>() {
    public int compare(Person p1, Person p2) {
        return Integer.compare(p1.age, p2.age);
    }
};

Thus, Comparable sets a single comparison method within the class, while Comparator allows creating multiple external comparison methods.