Differences between Comparable and Comparator

Summary

The video explains the differences between Comparable and Comparator in Java. It highlights that Comparable is used for default natural sorting, while Comparator allows for customized sorting. Key distinctions include their packages (`java.lang` for Comparable and `java.util` for Comparator), the number of methods each interface contains, and the classes that implement them. Comparable has a single method (`compareTo()`), whereas Comparator has two methods (`compare()` and `equals()`). This clear differentiation helps developers decide when to use each interface based on their sorting needs.

Takeaways

• 😀 Comparable is used for default natural sorting order.
• 😀 Comparator is used for customized sorting order.
• 📦 Comparable is found in the java.lang package.
• 📦 Comparator is found in the java.util package.
• 🔑 Comparable has one method: compareTo(T o).
• 🔑 Comparator has two methods: compare(T o1, T o2) and equals(Object obj).
• 🛠️ All wrapper classes and the String class implement Comparable.
• 🛠️ Few predefined classes, like Collator and RuleBasedCollator, implement Comparator.
• 📋 The main difference to remember: Comparable is for natural order, Comparator is for custom order.
• 💡 Use Comparable for a single sorting sequence and Comparator for multiple sorting sequences.

Q & A

What is the main purpose of the Comparable interface?

The Comparable interface is designed for defining a default natural sorting order for objects.

How does the Comparator interface differ from Comparable?

The Comparator interface allows for customized sorting orders, unlike Comparable which defines a natural order.

In which package is the Comparable interface located?

Comparable is located in the `java.lang` package.

Where can you find the Comparator interface?

The Comparator interface is found in the `java.util` package.

How many methods does the Comparable interface have, and what is it?

The Comparable interface has one method: `compareTo()`.

What methods are available in the Comparator interface?

The Comparator interface contains two methods: `compare()` and `equals()`.

Which classes implement the Comparable interface?

All wrapper classes and the String class implement the Comparable interface.

What are the primary classes that implement the Comparator interface?

The primary classes that implement Comparator are `Collator` and `RuleBasedCollator`.

When should you use Comparable instead of Comparator?

You should use Comparable when you want to define a natural order for objects; use Comparator when you need a custom order.

Why is the equals method often considered 'dummy' in the Comparator interface?

The equals method in the Comparator interface is often considered 'dummy' because it is not usually overridden and may not be relevant for comparison purposes.