Comparable and Comparator Interfaces In Java - Differences and their use case
A General Introduction of Comparable and Comparators
Comparable and comparator are two different names for the same interface in the Java programming language. These interfaces are used to define the behavior of classes that are developed using Java. The Similar interface is utilized on items that already possess their own inherent ordering, whereas the Comparator interface is used to provide sorting by taking into account the properties of an object. In addition, the sorting done by Comparator takes into account objects of two distinct classes, whereas the Comparable method compares objects by referring to the "this" reference.
Let's have a look at the differences between the two interfaces now that we've determined the fundamental concept that underlies the operation of both of them. Explore more about Java by joining Java Training in Chennai.
When to Utilize Java's Comparable?
Comparing Comparable vs Comparator in Java, one of the most important things to keep in mind is knowing when it is appropriate to utilize Comparable. You need to go through a Similar interface selection process if you wish to sort the elements according to the default natural sorting order. The reason for this is that in order to use the natural sorting order that is the default, the object in question needs to be comparable as well as identical.
It is vital to keep in mind that an object is considered comparable if the Comparable interface is used by the class that the object belongs. Comparable functionality is included in each and every instance of the String and Wrapper classes by default. Because of this, implementing a Comparable interface is not necessary if you need to sort the String element in your application.
When to utilize a Java Comparator?
Comparable and comparator are two concepts that are used in Java, but they have quite different interfaces. If you want to avoid becoming confused, you need first learn the difference between comparable and comparator in Java. The order of the objects belonging to user-defined classes can be assisted thanks to the comparator interface.
Two objects that belong to the same class can each be compared by their respective comparator objects. For instance, you have an Array or ArrayList that represents a class and has fields such as name, address, roll number, date of birth, etc. You are going to want to sort the array based on either the name or the Roll number. At this stage in the Java tutorial, you will need to decide whether you will use a comparative or comparator. An ordered list of the objects that belong to a user-defined class can be generated with the use of a comparator interface.
When should you use a Comparable interface versus a Comparator interface while working in Java?
You have to be aware of the comparator interfaces as well as the similar interfaces, and you have to know which one to pick. It is recommended that you use the similar interface if you have a requirement that is fixed, such as the class objects being sorted based on a single field of the class, and also anticipate the same in the future and if this requirement will not change.
It is recommended to utilize the multiple comparator class directly if there is a necessity for sorting class objects through several fields. This requirement could arise if there is a need to sort class objects.
A comparator class offers flexibility, which means that you may construct several comparator classes and also use them to override things.
In addition, you can use the comparator classes to compare two different objects. On the other hand, an equivalent interface has been permanently implemented. While contrasting the functions of a comparable and comparator in Java, it is essential to keep this point in mind.
Comparison of Comparable and Comparator
Sorting Methods
Comparable
For sorting, it makes use of the compareTo() method. This method is the only one included in the Comparable sorting interface.
compareTo(Object O) compares one object to another of the same type given as an argument. You are only able to make a valid comparison between a string object and another object of the string type. The same is true for int objects and other similar objects.
Depending on the outcome of the sorting, compareTo() produces a negative, positive, or zero integer number.
This method returns an integer result that can be one of -1, 0, or 1.
If the value of this object is less than the value of the given object, the output is -1.
If the values of the supplied object and this object are equivalent, the output is 0.
If the value of this object is higher than the value of the given object, the output is 1.
Comparator
In Comparator, there are two ways to arrange elements: compare() and equals ().
You must be aware of when to utilize each comparator and comparable when comparing things. When you need a custom sorting order for the objects other than the natural ordering based on various fields, a comparator interface is typically utilized.
Taking into account two inputs as input, compare(Object O1, Object O2) produces the desired result. In order to compare the first and second arguments, it returns an integer.
If O1 is smaller than O2, a negative integer is returned.
A positive integer will be returned if O1 is bigger than O2.
O1 returns 0 if O2 is equal to it.
equals(Object) evaluates an object and compares it to the comparator while taking it into consideration as input. If the Object and the Comparator are equal, it returns True. Also, it guarantees that the sequence won't alter.
As for the syntax:
boolean equals(Object obj)
The object you wish to compare for equality, in this case, is obj. If both obj and the called object are Comparator objects and use the same ordering, this function returns true. Otherwise, false is returned.
Note: Since it serves no purpose, most simple comparators avoid overriding equals().
Type of Package Used
Comparable
It can be found in Java's java.lang package.
Comparator
It can be found in Java's java.util package.
Ordering and Classes
Comparable
It considers objects that naturally order themselves, or follow natural ordering. For instance, names, prices, salaries, roll numbers, ages, etc. could be arranged alphabetically or numerically.
The fact that both objects belong to the same class is also crucial.
The item supplied is compared with "this" reference using the Comparable interface.
Comparable sorting has an impact on the actual class.
Comparator
The main function of this interface is to sort the characteristics of the supplied objects. They can be tailored; a natural order is not required.
It is necessary to override the method comparison for the Comparator interface (obj).
To compare the attributes of the objects in the two classes under consideration, the sorting logic must be in distinct classes.
The actual class is not changed.
Collections and Sequences
Comparable
Just single sorting sequences are supported. This suggests that you can only take into account one component, such as a roll number, age, or rank when evaluating a collection.
Use Collection. sort(List) or Arrays. sort to order a collection of objects, arrays, or lists (List). The items will then be in their proper sequence as a result.
Comparator
It supports various sorting arrangements. This suggests that you can take into account a collection's numerous elements or features, such as a roll number, age, and rank.
To sort a collection, call collection.sort(list, comparator).
Additional distinctions between comparable and comparator
The fact that you can only utilize one comparison while using comparable is a key distinction between comparator and comparable. On the other side, you can create multiple custom comparators for a given type based on your requirements. In such a situation, each of the custom comparators will interpret sorting in a different way. For instance, whereas only one characteristic may be used to sort in the comparison example, multiple attributes can be used in the comparator.
Comparator and Comparable differ in another manner in that Comparator is utilized to provide many ways of sorting whereas Comparator is only capable of providing one. While utilizing Comparable, Class is necessary for implementation. On the other side, you don't need to change the class when using the Comparator. Comparators and comparables differ from one another in terms of how the interface is implemented.
All String classes and wrapper classes provide a similar interface. Moreover, bespoke items sort using a similar interface. On the other side, sorting custom objects is primarily done using the comparator interface. It can also be used to compare items from various classes.
Moreover, sorting objects in numerous fields are made easier by using the comparator interface, which highlights the major distinctions between comparables and comparators in Java.
Specification | Comparable | Comparator |
Package | Java.lang | Java.util |
Method of Sorting | compareTo() | compare() |
Ordering | Natural Ordering | Custom Ordering |
Type of Object | Objects in comparison must be of athe same type | Objects of different classes are considered |
Sorting Sequence | Single Sorting Sequence | Multiple Sorting Sequence |
Impact on Class | Class gets modified | Doesn’t affect the class, |
To Sum Up,
This was an in-depth look at Java's comparators and comparables. IBM-Certified Java Training in Chennai at SLA or a virtual class for this course is available at a reasonable price and comes with real-world projects, certification, placement assistance, career counseling support, and an active placement cell, preparing you to become a certified java developer in demand by employers.