What is difference between comparable and Comparator interface in Java?

Comparable in Java is an object to compare itself with another object, whereas Comparator is an object for comparing different objects of different classes. Comparable provides compareTo() method to sort elements in Java whereas Comparator provides compare() method to sort elements in Java.

What is the difference between comparable interface and Comparator interface?

Comparator interface belongs to java. util package while comparable belongs to java. lang package. Comparator interface sort collection using two objects provided to it, whereas comparable interface compares" this" refers to the one objects provided to it.

What is the main difference between comparable and Comparator?

While Comparable is used on objects that are naturally ordered, the Comparator interface implements sorting by taking the attributes of an object into consideration. Further, Comparator sorting takes into account objects of two different classes and Comparable compares objects using the “this” reference.

What is comparable and Comparator interface explain with example?

Logically, Comparable interface compares “this” reference with the object specified and Comparator in Java compares two different class objects provided. If any class implements Comparable interface in Java then collection of that object either List or Array can be sorted automatically by using Collections.

Which is better Comparator or comparable in Java?

Comparable should be used when you compare instances of the same class. Comparator can be used to compare instances of different classes. Comparable is implemented by the class which needs to define a natural ordering for its objects. For example, String implements Comparable.

Differences between Comparable and Comparator

What is Comparator interface used for?

A comparator interface is used to order the objects of user-defined classes. A comparator object is capable of comparing two objects of the same class.

Is Comparator a functional interface?

Answer. Yes, Comparator is a functional interface. The equals is an abstract method overriding one of the public methods of java. lang.

What is Comparator interface Java?

Java Comparator is an interface for sorting Java objects. Invoked by “java. util. comparator,” Java Comparator compares two Java objects in a “compare(Object 01, Object 02)” format. Using configurable methods, Java Comparator can compare objects to return an integer based on a positive, equal or negative comparison.

What is Java comparable interface?

The Java Comparable interface, java. lang. Comparable , represents an object which can be compared to other objects. For instance, numbers can be compared, strings can be compared using alphabetical comparison etc. Several of the built-in classes in Java implements the Java Comparable interface.

What is the difference between comparable and Comparator in Java util package?

Comparable in Java is an object to compare itself with another object, whereas Comparator is an object for comparing different objects of different classes. Comparable provides compareTo() method to sort elements in Java whereas Comparator provides compare() method to sort elements in Java.

Why Comparator is used in Java?

Java Comparator interface is used to order the objects of a user-defined class. This interface is found in java. util package and contains 2 methods compare(Object obj1,Object obj2) and equals(Object element).

What is difference between compare and compareTo in Java?

compareTo(b) : Comparable interface : Compares values and returns an int which tells if the values compare less than, equal, or greater than. compare(a, b) : Comparator interface : Compares values of two objects.

What is difference between list and set?

List is an ordered sequence of elements whereas Set is a distinct list of elements which is unordered. List <E>: An ordered collection (also known as a sequence). The user of this interface has precise control over where in the list each element is inserted.

What is the difference between ArrayList and Vector in Java?

ArrayList is non-synchronized. Vector is synchronized. ArrayList increments 50% of its current size if element added exceeds its capacity. Vector increments 100% of its current size if element added exceeds its capacity.

Is comparable an interface or class?

The Comparable interface defines the compareTo method used to compare objects. If a class implements the Comparable interface, objects created from that class can be sorted using Java's sorting algorithms.

What is the comparable class in Java?

Java Comparable interface is used to order the objects of the user-defined class. This interface is found in java. lang package and contains only one method named compareTo(Object). It provides a single sorting sequence only, i.e., you can sort the elements on the basis of single data member only.

What is a TreeSet?

TreeSet is one of the most important implementations of the SortedSet interface in Java that uses a Tree for storage. The ordering of the elements is maintained by a set using their natural ordering whether or not an explicit comparator is provided.

What is difference between ArrayList and LinkedList?

ArrayList internally uses a dynamic array to store its elements. LinkedList uses Doubly Linked List to store its elements. ArrayList is slow as array manipulation is slower. LinkedList is faster being node based as not much bit shifting required.

How does a comparable and comparator work internally?

In Java, Comparable and Comparator are used for sorting collection of objects. java. lang. Comparable is used to sort collection of same types(classes) like List<Student>, List<Employee>, List<Orange>, It means Comparable is like "I can compare myself with another object of same type".

Can we iterate HashMap?

There is a numerous number of ways to iterate over HashMap of which 5 are listed as below: Iterate through a HashMap EntrySet using Iterators. Iterate through HashMap KeySet using Iterator. Iterate HashMap using for-each loop.

Can we have 2 abstract methods in functional interface?

A functional interface is an interface that contains only one abstract method. They can have only one functionality to exhibit.

What is Sam interface?

An interface with only one abstract method is called a functional interface, or a Single Abstract Method (SAM) interface. The functional interface can have several non-abstract members but only one abstract member.

Why Comparator interface has Equals method?

Comparator refines the contract of Object. equals : It has to satisfy the constraints set out by Object. equals and then some. Additionally, this method can return true only if the specified object is also a comparator and it imposes the same ordering as this comparator.