Comparatorin Java

This class provides comparison logic based on the name. In such case, we are using the compareTo() method of String class, which internally provides the comparison logic.

Comparatorvs Comparable in Java

Collections class provides static methods for sorting the elements of a collection. If collection elements are of Set or Map, we can use TreeSet or TreeMap. However, we cannot sort the elements of List. Collections class provides methods for sorting the elements of List type elements also.

This class provides comparison logic based on the name. In such case, we are using the compareTo() method of String class, which internally provides the comparison logic.

Comparator comparatorjava

This interface is found in java.util package and contains 2 methods compare(Object obj1,Object obj2) and equals(Object element).

It provides multiple sorting sequences, i.e., you can sort the elements on the basis of any data member, for example, rollno, name, age or anything else.

Comparator comparatorexample

This class defines comparison logic based on the age. If the age of the first object is greater than the second, we are returning a positive value. It can be anyone such as 1, 2, 10. If the age of the first object is less than the second object, we are returning a negative value, it can be any negative value, and if the age of both objects is equal, we are returning 0.

Let's see the example of sorting the elements of List on the basis of age and name. In this example, we have created 4 java classes:

Java 8 Comparator interface is a functional interface that contains only one abstract method. Now, we can use the Comparator interface as the assignment target for a lambda expression or method reference.