Java Comparator and Comparable interfaces explained with examples in simple terms
In Java, we come across a list of objects like all employees or all students etc. Many a times, it is required to sort them for customization. For example, a student may be required to sort by his roll number, name or marks etc. To sort the objects, Java comes with two interfaces – java.lang.Comprable …
Before going through this program, it is advised to go through the interface Comparable tutorial. In the following Employee program, compareTo() method of Comparable interface is used to sort the employees by their ages. To use the compareTo() method, Employee class implements Comparable interface. Example code on Comparable Example import java.util.*; class Employee implements Comparable …
Comparator interface is from java.util package like other data structures. Some data structures TreeSet and TreeMap sort the elements in natural (ascending) order by default. The Comparator object is capable to change this order, the way customization requires. Programmer can get a precise control over ordering. In Java, we come across a list of objects …
After knowing the fundamentals of interface Comparator, let us make a small example. ArrayList elements are printed in reverse order using Comparator. Example code on Comparator Example Java import java.util.*; public class ComparatorExample { public static void main(String args[]) { ArrayList stones = new ArrayList(); stones.add(“pearl”); stones.add(“diamond”); stones.add(“ruby”); stones.add(“emerald”); stones.add(“topaz”); Comparator comp1 = Collections.reverseOrder(); System.out.println(“Default …
At the outset, both are used for ordering the elements of a data structure in the way the programmer desires. Just they differ in their methods of implementation and usage with objects in comparison. These two interfaces are best suitable for ordering the objects depending on their fields. For example, student objects can be ordered …
