SortedMap comparator() method in Java with Examples - GeeksforGeeks

08 Jun, 2021
The comparator() method of java.util.SortedMap interface is used to return the comparator used to order the keys in this map, or null if this map uses the natural ordering of its keys.Syntax:  
public Comparator comparator()
Return Value: This method returns the comparator used to order the keys in this map, or null if this map uses the natural ordering of its keys.Below programs illustrate the comparator() method:Example 1: For Natural ordering.  
Java
// Java program to demonstrate// comparator() method for natural ordering import java.util.*; public class GFG1 {    public static void main(String[] argv)        throws Exception    {         try {             // Creating object of SortedTreeMap            SortedMap<Integer, String>                sotreemap = new TreeMap<Integer, String>();             // Populating tree map            sotreemap.put(1, "one");            sotreemap.put(2, "two");            sotreemap.put(3, "three");            sotreemap.put(4, "four");            sotreemap.put(5, "five");             // Printing the SortedTreeMap            System.out.println("SortedTreeMap: " + sotreemap);             // Getting used Comparator in the map            // using comparator() method            Comparator comp = sotreemap.comparator();             // Printing the comparator value            System.out.println("Comparator value: "                               + comp);        }         catch (NullPointerException e) {            System.out.println("Exception thrown : " + e);        }    }}
SortedTreeMap: {1=one, 2=two, 3=three, 4=four, 5=five}
Comparator value: null
 
Example 2: For Reverse ordering.  
Java
// Java program to demonstrate// comparator() method// for reverse ordering import java.util.*; public class GFG1 {    public static void main(String[] argv)        throws Exception<div class="code-output"><b>Output:</b><pre>Initial Mappings are: {10=Geeks, 15=4, 20=Geeks, 25=Welcomes, 30=You}The set is: [10=Geeks, 15=4, 20=Geeks, 25=Welcomes, 30=You]</pre></div>     {         try {             // Creating object of TreeMap            SortedMap<Integer, String>                sotreemap = new TreeMap<Integer, String>(                    Collections.reverseOrder());             // Populating tree map            sotreemap.put(1, "one");            sotreemap.put(2, "two");            sotreemap.put(3, "three");            sotreemap.put(4, "four");            sotreemap.put(5, "five");             // Printing the TreeMap            System.out.println("SortedTreeMap: " + sotreemap);             // Getting used Comparator in the map            // using comparator() method            Comparator comp = sotreemap.comparator();             // Printing the comparator value            System.out.println("Comparator value: " + comp);        }         catch (NullPointerException e) {            System.out.println("Exception thrown : " + e);        }    }}
SortedTreeMap: {5=five, 4=four, 3=three, 2=two, 1=one}
Comparator value: java.util.Collections$ReverseComparator@232204a1
 
anikakapoor
Java - util package
Java-Collections
Java-Functions
Java-SortedMap
Java
Java
Java-Collections
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