Sort LinkedHashMap by Values using Comparable Interface in Java
Last Updated :
13 Jan, 2021
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The LinkedHashMap is just like HashMap with an additional feature of maintaining an order of elements inserted into it. Assuming you have gone through LinkedHashMap in java and know about LinkedHashMap.
Syntax:
int compare(T obj) ;
Illustration:
Input : { GEEKS=1, geeks=3, for=2 }
Output : { GEEKS=1, for=2, geeks=3 }
Input : { 101 = 2, 102 = 9, 103 = 1, 105 = 7 }
Output : { 103 = 1, 101 = 2, 105 = 7, 102 = 9 }
Method: While using Comparable interface to sort LinkedHashMap by value, this interface imposes a total ordering on the objects of each class that implements it. This ordering refers to as the class’s natural ordering and the class’s comparator method is referred to as its natural comparison method.
Implementation:
Example
Java
// Java program to sort the values of LinkedHashMap // Importing required classes from // java.util package import java.util.*; import java.util.ArrayList; import java.util.Collections; import java.util.Comparator; import java.util.LinkedHashMap; import java.util.List; import java.util.Map.*; // Class public class GFG { // Main driver method public static void main(String[] args) { // Creating an LinkedHashMap object LinkedHashMap<String, Integer> l_map = new LinkedHashMap<String, Integer>(); // Adding element to LinkedHashSet // Custom inputs l_map.put("Computer", 1); l_map.put("Science", 3); l_map.put("Portal", 2); // Display message System.out.print( "LinkedHashMap without sorting : "); // Print the elements of Map in above object // just after addition without sorting System.out.println(l_map); // Convert key-value from the LinkedHashMap to List // using entryset() method List<Map.Entry<String, Integer> > list = new ArrayList<Map.Entry<String, Integer> >( l_map.entrySet()); // Comparable Interface function to // sort the values of List Collections.sort( list, new Comparator<Map.Entry<String, Integer> >() { // Comparing entries public int compare( Entry<String, Integer> entry1, Entry<String, Integer> entry2) { return entry1.getValue() - entry2.getValue(); } }); // Clear the above LinkedHashMap // using clear() method l_map.clear(); // Iterating over elements using for each loop for (Map.Entry<String, Integer> entry : list) { // Put all sorted value back to the // LinkedHashMap l_map.put(entry.getKey(), entry.getValue()); } // Display and print // the sorted value of LinkedHashMap System.out.println( "LinkedHashMap after sorting : " + l_map); } } |
Output
LinkedHashMap without sorting : {Computer=1, Science=3, Portal=2}
LinkedHashMap after sorting : {Computer=1, Portal=2, Science=3}
