Java Program to Sort a Map By Values
Java Map Interface
The Map interface also provides methods for checking the presence of a key, getting the size of the Map, and iterating over the Map to process its key-value pairs.
- Map is a generic interface, declared as Map<K, V>.
- A Map cannot contain duplicate keys. Each key can map to at most one value.
To know more about Java Program to Sort map by Values read the complete article.
Steps for Program to Sort a Map By Values:
- Convert the Map into a Stream.
- Sort the stream using the sorted method with a custom Comparator that compares the Map values.
- Collect the sorted stream into a new Map using the collect method and toMap collector with the original Map’s keys and values.
- Return the newly sorted Map.
Java Map Interface:
- Some common implementations of the Map interface include java.util.HashMap, java.util.TreeMap, and java.util.LinkedHashMap. Each implementation has different performance characteristics and use cases, but they all provide the same basic Map functionality.
Java LinkedHashMap:
- java.util.Linked Java's HashMap class extends the java.util.HashMap class and implements the java.util.Map interface. To retain the order of the elements added into the map, it uses a doubly-linked list.
Let’s look at a Java Program to Sort map by Values to perform certain operations .
Example 1: Java Program to Sort a Map By Values
import java.util.*;
public class Main {
public static void main(String[] args) {
Map<String, Integer> map = new HashMap<>();
map.put("Ashish", 3);
map.put("Ananya", 2);
map.put("Ayush", 1);
map.put("Aryan", 4);
List<Map.Entry<String, Integer>> list = new ArrayList<>(map.entrySet());
list.sort(Map.Entry.comparingByValue());
System.out.println("Sorted Map by Values: " + list);
}
}
Output
Sorted Map by Values: [Ayush=1, Ananya=2, Ashish=3, Aryan=4]
Explanation:
- Create a Map object and add key-value pairs to it.
- Create a List of Map.Entry from the Map and sort the list using List.sort and Map.Entry.comparingByValue.
- The sorted List can be printed as the output.
Example 2 :Java Program to Sort a Map By Values
import java.util.*;
public class Main {
public static void main(String[] args) {
Map<String, Integer> map = new HashMap<>();
map.put("Hyundai", 15);
map.put("Maruti", 40);
map.put("Honda", 10);
map.put("Tata", 25);
map.put("Kia", 5);
map.put("Mahindra", 8);
List<Map.Entry<String, Integer>> list = new ArrayList<>(map.entrySet());
list.sort(Map.Entry.comparingByValue());
System.out.println("Sorted Map by Values: " + list);
}
}
Output
Sorted Map by Values: [Kia=5, Mahindra=8, Honda=10, Hyundai=15, Tata=25, Maruti=40]
Explanation:
A Map object is created and populated with key-value pairs, where the keys are String values and the values are Integer values.
The Map is then converted to a List of Map.Entry objects using the entrySet method.
The List is sorted using the List.sort method and the Map.Entry.comparingByValue method.
The sorted List is then printed as the output.
Example 3: Java Program to sort a map by Values.
import java.util.*;
public class Main {
public static void main(String[] args) {
Map<String, Integer> map = new HashMap<>();
map.put("Alex", 50);
map.put("Bob", 60);
map.put("Charlie", 70);
map.put("David", 80);
List<Map.Entry<String, Integer>> list = new ArrayList<>(map.entrySet());
list.sort(Map.Entry.<String, Integer>comparingByValue().reversed());
System.out.println("Sorted Map by Values in Descending Order: " + list);
}
}
Output
Sorted Map by Values in Descending Order: [David=80, Charlie=70, Bob=60, Alex=50]
Explanation:
- This code sorts a Map of
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