Given a map in Java, the task is to find out the entry in this map with the highest value.
Illustration:
Input : Map = {ABC = 10, DEF = 30, XYZ = 20}
Output : DEF = 30
Input : Map = {1 = 40, 2 = 30, 3 = 60}
Output : 3 = 60
Methods: There can be several approaches to achieve the goal that are listed as follows:
- Simple iterative approach via for each loop
- Using max() method from Collections class
- Using the concept of Streams introduced in Java 8
Now we will discuss the above-proposed methods alongside procedure and implementing them via clean java programs.
Method 1: Using iterative approach for each loop
Approach:
- Iterate the map entry by entry
- Store the first entry in a reference variable to compare to initially.
- If the current entry’s value is greater than the reference entry’s value, then store the current entry as the reference entry.
- Repeat this process for all the entries in the map.
- In the end, the reference variable has the required entry with the highest value in the map.
- Print this entry
for (Map.Entry entry : map.entrySet())
{ // Operations }
Example:
Java
// Java program to Find Entry// with the Highest Value in Map// Using Comparators in Map interface// Importing all utility classesimport java.util.*;// Main classclass GFG { // Method 1 // Find the entry with highest value public static <K, V extends Comparable<V> > Map.Entry<K, V> getMaxEntryInMapBasedOnValue(Map<K, V> map) { // To store the result Map.Entry<K, V> entryWithMaxValue = null; // Iterate in the map to find the required entry for (Map.Entry<K, V> currentEntry : map.entrySet()) { if ( // If this is the first entry, set result as // this entryWithMaxValue == null // If this entry's value is more than the // max value Set this entry as the max || currentEntry.getValue().compareTo( entryWithMaxValue.getValue()) > 0) { entryWithMaxValue = currentEntry; } } // Return the entry with highest value return entryWithMaxValue; } // Method 2 // To print the map public static void print(Map<String, Integer> map) { System.out.print("Map: "); // If map does not contain any value if (map.isEmpty()) { System.out.println("[]"); } else { System.out.println(map); } } // Method 3 // Main driver method public static void main(String[] args) { // Creating a Map // Declaring object of string and integer type Map<String, Integer> map = new HashMap<>(); // Inserting elements in the Map object // using put() method // Custom input element addition map.put("ABC", 10); map.put("DEF", 30); map.put("XYZ", 20); // Calling method 2 to // print the map print(map); // Calling method 1 to // find the entry with highest value and // print on the console System.out.println( "Entry with highest value: " + getMaxEntryInMapBasedOnValue(map)); }} |
Output:
Map: {ABC=10, DEF=30, XYZ=20}
Entry with highest value: DEF=30
Method 2: Using max() method from Collections class without lambda expression
Example:
Java
// Java Program to Find Entry with largest Value in Map// Using max() method from Collections class// Importing required classesimport java.util.*;// main classclass GFG { // Main driver method public static void main(String[] args) { // Creating HashMap // Declaring objects of string and integer type HashMap<Integer, Integer> map = new HashMap<Integer, Integer>(); // Inserting elements in the Map // using put() method // Custom input addition map.put(1, 4); map.put(2, 5); map.put(3, 7); map.put(4, 2); // Using Collections.max() method returning max // value in HashMap and storing in a integer // variable int maxValueInMap = (Collections.max(map.values())); // Iterate through HashMap for (Entry<Integer, Integer> entry : map.entrySet()) { if (entry.getValue() == maxValueInMap) { // Print the key with max value System.out.println(entry.getKey()); } } }} |
Output:
3
Method 3: Using the concept of Streams introduced in Java 8
Java
// Java Program to Find Entry with largest Value in Map// Using concept of Streamsimport java.util.stream.*;// Main classclass GFG { // Method 1 public static void main(String[] args) { // Entries in our map Map<String, String> map = new HashMap<>(); map.put("A", "23"); map.put("F", "43"); map.put("C", "56"); map.put("Z", "04"); // Printing the largest value in map by // calling above method System.out.print(map.maxUsingStreamAndLambda()); } // Method 2 public <String, String> extends Comparable<String> > maxUsingStreamAndLambda( Map<String, String> map) { // Using lambda operation over streams Map<String, String> maxEntry = map.entrySet().stream().max( (String e1, String e2) -> e1.getValue().compareTo( 0e2.getValue())); // Returning the maximum element from map return maxEntry.get().getValue(); }} |
Output:
C
