Related Articles
Sorting a Hashmap according to values
• Difficulty Level : Hard
• Last Updated : 11 Dec, 2018

Given marks scored out of 100 by a student in subjects where name of the subject is key and marks scored is the value. Our task is to sort the hashmap according to values i.e. according to marks.

Example:

```Input : Key = Math, Value = 98
Key = Data Structure, Value = 85
Key = Database, Value = 91
Key = Java, Value = 95
Key = Operating System, Value = 79
Key = Networking, Value = 80

Output : Key = Operating System, Value = 79
Key = Networking, Value = 80
Key = Data Structure, Value = 85
Key = Database, Value = 91
Key = Java, Value = 95
Key = Math, Value = 98
```

Solution: The idea is to store the entry set in a list and sort the list on the basis of values. Then fetch values and keys from list and put them in new hashmap. Thus new hashmap is sorted according to values.

Below is implementation of the above idea:

 `// Java program to sort hashmap by values``import` `java.util.*;``import` `java.lang.*;`` ` `public` `class` `GFG {`` ` `    ``// function to sort hashmap by values``    ``public` `static` `HashMap sortByValue(HashMap hm)``    ``{``        ``// Create a list from elements of HashMap``        ``List > list =``               ``new` `LinkedList >(hm.entrySet());`` ` `        ``// Sort the list``        ``Collections.sort(list, ``new` `Comparator >() {``            ``public` `int` `compare(Map.Entry o1, ``                               ``Map.Entry o2)``            ``{``                ``return` `(o1.getValue()).compareTo(o2.getValue());``            ``}``        ``});``         ` `        ``// put data from sorted list to hashmap ``        ``HashMap temp = ``new` `LinkedHashMap();``        ``for` `(Map.Entry aa : list) {``            ``temp.put(aa.getKey(), aa.getValue());``        ``}``        ``return` `temp;``    ``}`` ` `    ``// Driver Code``    ``public` `static` `void` `main(String[] args)``    ``{`` ` `        ``HashMap hm = ``new` `HashMap();`` ` `        ``// enter data into hashmap``        ``hm.put(``"Math"``, ``98``);``        ``hm.put(``"Data Structure"``, ``85``);``        ``hm.put(``"Database"``, ``91``);``        ``hm.put(``"Java"``, ``95``);``        ``hm.put(``"Operating System"``, ``79``);``        ``hm.put(``"Networking"``, ``80``);``        ``Map hm1 = sortByValue(hm);`` ` `        ``// print the sorted hashmap``        ``for` `(Map.Entry en : hm1.entrySet()) {``            ``System.out.println(``"Key = "` `+ en.getKey() + ``                          ``", Value = "` `+ en.getValue());``        ``}``    ``}``}`

Output:

```Key = Operating System, Value = 79
Key = Networking, Value = 80
Key = Data Structure, Value = 85
Key = Database, Value = 91
Key = Java, Value = 95
Key = Math, Value = 98
```

Attention reader! Don’t stop learning now. Get hold of all the important Java Foundation and Collections concepts with the Fundamentals of Java and Java Collections Course at a student-friendly price and become industry ready. To complete your preparation from learning a language to DS Algo and many more,  please refer Complete Interview Preparation Course.

My Personal Notes arrow_drop_up