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Java Program to Sort map by keys

Java Program to Sort map by keys

In this example, we will learn to sort the map by keys in Java.

To understand this example, you should have the knowledge of the following Java programming topics:


Example: Sort a map by keys using TreeMap

import java.util.HashMap;
import java.util.Map;
import java.util.TreeMap;

class Main {
  public static void main(String[] args) {

    // create a hashmap
    Map<String, String> languages = new HashMap<>();
    languages.put("pos3", "JS");
    languages.put("pos1", "Java");
    languages.put("pos2", "Python");
    System.out.println("Map: " + languages);

    // create a tree map from the map
    TreeMap<String, String> sortedNumbers = new TreeMap<>(languages);
    System.out.println("Map with sorted Key" + sortedNumbers);

  }
}

Output

Map: {pos1=Java, pos2=Python, pos3=JS}
Map with sorted Key{pos1=Java, pos2=Python, pos3=JS}

In the above example, we have created a map named languages using HashMap. Here, the map is not sorted.

To sort the map, we created a treemap from the map. Now, the map is sorted by its keys.