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Java Collection, HashMap Exercises: Check whether a map contains key-value mappings (empty) or not

Java Collection, HashMap Exercises: Exercise-5 with Solution

Write a Java program to check whether a map contains key-value mappings (empty) or not.

Sample Solution:-

Java Code:

import java.util.*;  
public class Example5 {  
   public static void main(String args[]) {
  HashMap <Integer,String> hash_map = new HashMap <Integer,String> ();
  hash_map.put(1, "Red");
  hash_map.put(2, "Green");
  hash_map.put(3, "Black");
  hash_map.put(4, "White");
  hash_map.put(5, "Blue");
  // check if map is empty
  boolean result = hash_map.isEmpty();
  // check the result
  System.out.println("Is hash map empty: " + result);
  // Removing all the elements from the linked map
  hash_map.clear();
  // check if map is empty
  result = hash_map.isEmpty();
  // check the result
  System.out.println("Is hash map empty: " + result);
 }
}

Sample Output:

Is hash map empty: false                                               
Is hash map empty: true

Java Code Editor:

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Java: Tips of the Day

getEnumMap

Converts to enum to Map where key is the name and value is Enum itself.

public static <E extends Enum<E>> Map<String, E> getEnumMap(final Class<E> enumClass) {
    return Arrays.stream(enumClass.getEnumConstants())
            .collect(Collectors.toMap(Enum::name, Function.identity()));
}

Ref: https://bit.ly/3xXcFZt