Java Collection, HashMap Exercises: Test if a map contains a mapping for the specified value

Java Collection, HashMap Exercises: Exercise-8 with Solution

Write a Java program to test if a map contains a mapping for the specified value.

Sample Solution:-

Java Code:

import java.util.*;  
public class Example8 {  
   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");
  // print the map
  System.out.println("The Original map: " + hash_map);
  System.out.println("1. Is value \'Green\' exists?");
  if (hash_map.containsValue("Green")) {
   //value exists
   System.out.println("Yes! ");
  } else {
   //value does not exists

  System.out.println("\n2. Is value \'orange\' exists?");
  if (hash_map.containsValue("orange")) {
   System.out.println("yes! - " );
  } else {

Sample Output:

The Original map: {1=Red, 2=Green, 3=Black, 4=White, 5=Blue}           
1. Is value 'Green' exists?                                            
2. Is value 'orange' exists?                                           

Java Code Editor:

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Java: Tips of the Day


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