Java: Test if a map contains a mapping for the specified key

Last update on May 22 2025 13:15:28 (UTC/GMT +8 hours)

7. Check If Key Exists in Map

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

Sample Solution:-

Java Code:

import java.util.*;  
public class Example7 {  
   public static void main(String args[]) {
  HashMap < String, Integer > hash_map = new HashMap < String, Integer > ();
  hash_map.put("Red", 1);
  hash_map.put("Green", 2);
  hash_map.put("Black", 3);
  hash_map.put("White", 4);
  hash_map.put("Blue", 5);
  // print the map
  System.out.println("The Original map: " + hash_map);
  System.out.println("1. Is key 'Green' exists?");
  if (hash_map.containsKey("Green")) {
   //key exists
   System.out.println("yes! - " + hash_map.get("Green"));
  } else {
   //key does not exists
   System.out.println("no!");
  }

  System.out.println("\n2. Is key 'orange' exists?");
  if (hash_map.containsKey("orange")) {
   System.out.println("yes! - " + hash_map.get("orange"));
  } else {
   System.out.println("no!");
  }
 }
}

Sample Output:

The Original map: {Red=1, White=4, Blue=5, Black=3, Green=2}           
1. Is key 'Green' exists?                                              
yes! - 2                                                               
                                                                       
2. Is key 'orange' exists?                                             
no!

For more Practice: Solve these Related Problems:

Write a Java program to check if a HashMap contains a specific key using containsKey() and print a custom message.
Write a Java program to use Java streams to filter a map’s key set for a given key and return a boolean result.
Write a Java program to iterate over a map and manually check for the existence of a key, then print the result.
Write a Java program to implement a method that checks if a key is present in a map and returns its associated value if found.

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Java Code Editor:

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