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Check if a particular key exists in Java HashMap example

  1. /*
  2.   Check if a particular key exists in Java HashMap example
  3.   This Java Example shows how to check if HashMap object contains a particular
  4.   key using containsKey method of HashMap class.
  5. */
  6.  
  7. import java.util.HashMap;
  8.  
  9. public class CheckKeyOfHashMapExample {
  10.  
  11.   public static void main(String[] args) {
  12.    
  13.     //create HashMap object
  14.     HashMap hMap = new HashMap();
  15.    
  16.     //add key value pairs to HashMap
  17.     hMap.put("1","One");
  18.     hMap.put("2","Two");
  19.     hMap.put("3","Three");
  20.    
  21.     /*
  22.       To check whether a particular key exists in HashMap use
  23.       boolean containsKey(Object key) method of HashMap class.
  24.       It returns true if the HashMap contains mapping for specified key
  25.       otherwise false.
  26.     */
  27.    
  28.     boolean blnExists = hMap.containsKey("3");
  29.     System.out.println("3 exists in HashMap ? : " + blnExists);
  30.   }
  31. }
  32.  
  33. /*
  34. Output would be
  35. 3 exists in HashMap ? : true
  36. */