Java Collection How to - Check if a particular key/value exists in HashMap

Question

We would like to know how to check if a particular key/value exists in HashMap.

Answer

//from   w w  w .ja va 2  s  . c  o  m
import java.util.HashMap;

public class Main {
  public static void main(String[] args) {
    HashMap<String, String> hMap = new HashMap<String, String>();

    hMap.put("1", "One");
    hMap.put("2", "Two");
    hMap.put("3", "Three");

    boolean blnExists = hMap.containsKey("3");
    System.out.println("3 exists in HashMap ? : " + blnExists);
  }
}

The code above generates the following result.

//from  ww  w  .jav  a  2s . com
import java.util.HashMap;

public class Main {
  public static void main(String[] args) {
    HashMap<String, String> hMap = new HashMap<String, String>();

    hMap.put("1", "One");
    hMap.put("2", "Two");
    hMap.put("3", "Three");

    System.out.println(hMap.containsValue("Two"));
  }
}

The code above generates the following result.