Example
In this example we are gonna see how to check Key and value existence in Hashtable. We will be using following two methods to perform this check:
containsKey(Object key): To check if the key present in Hashtable.
containsvalue(Object value): To check if the value present in Hashtable.
import java.util.Hashtable;
public class CheckKeyValueExample {
public static void main(String[] args) {
// Creating a Hashtable instance
Hashtable<String, String> hashtable = new Hashtable<String, String>();
// Adding key-value pairs to Hashtable
hashtable.put("A", "Apple");
hashtable.put("B", "Orange");
hashtable.put("C", "Mango");
hashtable.put("D", "Banana");
hashtable.put("E", "Grapes");
/* Checking Key existence using containsKey() method.
* boolean containsKey(Object key) method returns true if the
* Hashtable contains the key, otherwise it returns false.
*/
boolean keyFlag1 = hashtable.containsKey("A");
System.out.println("Key A exists in Hashtable?: " + keyFlag1);
boolean keyFlag2 = hashtable.containsKey("D");
System.out.println("Key D exists in Hashtable?: " + keyFlag2);
boolean keyFlag3 = hashtable.containsKey("G");
System.out.println("Key G exists in Hashtable?: " + keyFlag3);
/* Checking Value existence using containsValue() method.
* boolean containsKey(Object key) method Returns true
* if this Hashtable maps one or more keys to this value..
*/
boolean vFlag1 = hashtable.containsValue("Orange");
System.out.println("Value Orange exists in Hashtable?: "+vFlag1);
boolean vFlag2 = hashtable.containsValue("XYZ");
System.out.println("Value XYZ exists in Hashtable?: "+vFlag2);
boolean vFlag3 = hashtable.containsValue("Apple");
System.out.println("Value Apple exists in Hashtable?: "+vFlag3);
}
}
Output:
Key A exists in Hashtable?: true Key D exists in Hashtable?: true Key G exists in Hashtable?: false Value Orange exists in Hashtable?: true Value XYZ exists in Hashtable?: false Value Apple exists in Hashtable?: true