Net hashtable key exists sql
I have hastable Hashtable hash = new Hashtable hash. Add( a, 1 hash. Add( b, 2 hash. Add( c, 3 hash. Add( c, 4 Now I need to check Key = c and value= 3 combination is already exits in hashtable or not. hash. Contains Key value function cheks weather key is exists or not and Contains Value function checks weather value is exists or not. But if I tried if( hash. Contains( c ) set; Type: System. Object The value associated with the specified key. If the specified key is not found, attempting to get it returns null, and attempting to set it creates a new element using the specified key. This property provides the ability to access a specific element in the collection by using the following syntax: my Collection[key]. You can also use the Item property to add new elements by setting the value of a key that does not exist in the Hashtable; for example, my Collection[ my Nonexistent Key ] = my Value. However, if the specified key already exists in the Hashtable, setting the Item property overwrites the old value. In contrast, the Add method does not modify existing elements. A key cannot be null, but a value can be. To distinguish between null that is returned because the specified key is not found and null that is returned because the value of the specified key is null, use the Contains method or the Contains Key method to determine if the key exists in the list. Retrieving the value of this property is an O(1) operation; setting the property is also an O(1) operation. The C language uses the keyword to define the indexers instead of implementing the Item property. Visual Basic implements Item as a default property, which provides the same indexing functionality. Universal Windows Platform Available since 10. NET Framework Available since 1.1 Add Hashtable Class System. Collections Namespace Return to top Show: Inherited Protected.
VB. NET: Keyword.
Check if a particular key exists in Java Hashtable example This Java Example shows how to check if Hashtable object contains a particular key using contains Key method of Hashtable class. import java.util. Hashtable; public class Check Key Of Hashtable Example public static void main( String[] args) /create Hashtable object Hashtable ht = new Hashtable /add key value pairs to Hashtable ht.put( 1, One ht.put( 2, Two ht.put( 3, Three To check whether a particular key exists in Hashtable use boolean contains Key( Object key) method of Hashtable class. It returns true if the Hashtable contains mapping for specified key otherwise false. boolean bln Exists = ht.contains Key( 2 System.out.println( 2 exists in Hashtable? : + bln Exists Output would be 2 exists in Hashtable? : true.