Connection conn= DriverManager.getConnection("jdbc

dbc:sqlserver");
Statement st=conn.createStatement();
ResultSet rs=st.executeQuery("Select * from sysobjects");
in this, we know that Connection and Statements are Interface's , so how can the objects be created and referred by 'conn' and 'st' objects in the above example even though they are interfaces..
We know that for an interface only subclass objects can be referenced so what about the above case?...
the st.executeQuery() is just signature in the interface so,where is that methods functionality implemented...
Can some one help me in clarifing the doubt ..
i Will be very thankful to u if u help me about it...
Truly Friend ,
Awaiting for ur valuable replies..