java - I am Always getting the Instance of Parent Class.But i need a child one -

i want instance of child class getting parent class instance can explain me why?? according xmltype id getting instace of children(string or anyuri) etc.but in conditions need child class instance.

code::

public abstract class wstype       public final static wstype getinstance(int xmltypeid) {         switch (xmltypeid) {         case string: return wsstringtype2.getinstance(); //**here getting parent class  calling instance of wsstringtype2.**         case anyuri: return wsanyuritype2.getinstance();         }     }      public final static wstype getinstance(int xmltypeid, string data) throws xcallexception {         wstype wsdata = wstype.getinstance(xmltypeid); /**/calling happening here**    }      } public class wsstringtype extends wstype {      protected string m_data;       public wsstringtype() { m_data = "'"; }     public wsstringtype(string name){ m_data=name; }      public static wsstringtype getinstance() {         return new wsstringtype();     }   } class wsstringtype2 extends wsstringtype {     public wsstringtype2() { m_data = "'"; }    public static wsstringtype2 getinstance() {         return new wsstringtype2();     }     public wsstringtype2(string newvalue){          super(newvalue);    }   } 

the return type of getinstance(int xmltypeid) wstype parent. can cast wsstringtype2 because wsstringtype2 extends wsstringtype , wsstringtype extends wstype

wstype wt = wstype.getinstance(string); wsstringtype2 wt2 = null; if (t instanceof wsstringtype2) {     wt2 = (wsstringtype2) wt; }