casting interface to object.

[sreenivas jeenor]

Hi ,

i am working on this code.

how to achieve runtime casting for the following code

public interface Type extends Serializable{
 void clear();
 public String getName();
}

public interface Composite extends Type{
public Type[] getComponents();
public Type getComponent(int number);
}

public class Varies extends Object implements Type{

 /**
         * Returns the data contained by this instance of Varies. 
*/
        public Type getData() {
            return this.data;
        }

}


public class CWE implements Composite{

 public String getAlternateText(){
 Srtirng a ="NEW";
 return a;
 }
public Sting getText(){
 Srtirng b ="NEW";
 return b;
}

}

Similarly other classes like XPN, XCN implements composite.

in the Main file the code is..
-----------------------

Varies pm=new Varies();
	 pm.getData(); // how to cast to CWE or XPN or XCN  at runtime();

--------------------

help me...

[Hunter McMillen]

Have you tried:

Varies pm=new Varies(); 

cwe = (CWE)pm.getData();
xpn = (XPN)pm.getData();
xcn = (XCN)pm.getData();

Also, in your Varies class what is the type of 'data' that you return from getData()?

Hunter

[sreenivas jeenor]

Returns the data contained by this instance of Varies. Returns a GenericPrimitive unless setData() has been called.

[Hunter McMillen]

did the example code I posted work? was there an error?

Hunter

[Maneesh Godbole]

Sreenivas,
In future, while posting code, please UseCodeTags
I have edited and added them in your post. As you can see the tags make the code much more easy to read and understand.

[sreenivas jeenor]

private Type data;

here is

public class GenericComposite  implements Composite{
 /** Returns the name of the type (used in XML encoding and profile checking)  */
        public String getName() {
            return "UNKNOWN";
       }
    
           
          /**
             * {@inheritDoc }
            */
           public void clear() {
                   for (Type next : components) {
                          next.clear();
                   }
            }
}

its shows an error java.lang.ClassCastException: GenericComposite cannot be cast
to CWE

[Campbell Ritchie]

I would have thought that requiring so many casts implies a design error somewhere.

[Paul Clapham]

Campbell Ritchie wrote:I would have thought that requiring so many casts implies a design error somewhere.

To me that makes it look like the design should involve Generics in some way. Something perhaps like this:

public interface Composite<T extends Type> extends Type{  
public T[] getComponents();  
public T getComponent(int number);  
}  

[Campbell Ritchie]

Yes, Paul C, that looks a lot better.