Re: [newbe] casting at run time

From:
"polilop" <fmatosicSKINI@inet.hr>
Newsgroups:
comp.lang.java.programmer
Date:
Fri, 12 Jan 2007 08:13:06 +0100
Message-ID:
<eo7ce4$iuc$1@ss408.t-com.hr>
Sorry for me being hasty, here is the real code

public interface J2EEVo {
 public abstract boolean isSuccess();
 public abstract void setSuccess(boolean success);
}
public class UsersVo implements J2EEVo
{
  private String USERNAME;
 private String FAMILYNAME;
 private boolean success;

... a class constructor and set get methods
}
public class ReportVo implements J2EEVo
{
  private String HEADER;
 private String FOOTER;
 private boolean success;

... add class constructor and set get methods
}

public class ResultsetToVo {

 public J2EEVo fillVo(J2EEVo uvo,ResultSet rs) throws SQLException
 {
    if(uvo instanceof UsersVo) {
     uvo = (UsersVo)uvo;
    }
    else if(uvo instanceof ReportVo )
   {
        uvo=(ReportVo)uvo;
   }
  }

To answer Tom Hawtin: I am aware of instanceof, but is there another way to
cast the uvo at run time, so that i don't have to add a new if (uvo
insanceof someVo), every time a write a new J2EEVo that needs to use
ResultsetToVo. Something like (just a thought):

uvo =(getUvoClassInstance(uvo))uvo
Thanks

"Lew" <lew@nowhere.com> wrote in message
news:jP-dnY1Pvd-iRjvYnZ2dnUVZ_qbinZ2d@comcast.com...

polilop wrote:

class D
{

public doSomethingWithTypeA(A aClass)

/***So what i do is***/
if(B instanceof A)
cast A to B
if(C instanceof A)
cast A to C
}

main
B b=new B();
D d=new D();
d.doSomethingWithTypeA(b);


Your code as posted will not compile.

Create a real example. Try it before you post it.

You cannot invoke the "instanceof" operator with a type as the left
operand.

The variable name "aClass" is misleading since the variable is not of type
Class but of type A. It is bad practice to embed type information in a
variable name.

- Lew

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