Re: Instanceof design doubt in Java

From:
Lothar Kimmeringer <news200709@kimmeringer.de>
Newsgroups:
comp.lang.java.help
Date:
Tue, 15 Feb 2011 18:40:12 +0100
Message-ID:
<1rhw0l701g4lu$.dlg@kimmeringer.de>
David wrote:

Eric, I have to use "instanceof" because is not the same to copy a
file from a shared folder (using CopyType class with java.io classes)
than from a remote ftp site (using FtpTransfer with FTPClient, for
example).


If you implement it the way you did, no. If you think object-
oriented you could. What is common to all copying? That data
has to go from A to B. So you have a DataSource and a DataSink.
Both can be represented as InputStream and OutputStream.

So instead of get and put as methods, define
public abstract InputStream getDataSource();
public abstract OutputStream getDataSink();

and implement one copy-method:

public abstract class CopyClass{
  public void copy(CopyClass source, CopyClass sink){
    InputStream is = source.getInputStream();
    OutputStream os = source.getOutputStream();

    byte[] buf = new byte[4096];
    int read;
    while ((read = is.read(buf)) != -1){
      os.write(buf, 0, read);
    }
  }
}

I think it's a bit complicate.


You think complicated ;-)

Regards, Lothar
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Lothar Kimmeringer E-Mail: spamfang@kimmeringer.de
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