330 Java Tips.pdf - FTP Server

General Java Questions I
--
Eric
Q: can anyone provide an example on how to use clone() and clonable interface?
Answer:
//Class Point uses default clone implementation that returns
//shallow copy of Point (which is sufficient in this case).
class Point implements Cloneable {
int x, y;
}
class ImmutableRectangle {
private Point lowerLeft = new Point();
private Point upperRight = new Point();
public Point getLowerLeftPoint() {
try {
return lowerLeft.clone();
}
catch(CloneNotSupportedException e) {
//shouldn't occur since Point is cloneable
throw new InternalError();
}
}
}
we don't want Rectangle points to be changed outside its class. the best
way would be to create a copy of Point object and pass it.
i5mast
MVP for Java 2
http://www.brainbench.com
Q: I am looking for more efficient compression APIs esp. for *.doc and *.html files.
I need some Java APIs wherein I can implement various compression algorithms. I
have already the GZIP compression technique shipped with JDK's java.util.zip
package. I am looking for more efficient compression APIs esp. for *.doc and *.html
files.
Answer: You often get better compression results for a large number of smaller files
by concatenating the uncompressed files and then compressing the result. That's
why tar.gz is often superior to zip for large numbers of html files (like API docs).
You will not get much better general-purpose compression than Zip, at least not until
you have a specific class of data and know very much about its structure. Even then
you'll need some experience and time working on a better compression method.
You might want to take a look at this Java implementation of bzip2:
http://www.aftexsw.com/aftex/products/java/bzip/
It uses more CPU cycles and memory but typically compresses better
than zip.
--
Marco
Q: I need to programmatically replace an entry in a zip file.
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