330 Java Tips.pdf - FTP Server

General Java Questions I
http://www.pobox.com/~skeet
this advice first was published on comp.lang.java.programmer
Q: I find such function, but in Class class. Is it possible to use it (or something like
this) in another class? Exactly I would like call: super.super.method1();
Answer: No, you can only access methods of your direct ancestor.
The only way to do this is by using reflection:
import java.lang.reflect.*;
Class superduper = this.getClass().
getSuperClass().
getSuperClass();
Method ssMethod = superduper.getMethod("method1",null);
ssMethod.invoke(this,null);
(I didn't check the exact syntax and parameters of the above code.)
However the necessity to skip a hierarchy shows that there is something wrong with
the design of your application. You should fix this instead of using dirty tricks like the
above.
---
Carl Rosenberger
db4o - database for objects - http://www.db4o.com
Q: If anybody can provide some tips on how to design this smartly...
Q: I am facing a problem that might sound common to you all. I have to write a
switch statement with 40 case statement. I am wondering if there can be some way to
reduce this. If anybody can provide some tips on how to design this smartly. ;)
Answer: The alternatives are:
an array you index into to get values or delegates.
an array you binary search.
--
Roedy Green
Q: I want to use some java variables , across multiple java files. Is there some
thing like a "extern in C" in java ??
Answer: If you want to share constants, the usual way is to create a class like this:
public class My_Constants {
public static final int ID_OK = 1;
public static final int ID_CANCEL = 2;
}
public static final String MSG_OK = "Okay.";
public static final String MSG_ERROR = "An error occurred.";
If you want to share a single object instance across your application, use the
Singleton pattern.
Actually, the more common way is to create an interface, like this:
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