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Defining classes runtime

Yohan Liyanage

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posted 18 years ago

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Hi everybody!

I would like to know if there is a possibility to create new classes and make use of them during the runtime of an application. I have heard about Java Reflection API, can it be used to solve my problem ?

Yohan Liyanage
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Yohan Liyanage

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posted 18 years ago

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anybody?

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Rahul Bhattacharjee

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posted 18 years ago

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Java reflection api is used for creating objects at rumtime , but the classes should be already available.It cannot create classes at runtime.It can load class , instantiate object and other related stuffs.

Rahul Bhattacharjee
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Jesper de Jong

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posted 18 years ago

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Why would you want to create a new class at runtime - why do you think that would be a useful feature?

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Harish Tiruvile

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posted 18 years ago

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Are you asking for auto generated files??

somewhere i read java file can created , compiled and executed at runtime using scripting languages

Giving up is the easiest thing in the world to do..but holding it together when everything seems like falling apart is true strength!!
with regards, Harish.T

William Brogden

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posted 18 years ago

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Yes, reflection gives you the methods for dynamically loading classes at runtime, and yes you can compile a class from within an application, so the parts are all there. It is not exactly simple.

You might find it a lot easier to use one of the scripting languages that can dynamically create scripts and be executed in the JVM. See Groovy, JPython, JRuby and probably a bunch more.

Bill

Yohan Liyanage

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posted 18 years ago

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Thanks everybody. I'll look into those scripting languages. I wanted to know if there is a possibility to dynamically extend a Java program.
[ August 27, 2007: Message edited by: Yohan Liyanage ]

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Ulf Dittmer

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posted 18 years ago

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I've found the Javassist library very useful for this. Since it creates real Java classes, I'd think it would be much faster that anything that involves a scripting language (assuming that those are essentially interpreted, not compiled to bytecode).

Harish Tiruvile

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I wanted to know if there is a possibility to dynamically extend a Java program

yes, you can dynamically extend java classes

Giving up is the easiest thing in the world to do..but holding it together when everything seems like falling apart is true strength!!
with regards, Harish.T

Rahul Bhattacharjee

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posted 18 years ago

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Originally posted by harish thrivile:

yes, you can dynamically extend java classes

how ? and useful link for this.

Rahul Bhattacharjee
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Yohan Liyanage

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posted 18 years ago

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I came across this article when I was searching the web for this problem.

Add dynamic Java code to your application By Li Yang :
http://www.javaworld.com/javaworld/jw-06-2006/jw-0612-dynamic.html

Yohan Liyanage
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Ulf Dittmer

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posted 18 years ago

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Originally posted by Rahul Bhattacharjee:
how ? and useful link for this.

As was said before, Javassist can do this. It comes with a tutorial that demonstrates how to do that.

Rahul Bhattacharjee

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posted 18 years ago

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Originally posted by Ulf Dittmer:

As was said before, Javassist can do this. It comes with a tutorial that demonstrates how to do that.

Thanks , I will lookinto it.Wasn't aware of this.

Rahul Bhattacharjee
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