Java

[Dungeon-Dave]

I think most of the problems with Java are the number of bloated over-engineered frameworks that sprung up everywhere and half the world believing they needed full on J2EE for everything.

.. and the number of people that are used to procedural and don't grasp OO concepts in general, or those use to lack of standards and find Java restrictive because it imposes a certain framework, etc... Or we could generalise this with "the problem is definitely in the Java anguage, and not in the way we use it badly"....

But of course my bosses are of the opinion that you can use the same old approach no matter the tool. I can hardly wait to start screwing in some nails...

"if the only tool you have is a hammer, then every problem begins to look like a nail" is an antipattern I quote regularly. Same as the number of people using Excel for everything because that's what they're most familiar with, bending a spreadsheet tool to perform functions required of databases, calendars, etc.

I suppose the flipside is reinventing the wheel each time and completely ignoring code re-use. But right tool for the job, right time and a place, and everything.

[princec]

Java works for me It's just a massive pisser there isn't a Playstation or XBox port.

Cas

[zip accident]

But of course my bosses are of the opinion that you can use the same old approach no matter the tool. I can hardly wait to start screwing in some nails...

"if the only tool you have is a hammer, then every problem begins to look like a nail" is an antipattern I quote regularly.

However, you actually can hammer in screws; oval nails with a screwdriver? not a chance (unless the screwdriver is heavy enough to be used as a very poor hammer).

[GoatFoam]

I think this is the point where someone usually comes in, points out that all languages are theoretically equivalent and utterly misses the point.

[gilesgoat]

I think this is the point where someone usually comes in, points out that all languages are theoretically equivalent and utterly misses the point.

Yeah ..

[the2bears]

Right tool for the job, etc. I'd never be able to go back to a language without dynamic class loading.

Bill

[RamaBot]

Right tool for the job, etc. I'd never be able to go back to a language without dynamic class loading.

Why not?

[Dungeon-Dave]

I'm curious about that too - what is meant by "dynamic class loading"..? What languages support it?

(I know about dynamic module loading - not having to recompile Apache for adding in modules, etc. That the same thing?)

[t0ne]

Java allows you to load classes at runtime. For example JDBC uses this sort of thing with database drivers which allows you to specify the appropriate database driver class at runtime, perhaps from a config file without recompiling.
By default as long as the class is in the class path somewhere, Java can resolve a name to a class and load it for you. In fact you can write your own class loaders to pull in classes from anywhere you want (over a network connection, or from encrypted storage for example).

[sdetoni]

Java allows you to load classes at runtime. For example JDBC uses this sort of thing with database drivers which allows you to specify the appropriate database driver class at runtime, perhaps from a config file without recompiling.
By default as long as the class is in the class path somewhere, Java can resolve a name to a class and load it for you. In fact you can write your own class loaders to pull in classes from anywhere you want (over a network connection, or from encrypted storage for example).

Thats sound like a cool feature .... pity I've not found a use for it in Java. I'm of the opinion, if you try to be too clever when you don't have to be, then don't, you only end up confusing people, including yourself (give it 6 months). Actually, these dynamic classes sound a bit like function pointers in C, I've only every found one really good use for functions pointers, it had something to do with loading and calling dynamic functions/libraries I implemented in my play language that wrote called Moria.

[gilesgoat]

Java allows you to load classes at runtime. For example JDBC uses this sort of thing with database drivers which allows you to specify the appropriate database driver class at runtime, perhaps from a config file without recompiling.
By default as long as the class is in the class path somewhere, Java can resolve a name to a class and load it for you. In fact you can write your own class loaders to pull in classes from anywhere you want (over a network connection, or from encrypted storage for example).

That sounds a feature working only with interpreted languages ..

So you are kinda telling that "you can call function X / use class Y in your code withouth the need to link with lib Xyz and
the program 'automagically' will load and link the lib for you as you run it ?".

Well no, on a second tought you could implement it in various ways .. "a bit more evolved than a DLL" I'd say yet
fundamentally "same kind of idea" .. I can see pros and cons in this .. one 'pro' could be "I can update/change the class
under your arse without you needing to know about it".

I am not sure but I think you could do some kind of mechanism of that kind in C++ .. it would be nice if you could do
"all the loading / link you need" at startup all in once and then "once is all there, run full speed" otherwise I can see
potential for serious performance issues.

[t0ne]

Yes, the dynamic class loading is a lot like function pointers. In Java you'd define an interface and code to that. Apart from keeping the coupling loose, it also gives you the ability to dynamically change the implementation at runtime.

I should just clarify that you have to call a method passing the name of the class you want to load to do this in Java, it doesn't automagically do it if you try and use a particular class.

[Dungeon-Dave]

That sounds a feature working only with interpreted languages ..

I don't see how.

If I apply a service pack that updates DLLs on a machine, applications dependent upon those libraries don't need to be recompiled.

(and the fact it works with Java suggests that it definitely works with compiled languages, rather than interpreted... although I predict the thread digressing into the definition of how the JVM deals with bytecode any min now....)

[Orava]

Java allows you to load classes at runtime. For example JDBC uses this sort of thing with database drivers which allows you to specify the appropriate database driver class at runtime, perhaps from a config file without recompiling.
By default as long as the class is in the class path somewhere, Java can resolve a name to a class and load it for you. In fact you can write your own class loaders to pull in classes from anywhere you want (over a network connection, or from encrypted storage for example).

That sounds a feature working only with interpreted languages ..

So you are kinda telling that "you can call function X / use class Y in your code withouth the need to link with lib Xyz and
the program 'automagically' will load and link the lib for you as you run it ?".

Java jar-files work much like DLLs, except you don't have to do any linking or registering them.

For example, MySQL driver lives in a file my-sql-connector-java-5-6-1-bin.jar, you make sure that is on your application's classpath so its gets loaded when needed.

You can then dynamically access all the classes in that jar file, e.g.

Code: Select all

Class.forName("com.mysql.jdbc.Driver").newInstance();

or you can do this with any class as long as you know the name

e.g.

Code: Select all

Class megaLlamaClass = Class.forName("org.llamasoft.MegaLlama");
MegaLlama ml = (MegaLlama)megaLlamaClass.newInstance();
ml.spit();
ml.say("Bullseye!");

[Dungeon-Dave]

Is it possible under Java (although I'm thinking of ways to do it already) to parametrise this stuff in a separate file of constants then read that file in at run-time?

I'm not thinking of opening the file and reading it like a data source, more like the php_ini() function.

Also: what would be the format of that file - can it appear like an .ini file, or could I use XML to define finals which will be used later?