[java]dynamic class loading

[CountNoobula]

Ok, I have been looking online now, but I can't seem to find a tutorial for exactly what I want to do... Could someone please assist?

Essentially I want to create a program that will load all classes inside a jar and invoke a function (load()) in each of them. It will not have a hard set list but will dynamically load all classes on runtime.

[AaRoNg11]

It's a while since i've done anything with Java, but you might want to take a look [url=http://download.oracle.com/javase/1.4.2/docs/api/java/lang/reflect/package-summary.html]here[/url]

[CountNoobula]

that looks very close to what i am looking for, i will look into manipulation of it... thanks

[robmaister12]

as long as they don't have constructors it's as easy as Class.forName( ... ).newInstance();

and it'll work best if you have all your classes inheriting from an abstract class or if they all implement and interface.

[CountNoobula]

thanks :)

[bobthe2lol]

If you're interested, here is the chat command dynamic loader for my custom minecraft server.

static Map<String,ArrayList<Command>> commands = new HashMap<String,ArrayList<Command>>();
public static void RegisterPlugins() throws InstantiationException, IllegalAccessException, ClassNotFoundException{
        ClassLoader cloader = ClassLoader.getSystemClassLoader();
        File directory = new File("./src/Server/Events/ChatCommands");
        for(File f:directory.listFiles()){
            if(f.isFile()&&!f.getName().contains("ommand.")&&!f.getName().contains("andler.")&&f.getName().startsWith("plugin_")){
                System.out.println(f.getName());
                Class ccl = cloader.loadClass("Server.Events.ChatCommands."+f.getName().replace(".java", ""));
                Command cmd = (Command) ccl.newInstance();
                ArrayList<Command> blah = new ArrayList<Command>();
                if(!commands.containsKey(cmd.GetCmd())){
                    Utils.Logger.Log("Command not contained. Adding.");
                    blah.add(cmd);
                    commands.put(cmd.GetCmd(), blah);
                } else{
                    Utils.Logger.Log("Command contained. Adding.");
                    blah = (ArrayList<Command>) commands.get(cmd.GetCmd()).clone();
                    blah.add(cmd);
                    commands.put(cmd.GetCmd(), blah);
                }
            }
        }
    }

It's a multimap because I want more than 1 command to be able to register the same chat command. Like /jump, and /jump 40 for specified and nonspecified height.

[CountNoobula]

ah, that could help quite nicely, thanks!

[bord2tears]

Reflection is the technology you want to use, if you didn't know.
[url]http://download.oracle.com/javase/tutorial/reflect/class/index.html[/url]
ClassLoader is the specific thing used in that example.

[VoiDeD]

[QUOTE=bobthe2lol;28308738]If you're interested, here is the chat command dynamic loader for my custom minecraft server.

static Map<String,ArrayList<Command>> commands = new HashMap<String,ArrayList<Command>>();
public static void RegisterPlugins() throws InstantiationException, IllegalAccessException, ClassNotFoundException{
        ClassLoader cloader = ClassLoader.getSystemClassLoader();
        File directory = new File("./src/Server/Events/ChatCommands");
        for(File f:directory.listFiles()){
            if(f.isFile()&&!f.getName().contains("ommand.")&&!f.getName().contains("andler.")&&f.getName().startsWith("plugin_")){
                System.out.println(f.getName());
                Class ccl = cloader.loadClass("Server.Events.ChatCommands."+f.getName().replace(".java", ""));
                Command cmd = (Command) ccl.newInstance();
                ArrayList<Command> blah = new ArrayList<Command>();
                if(!commands.containsKey(cmd.GetCmd())){
                    Utils.Logger.Log("Command not contained. Adding.");
                    blah.add(cmd);
                    commands.put(cmd.GetCmd(), blah);
                } else{
                    Utils.Logger.Log("Command contained. Adding.");
                    blah = (ArrayList<Command>) commands.get(cmd.GetCmd()).clone();
                    blah.add(cmd);
                    commands.put(cmd.GetCmd(), blah);
                }
            }
        }
    }

It's a multimap because I want more than 1 command to be able to register the same chat command. Like /jump, and /jump 40 for specified and nonspecified height.[/QUOTE]

I don't mean to be touchy, but: dear god that code. :gonk:

How do you even maintain something like that.