Java Programming Code Examples

Java > Networking Code Examples

Multi ClassLoader Demo



Multi ClassLoader Demo

import java.net.URLClassLoader;
import java.net.URL;
import java.io.File;

public class MultiCLDemo
    {
     public static void main(String[] args)
         {
         if (args.length<3)
             {
             System.out.println("Usage: java MultiCLDemo "+" ...");
             System.out.println("Loads and runs toString() on class_name "+"found in each subDir.");
             System.exit(0);
         }
         try
             {
             String className = args[0];
             int count = args.length-1;
             URL tmpURL;
             Object[] objects = new Object[count];
             URLClassLoader[] loaders = new URLClassLoader[count];
             System.out.println("Loading "+count+" different classes "+"named: "+className);
             for (int i=0; i                 {
                 tmpURL = new File(args[i+1]).toURL();
                 System.out.println("\nLoading from: "+tmpURL);
                 loaders[i] = new URLClassLoader(new URL[] { tmpURL });
                 objects[i] = loaders[i].loadClass(className).newInstance();
                 for (int k=0; k<=i; k++)
                     {
                     System.out.println("Got object: "+objects[k]);
                 }
             }
         }
         catch (Exception e)
             {
             e.printStackTrace();
         }
     }
}


/*Some sample classes to load...

// c:\a/HelloWorld.java
public class HelloWorld
    {
     public String toString()
         {
         return "Hello";
     }
}

// c:\b/HelloWorld.java
public class HelloWorld
    {
     public String toString()
         {
         return "World";
     }
}

// c:\c/HelloWorld.java
public class HelloWorld
    {
     public String toString()
         {
         return "Hello World";
     }
}

The code running...

java MultiCLDemo HelloWorld a b c

Loading 3 different classes named:
HelloWorldLoading from: file:/.../class_loader_demo/a/Got object:
HelloLoading from: file:/.../class_loader_demo/b/Got object:
HelloGot object: WorldLoading from: file:/.../class_loader_demo/c/Got object:
HelloGot object: WorldGot object: Hello World

regards, btcoburn*/