Re: java.lang.ClassLoader

[Kresten Krab Thorup <krab at eos dot dk>]

> Veena Murthy wrote:
> 
> Hi,
> 
> Can anyone point me to code examples for using java.lang.ClassLoader.
> 

The usual scenario is to simply create an instance of URLClassLoader,
passing in an array or URL's that is the class path.  Here's a blurp
illustrating how to start a new "application" from inside Java.  To use
it, create an AppRunner and pass it to a fresh Thread.

import java.lang.reflect.Method;
import java.lang.reflect.InvocationTargetException;
import java.net.URL;

public class AppRunner implements Runnable
{
  String mainClass = null;
  String[] mainArgs = null;
  URL[] classPath = null;
  
  public AppRunner (String mainClass, String[] mainArgs, URL[]
classpath)
  {
    this.mainClass = mainClass;
    this.mainArgs  = mainArgs;
    this.classPath = classpath;
  }

  public void run ()
  {
    try {
      ClassLoader loader = java.net.URLClassLoader(classPath);
      Class klass = loader.loadClass (mainClass);
      
      Class[] atype = new Class[1];
      atype[0] = (new String[0]).getClass();
      
      Method mainMethod = klass.getDeclaredMethod ("main", atype);
      
      Object[] a = new Object[1];
      a[0] = mainArgs;
      
      mainMethod.invoke (null, a);

    } catch (Throwable ex) {
      ex.printStackTrace ();

    }
  }
}

-- 
Kresten Krab Thorup, Partner
Eastfork Object Space (EOS), Margrethepladsen 3, 8000  Århus C, Denmark
Tel: +45 8732 8787 / Fax: +45 8732 8788 / Mob: +45 2343 4626