Create new ClassLoader to reload Class

Question

I want to create a new ClassLoader everytime my method is called.

So I can reload a class without exiting my program.

A way how I can update a class loaded by ClassLoader would also be a solution.

How can I achieve that?

Answer 1

I found a good explained answer here:

http://www.exampledepot.com/egs/java.lang/reloadclass.html

The important thing is to have two binary folders, in my case: one for the testcases and one for the program source.

Quote:

URL[] urls = null;
try {
    // Convert the file object to a URL
    File dir = new File(System.getProperty("user.dir")
        +File.separator+"dir"+File.separator);
    URL url = dir.toURL();        // file:/c:/almanac1.4/examples/
    urls = new URL[]{url};
} catch (MalformedURLException e) {
}

try {
    // Create a new class loader with the directory
    ClassLoader cl = new URLClassLoader(urls);

    // Load in the class
    Class cls = cl.loadClass("MyReloadableClassImpl");