I have a library that I plan on using in dex form. I want to compile directly against this library, but not export it. Instead I want to drop it in my resources and use a class loader to actually instantiate it.
So here's my library:
public class Foo {
public doFoo(String message) {
}
public doFoo(int count, String message) {
}
}
Now I want to call doFoo(). A lot. More than it's probably reasonable to use reflection for. Right now it works with:
public class FooConsumer {
private final DexClassLoader fooLoader;
public FooConsumer(DexClassLoader fooLoader) {
this.fooLoader = fooLoader;
}
public void go() {
Class<?> fooClass = fooLoader.loadClass("com.library.Foo");
Object fooInstance = fooClass.newInstance();
Method fooMethodDoFoo = fooClass.getMethod("doFoo", String.class);
fooMethodDoFoo.invoke(fooInstance, "Hello World");
}
This is obviously fugly. Especially since I haven't included any of the exception handling, as there are half a dozen throwables to catch in there. I could cache a bunch of stuff, helping me with speed a bit, but not a lot.
Normally I'd have both aware of a third library that has an interface, but the library has some static methods and I can't edit it anyway. It'd be really nice if I could do something like:
public class FooConsumer {
private FooAccessor accessor;
public FooConsumer(DexClassLoader fooLoader) {
Object fooInstance = fooLoader.loadClass("com.library.Foo").newInstance();
Log.i("TEST", "fooInstance: " + fooInstance);
this.accessor = new FooAccessor(fooInstance);
}
public void go() {
accessor.doFoo("Hello World");
}
private static class FooAccessor {
private Foo fooInstance;
public FooAccessor(Object instance) {
fooInstance = (Foo)instance;
}
public void doFoo(String message) {
fooInstance.doFoo(message);
}
}
}
See what I did there? The inner class is just a wrapper around the Foo object, I've linked against it, but not exported it, and all is good in the world. But it doesn't work. In logcat I get
I/TEST: fooInstance: com.library.Foo@413b1b68
E/AndroidRuntime: java.lang.NoClassDefFoundError: com.library.Foo
...
Is there a way to have FooAccessor use the class loader I passed in? Or is the use of class loaders a damnation into reflection hell.