java.lang.NoSuchMethodException where getDeclaredMethods() shows otherwise

My problem is simple. So simple I can't seem to figure it out. I am passing a qualified class name to a BroadcastReceiver as a String in an Intent.

The goal is to instantiate an object from the class name using reflection, and call a method which we know exists, because it implements a proprietary interface. I am even checking it against getDeclaredMethods() which says its there, but when I try to invoke that method, it throws a java.lang.NoSuchMethodException.

String myClass = intent.getStringExtra("name");        
Class<?> c = Class.forName(myClass);
Object object = c.newInstance();

// Get the files from the interface

Method ms[] = c.getDeclaredMethods();
for (Method m1 : ms) {
    Log.i("METHOD", "METHODS " + m1.getName());
}

Method m = c.getDeclaredMethod("getStrings", (Class<?>) null);
String[] someStrings = (String[]) m.invoke(object, (Object[]) null);

m = c.getDeclaredMethod("getThings", (Class<?>) null);
Thing[] things = (Thing[]) m.invoke(object, (Object[]) null);

Here is the LogCat output:

08-30 23:37:36.150: INFO/METHOD(2336): METHODS getStrings
08-30 23:37:36.150: INFO/METHOD(2336): METHODS getThings
08-30 23:37:36.150: WARN/System.err(2336): java.lang.NoSuchMethodException: getStrings
08-30 23:37:36.150: WARN/System.err(2336):     at java.lang.ClassCache.findMethodByName(ClassCache.java:247)
08-30 23:37:36.150: WARN/System.err(2336):     at java.lang.Class.getDeclaredMethod(Class.java:731)
08-30 23:37:36.15开发者_开发问答0: WARN/System.err(2336):     at com.app.MyBroadcastReceiver.onReceive(MyBroadcastReceiver.java:45)
08-30 23:37:36.150: WARN/System.err(2336):     at android.app.ActivityThread.handleReceiver(ActivityThread.java:1794)
08-30 23:37:36.150: WARN/System.err(2336):     at android.app.ActivityThread.access$2400(ActivityThread.java:117)
08-30 23:37:36.150: WARN/System.err(2336):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:981)
08-30 23:37:36.150: WARN/System.err(2336):     at android.os.Handler.dispatchMessage(Handler.java:99)
08-30 23:37:36.160: WARN/System.err(2336):     at android.os.Looper.loop(Looper.java:130)
08-30 23:37:36.160: WARN/System.err(2336):     at android.app.ActivityThread.main(ActivityThread.java:3683)
08-30 23:37:36.160: WARN/System.err(2336):     at java.lang.reflect.Method.invokeNative(Native Method)
08-30 23:37:36.160: WARN/System.err(2336):     at java.lang.reflect.Method.invoke(Method.java:507)
08-30 23:37:36.160: WARN/System.err(2336):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
08-30 23:37:36.160: WARN/System.err(2336):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
08-30 23:37:36.160: WARN/System.err(2336):     at dalvik.system.NativeStart.main(Native Method)

Is there something I am missing here?

Edit: Added the code to the class

public class MyClass implements MyInterface {

    @Override
    public String[] getStrings() {
        // Stub
        return new String[2];
    }

    @Override
    public Thing[] getThings() {
        // Stub
        return new Thing[2];
    }

}

Note: The BroadcastReceiver and the Class are in different projects.

getDeclaredMethod requires you give the right parameters. If there are no parameters, then instead of passing "null", you need to pass absolutely nothing.

For example, here is a code snippet for hashCode, which takes no arguments

Method m = c.getDeclaredMethod("hashCode");
System.out.println("test");
Method m2 = c.getDeclaredMethod("hashCode", (Class<?>) null);

it will print out "test", then throw a MethodNotFound exception as hashCode takes no arguments. If you want to get the argument types as well as the name, execute the getParameterTypes on the method object

for (Method m1 : ms) {
    System.out.println( "METHODS " + m1.getName());
    for (Class paramC : m1.getParameterTypes()) {
        System.out.println(paramC.getName());
    }
    }

This might help. http://code.google.com/p/android/issues/detail?id=2812

Post a comment or edit your original post if its not the same, with more specifics. :)

The thread I linked above is about a bug with the platform causing others similar issues.

Few possible reasons:

• Are you passing the right parameters in trying to get the declared method?
• If the method doesn't take any parameter, try passing new Class[0] instead of null

Make sure you're sending the correct parameters list in the getDeclaredMethod call. Right now you're sending (Class<?>) null. What is the signature of the method getStrings?

there could be a couple of reasons for this, firstly, your src object may not be the one you thought it to be. Secondly, you might be trying to access a private member. Giving the code of this class u r instantiating would be great!