Java ClassNotFound exception - why doesn't this work?

Hi Everyone!

I've been beating my head against this all day. I've been trying to wrap the UnityPlayerActivity class so that I can get orientation from Android devices into my project. I understand how the code *should* work, but no matter what I do the application refuses to see the wrapper class at runtime. Here's the nuts-and-bolts of what I'm trying to get to work...

Code (csharp):

1.  
2.  
3. JAVA SOURCE CODE STORED IN Assets/Plugins/Android/src/Gyro.java
4. ---------------------------------------------------------------
5.  
6.  
7. package com.tap.rfyl;
8.  
9. import com.unity3d.player.UnityPlayerActivity;
10. import android.content.Context;
11. import android.hardware.Sensor;
12. import android.hardware.SensorEvent;
13. import android.hardware.SensorEventListener;
14. import android.hardware.SensorManager;
15. import android.os.Bundle;
16. import android.util.Log;
17. import android.app.Activity;
18.  
19. public class Gyro extends UnityPlayerActivity
20. {
21.     private static final String TAG = "Gyro_Unity";
22.     private SensorManager mSensorManager;
23.     private Sensor accelerometer;
24.     private Sensor magnetometer;
25.  
26.     static public float xmag;
27.     static public float ymag;
28.     static public float zmag;
29.  
30.     private final SensorEventListener mListener = new SensorEventListener()
31.     {   float[] mGravity;
32.         float[] mGeomagnetic;
33.  
34.         public void onAccuracyChanged(Sensor sensor, int accuracy)
35.         {   // Not used
36.         }
37.        
38.         public void onSensorChanged(SensorEvent event)
39.         {   if (event.sensor.getType() == Sensor.TYPE_ACCELEROMETER)
40.             {   mGravity = event.values;
41.             }
42.             if (event.sensor.getType() == Sensor.TYPE_MAGNETIC_FIELD)
43.             {   mGeomagnetic = event.values;
44.             }
45.             if (mGravity != null  mGeomagnetic != null)
46.             {   float R[] = new float[9];
47.                 float I[] = new float[9];
48.                 boolean success = SensorManager.getRotationMatrix(R, I, mGravity, mGeomagnetic);
49.                 if (success)
50.                 {   float orientation[] = new float[3];
51.                     SensorManager.getOrientation(R, orientation);
52.                     xmag = orientation[0];  // azimuth
53.                     ymag = orientation[1];  // pitch
54.                     zmag = orientation[2];  // roll
55.                 }
56.             }
57.         }
58.     };
59.  
60.     @Override
61.     protected void onCreate(Bundle savedInstanceState)
62.     {   mSensorManager = (SensorManager)getSystemService(Context.SENSOR_SERVICE);
63.         accelerometer  = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
64.         magnetometer   = mSensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD);
65.         super.onCreate(savedInstanceState);
66.     }
67.  
68.     @Override
69.     protected void onResume()
70.     {   mSensorManager.registerListener(mListener, accelerometer, SensorManager.SENSOR_DELAY_GAME);
71.         mSensorManager.registerListener(mListener, magnetometer,  SensorManager.SENSOR_DELAY_GAME);
72.         super.onResume();
73.     }
74.  
75.     @Override
76.     protected void onStop()
77.     {   mSensorManager.unregisterListener(mListener);
78.         super.onStop();
79.     }
80.  
81.     @Override
82.     protected void onPause()
83.     {   mSensorManager.unregisterListener(mListener);
84.         super.onPause();
85.     }
86.    
87.     public static float getX()
88.     {   return xmag;
89.     }
90.  
91.     public static float getY()
92.     {   return ymag;
93.     }
94.  
95.     public static float getZ()
96.     {   return zmag;
97.     }
98. }
99.  
100.  
101.  
102. COMMAND-LINE COMPILE OF JAVASCRIPT
103. ----------------------------------
104.  
105.  
106.  
107. set PATH=%PATH%;C:\Program Files (x86)\Java\jdk1.7.0_40\bin
108.  
109. javac Gyro.java -classpath "C:\Program Files (x86)\Unity\Editor\Data\PlaybackEngines\androiddevelopmentplayer\bin\classes.jar" -bootclasspath "G:\adt-bundle-windows-x86-20130917\sdk\platforms\android-16\android.jar" -d . -verbose
110.  
111. javap -s -verbose com.tap.rfyl.Gyro
112.  
113. jar cvfM ../Gyro.jar com/
114.  
115.  
116.  
117. MANIFEST FILE STORED IN Assets/Plugins/Android/AndroidManifest.xml
118. ------------------------------------------------------------------
119.  
120.  
121.  
122. <?xml version="1.0" encoding="utf-8"?>
123. <manifest xmlns:android="http://schemas.android.com/apk/res/android"
124.           package="com.tap.rfyl"
125.           android:versionCode="1"
126.           android:versionName="1.0">         
127.     <uses-sdk android:minSdkVersion="16" android:targetSdkVersion="16" />
128.     <application android:icon="@drawable/app_icon"
129.                  android:label="@string/app_name">
130.         <activity android:name=".Gyro"
131.                   android:screenOrientation="landscape"
132.                   android:configChanges="fontScale|keyboard|keyboardHidden|locale|mnc|mcc|navigation|orientation|screenLayout|screenSize|smallestScreenSize|uiMode|touchscreen"
133.                   android:label="@string/app_name">
134.             <intent-filter>
135.                 <action   android:name="android.intent.action.MAIN" />
136.                 <category android:name="android.intent.category.LAUNCHER" />
137.             </intent-filter>
138.         </activity>
139.     </application>
140. </manifest>
141.  
142.  
143.  

I've tried every conceivable permutation suggested by various sources. I've absolutely tried using a fully qualified path in the "Activity" tag. Nothing has changed the outcome - when I try and run the app on my Android device (a Galaxy Tab 3) it fails immediately with a "ClassNotFound" exception for "Gyro".

I tried to build a stripped version of the code that only implemented "onCreate" and did nothing else. Got the same error.

I tried building the .jar file against "androidplayer" and "androiddevelopmentplayer", and nothing changed.

Basically, I know I must be missing something really obvious, but I can't see it.

Any help would be greatly appreciated!

Nick