Question

我正在尝试从android示例编辑手势构建器代码。有一天我发现了这个noClassDefFound异常。

错误日志

04-04 02:13:51.278: E/AndroidRuntime(1002): FATAL EXCEPTION: main
04-04 02:13:51.278: E/AndroidRuntime(1002): java.lang.NoClassDefFoundError:     android.os.AsyncTask
04-04 02:13:51.278: E/AndroidRuntime(1002):     at  com.likith.gesturebuilder.GestureBuilderActivity.loadGestures(GestureBuilderActivity.java:250)
04-04 02:13:51.278: E/AndroidRuntime(1002):     at com.likith.gesturebuilder.GestureBuilderActivity.onCreate(GestureBuilderActivity.java:168)
04-04 02:13:51.278: E/AndroidRuntime(1002):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
04-04 02:13:51.278: E/AndroidRuntime(1002):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
04-04 02:13:51.278: E/AndroidRuntime(1002):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
04-04 02:13:51.278: E/AndroidRuntime(1002):     at android.app.ActivityThread.access$1500(ActivityThread.java:117)
04-04 02:13:51.278: E/AndroidRuntime(1002):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
04-04 02:13:51.278: E/AndroidRuntime(1002):     at android.os.Handler.dispatchMessage(Handler.java:99)
04-04 02:13:51.278: E/AndroidRuntime(1002):     at android.os.Looper.loop(Looper.java:123)
04-04 02:13:51.278: E/AndroidRuntime(1002):     at android.app.ActivityThread.main(ActivityThread.java:3683)
04-04 02:13:51.278: E/AndroidRuntime(1002):     at java.lang.reflect.Method.invokeNative(Native Method)
04-04 02:13:51.278: E/AndroidRuntime(1002):     at java.lang.reflect.Method.invoke(Method.java:507)
04-04 02:13:51.278: E/AndroidRuntime(1002):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
04-04 02:13:51.278: E/AndroidRuntime(1002):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
04-04 02:13:51.278: E/AndroidRuntime(1002):     at dalvik.system.NativeStart.main(Native Method)

代码

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) 
{
    super.onActivityResult(requestCode, resultCode, data);

    if (resultCode == RESULT_OK) 
    {
        switch (requestCode) 
        {
            case REQUEST_NEW_GESTURE:
                loadGestures();
                break;
        }
    }
}

private void loadGestures()
{
    if (mTask != null && mTask.getStatus() != GesturesLoadTask.Status.FINISHED)
    {
        mTask.cancel(true);
    }  

    mTask = (GesturesLoadTask) new GesturesLoadTask().execute();
}


public class GesturesLoadTask extends AsyncTask<Void, NamedGesture, Integer> 
{
    private int mThumbnailSize;
    private int mThumbnailInset;
    private int mPathColor;

    @Override
    protected void onPreExecute() 
    {
        super.onPreExecute();

        final SharedPreferences pref= PreferenceManager.getDefaultSharedPreferences(getBaseContext());
        final Resources resources = getResources();
        //mPathColor = resources.getColor(R.color.gesture_color);
        mPathColor = pref.getInt("gesture_color", Color.parseColor("#ffe3a0"));
        mThumbnailInset = (int) resources.getDimension(R.dimen.gesture_thumbnail_inset);
        mThumbnailSize = (int) resources.getDimension(R.dimen.gesture_thumbnail_size);

        findViewById(R.id.addButton).setEnabled(false);    

        mAdapter.setNotifyOnChange(false);            
        mAdapter.clear();
    }

    @Override
    protected Integer doInBackground(Void... params) 
    {
        if (isCancelled()) return STATUS_CANCELLED;
        if (!Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())) 
        {
            return STATUS_NO_STORAGE;
        }

        final GestureLibrary store = sStore;

        if (store.load()) 
        {
            for (String name : store.getGestureEntries()) 
            {
                if (isCancelled()) break;

                for (Gesture gesture : store.getGestures(name)) 
                {
                    final Bitmap bitmap = gesture.toBitmap(mThumbnailSize, mThumbnailSize,mThumbnailInset, mPathColor);
                    final NamedGesture namedGesture = new NamedGesture();
                    namedGesture.gesture = gesture;
                    namedGesture.name = name;

                    mAdapter.addBitmap(namedGesture.gesture.getID(), bitmap);
                    publishProgress(namedGesture);
                }
            }
            return STATUS_SUCCESS;
        }
        return STATUS_NOT_LOADED;
    }

    @Override
    protected void onProgressUpdate(NamedGesture... values) 
    {
        super.onProgressUpdate(values);

        final GesturesAdapter adapter = mAdapter;
        adapter.setNotifyOnChange(false);

        for (NamedGesture gesture : values) 
        {
            adapter.add(gesture);

            tap_info.setVisibility(View.VISIBLE);
        }

        adapter.sort(mSorter);
        adapter.notifyDataSetChanged();
    }

    @Override
    protected void onPostExecute(Integer result) 
    {
        super.onPostExecute(result);

        if (result == STATUS_NO_STORAGE) 
        {
            getListView().setVisibility(View.GONE);
            mEmpty.setVisibility(View.VISIBLE);
            mEmpty.setText(getString(R.string.gestures_error_loading,mStoreFile.getAbsolutePath()));
        } 
        else 
        {
            findViewById(R.id.addButton).setEnabled(true); 
            checkForEmpty();
        }
    }
}

noClassDefFound异常是什么意思以及如何解决它。请帮忙。

Answer 1

NoClassException意味着在类路径中的任何位置都找不到类，在本例中为AsyncTask。

查看此主题的一些解决方案： Android: NoClassDefFoundError android.os.AsyncTask

其中一个使用Class.forName（String）调用手动加载类。

noClassDefFound android

1 个答案: