'TAG' has private access in 'android.support.v4.app.FragmentActivity'

问题

Almost everything in my activity is working fine, except for wherever TAG is referenced. TAG gets a red line and says: 'TAG' has private access in 'android.support.v4.app.FragmentActivity'.

MainActivity (without imports)-

public class MainActivity extends AppCompatActivity {
    public static final String DATA_PATH = Environment
            .getExternalStorageDirectory().toString() + "/MainActivity";
    public static final String lang = "eng";

    protected Button _button;
    protected ImageView _image;
    protected TextView _field;
    protected String _path;
    protected boolean _taken;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        String[] paths = new String[] { DATA_PATH, DATA_PATH + "tessdata/" };

        for (String path : paths) {
            File dir = new File(path);
            if (!dir.exists()) {
                if (!dir.mkdirs()) {
                    Log.v(TAG, "ERROR: Creation of directory " + path + " on sdcard failed");
                    return;
                } else {
                    Log.v(TAG, "Created directory " + path + " on sdcard");
                }
            }

        }

        if (!(new File(DATA_PATH + "tessdata/" + lang + ".traineddata")).exists()) {
            try {

                AssetManager assetManager = getAssets();
                InputStream in = assetManager.open("tessdata/" + lang + ".traineddata");
                //GZIPInputStream gin = new GZIPInputStream(in);
                OutputStream out = new FileOutputStream(DATA_PATH
                        + "tessdata/" + lang + ".traineddata");

                // Transfer bytes from in to out
                byte[] buf = new byte[1024];
                int len;
                //while ((lenf = gin.read(buff)) > 0) {
                while ((len = in.read(buf)) > 0) {
                    out.write(buf, 0, len);
                }
                in.close();
                //gin.close();
                out.close();

                Log.v(TAG, "Copied " + lang + " traineddata");
            } catch (IOException e) {
                Log.e(TAG, "Was unable to copy " + lang + " traineddata " + e.toString());
            }
        }

        _image = ( ImageView ) findViewById( R.id.image );
        _field = ( TextView ) findViewById( R.id.field );
        _button = ( Button ) findViewById( R.id.button );
        _button.setOnClickListener( new ButtonClickHandler() );

        _path = Environment.getExternalStorageDirectory() + "/Login Data.jpg";
    }

    public class ButtonClickHandler implements View.OnClickListener
    {
        public void onClick( View view ){
            startCameraActivity();
        }
    }

    protected void startCameraActivity()
    {
        File file = new File( _path );
        Uri outputFileUri = Uri.fromFile( file );

        Intent intent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE );
        intent.putExtra( MediaStore.EXTRA_OUTPUT, outputFileUri );

        startActivityForResult( intent, 0 );
    }

    protected void onPhotoTaken()
    {
        _taken = true;

        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inSampleSize = 4;

        Bitmap bitmap = BitmapFactory.decodeFile( _path, options );
        _image.setImageBitmap(bitmap);

        _field.setVisibility( View.GONE );

        ExifInterface exif = new ExifInterface(_path);

        int exifOrientation = exif.getAttributeInt(
                ExifInterface.TAG_ORIENTATION,
                ExifInterface.ORIENTATION_NORMAL);

        int rotate = 0;

        switch (exifOrientation) {
            case ExifInterface.ORIENTATION_ROTATE_90:
                rotate = 90;
                break;
            case ExifInterface.ORIENTATION_ROTATE_180:
                rotate = 180;
                break;
            case ExifInterface.ORIENTATION_ROTATE_270:
                rotate = 270;
                break;
        }

        if (rotate != 0) {
            int w = bitmap.getWidth();
            int h = bitmap.getHeight();

            // Setting pre rotate
            Matrix mtx = new Matrix();
            mtx.preRotate(rotate);

            // Rotating Bitmap & convert to ARGB_8888, required by tess
            bitmap = Bitmap.createBitmap(bitmap, 0, 0, w, h, mtx, false);
        }
        bitmap = bitmap.copy(Bitmap.Config.ARGB_8888, true);

        TessBaseAPI baseApi = new TessBaseAPI();
        baseApi.init(DATA_PATH, lang);
        baseApi.setImage(bitmap);
        String recognizedText = baseApi.getUTF8Text();
        baseApi.end();
    }

    @Override
    protected void onSaveInstanceState( Bundle outState ) {
        outState.putBoolean( MainActivity.PHOTO_TAKEN, _taken );
    }

    @Override
    protected void onRestoreInstanceState( Bundle savedInstanceState)
    {
        Log.i( "MakeMachine", "onRestoreInstanceState()");
        if( savedInstanceState.getBoolean( MainActivity.PHOTO_TAKEN ) ) {
            onPhotoTaken();
        }
    }

回答1:

You should define a constant for your tag in MainActivity:

private static final String TAG = "MainActivity"

回答2:

try the following

private static final String TAG = MainActivity.class.getSimpleName();

You can use this field in your any Activity or Fragment.

回答3:

Well that's just an Android's way of telling us that we haven't defined TAG. To define the TAG in the current file, we can go to MainActivity Class and type "logt", you will get some auto code suggestions from Android studio, press enter there and you will get following code

private static final String TAG = "MainActivity";

Once you add this to your code, your error will be gone

回答4:

Practical note: following is the better approach

private static final String TAG = MainActivity.class.getSimpleName();

as compared to:

private static final String TAG = "MainActivity";

来源：https://stackoverflow.com/questions/37886301/tag-has-private-access-in-android-support-v4-app-fragmentactivity