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我想将字符串从片段内的Editext传递给asynctask，我该怎么做？我在这里看过类似的帖子，但我做错了什么。Android将单个字符串从片段传递给Asynctask
片段
EditText txt=(EditText) view.findViewById(R.id.textSearch);
EditText date=(EditText) view.findViewById(R.id.textDate);
// Get Editext string and pass it to the Asynctask
txtSearch = txt.getEditableText().toString();
Log.d(TAG, "variabile text " + txtSearch);
new TessAsyncEngine().execute(txtSearch);
的AsyncTask（去//检测字）
public class TessAsyncEngine extends AsyncTask<Object, Void, String> {
static final String TAG = "DBG_" + TessAsyncEngine.class.getName();
private Bitmap bmp;
private Activity context;
@Override
protected String doInBackground(Object... params) {
try {
if(params.length < 2) {
Log.e(TAG, "Error passing parameter to execute - missing params");
return null;
}
if(!(params[0] instanceof Activity) || !(params[1] instanceof Bitmap)) {
Log.e(TAG, "Error passing parameter to execute(context, bitmap)");
//Log.e(TAG, "Error passing parameter " + params[0].toString() + params[1].toString());
return null;
}
context = (Activity)params[0];
bmp = (Bitmap)params[1];
if(context == null || bmp == null) {
Log.e(TAG, "Error passed null parameter to execute(context, bitmap)");
return null;
}
int rotate = 0;
if(params.length == 3 && params[2]!= null && params[2] instanceof Integer){
rotate = (Integer) params[2];
}
if(rotate >= -180 && rotate <= 180 && rotate != 0)
{
bmp = Tools.preRotateBitmap(bmp, rotate);
Log.d(TAG, "Rotated OCR bitmap " + rotate + " degrees");
}
TessEngine tessEngine = TessEngine.Generate(context);
bmp = bmp.copy(Bitmap.Config.ARGB_8888, true);
String result = tessEngine.detectText(bmp);
//detect words
String textSearch = new ScanFragment().txtSearch;
if (result.equalsIgnoreCase(textSearch)) {
String result1 = ("Warning!: ") + result.concat(" found");
return result1;
} else {
String result2 = ("I have found: ") + result.concat(" check it");
return result2;
}
//Log.d(TAG, result);
//return result;
} catch (Exception ex) {
Log.d(TAG, "Error: " + ex + "\n" + ex.getMessage());
}
return null;
}
@Override
protected void onPostExecute(String s) {
if(s == null || bmp == null || context == null)
return;
ImageDialog.New()
.addBitmap(bmp)
.addTitle(s)
.show(context.getFragmentManager(), TAG);
super.onPostExecute(s);
}
}
编辑：我忘了添加微量
08-25 10:41:25.210 6311-7176/com.fastnetserv.app D/DBG_com.fastnetserv.app.TessAsyncEngine: Error: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.String.toString()' on a null object reference
Attempt to invoke virtual method 'java.lang.String java.lang.String.toString()' on a null object reference
EDIT2的AsyncTask阿希什建议后
public class TessAsyncEngine extends AsyncTask<Void, Void, Void> {
static final String TAG = "DBG_" + TessAsyncEngine.class.getName();
private Bitmap bmp;
private Activity context;
String search;
TessAsyncEngine(String search){
this.search=search;
}
@Override
//protected String doInBackground(Object... params) {
protected Void doInBackground(Void... params){
try {
if(params.length < 2) {
Log.e(TAG, "Error passing parameter to execute - missing params");
return null;
}
if(!(params[0] instanceof Activity) || !(params[1] instanceof Bitmap)) {
Log.e(TAG, "Error passing parameter to execute(context, bitmap)");
//Log.e(TAG, "Error passing parameter " + params[0].toString() + params[1].toString());
return null;
}
context = (Activity)params[0];
bmp = (Bitmap)params[1];
if(context == null || bmp == null) {
Log.e(TAG, "Error passed null parameter to execute(context, bitmap)");
return null;
}
int rotate = 0;
if(params.length == 3 && params[2]!= null && params[2] instanceof Integer){
rotate = (Integer) params[2];
}
if(rotate >= -180 && rotate <= 180 && rotate != 0)
{
bmp = Tools.preRotateBitmap(bmp, rotate);
Log.d(TAG, "Rotated OCR bitmap " + rotate + " degrees");
}
TessEngine tessEngine = TessEngine.Generate(context);
bmp = bmp.copy(Bitmap.Config.ARGB_8888, true);
String result = tessEngine.detectText(bmp);
//detect words
//Bundle bundle = context.getIntent().getExtras();
//String txtSearch = bundle.getString("TextSearch");
String textSearch = new ScanFragment().txtSearch;
if (result.equalsIgnoreCase(textSearch)) {
String result1 = ("WARNING! : ") + result.concat(" found");
return result1;
} else {
String result2 = ("detected this word: ") + result.concat(" please check it");
return result2;
}
//Log.d(TAG, result);
//return result;
} catch (Exception ex) {
Log.d(TAG, "Error: " + ex + "\n" + ex.getMessage());
}
return null;
}
@Override
protected void onPostExecute(String s) {
if(s == null || bmp == null || context == null)
return;
ImageDialog.New()
.addBitmap(bmp)
.addTitle(s)
.show(context.getFragmentManager(), TAG);
super.onPostExecute(s);
}
}
CameraFragmnet
public class CameraFragment extends Fragment implements SurfaceHolder.Callback, View.OnClickListener,
Camera.PictureCallback, Camera.ShutterCallback {
static final String TAG = "DBG_" + MainActivity.class.getName();
Button shutterButton;
Button focusButton;
FocusBoxView focusBox;
SurfaceView cameraFrame;
CameraEngine cameraEngine;
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
private OnFragmentInteractionListener mListener;
public CameraFragment() {
// Required empty public constructor
}
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
*
* @param param1 Parameter 1.
* @param param2 Parameter 2.
* @return A new instance of fragment CameraFragment.
*/
// TODO: Rename and change types and number of parameters
public static CameraFragment newInstance(String param1, String param2) {
CameraFragment fragment = new CameraFragment();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_camera, container, false);
}
// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(Uri uri) {
if (mListener != null) {
mListener.onFragmentInteraction(uri);
}
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
try {
mListener = (OnFragmentInteractionListener) context;
} catch (ClassCastException e) {
throw new ClassCastException(context.toString()
+ " must implement OnFragmentInteractionListener");
}
}
@Override
public void onDetach() {
super.onDetach();
mListener = null;
}
// Camera Code
public String detectText(Bitmap bitmap) {
TessDataManager.initTessTrainedData(getActivity());
TessBaseAPI tessBaseAPI = new TessBaseAPI();
//String path = "/mnt/sdcard/com.fastnetserv.app/tessdata/eng.traineddata";
String path = Environment.getExternalStorageDirectory().getPath()+"/com.fastnetserv.app/files/tesseract/tessdata/eng.traineddata";
Log.d(TAG, "Check data path: " + path);
tessBaseAPI.setDebug(true);
tessBaseAPI.init(path, "ita"); //Init the Tess with the trained data file, with english language
//For example if we want to only detect numbers
//Already defined on TessEngine
//tessBaseAPI.setVariable(TessBaseAPI.VAR_CHAR_WHITELIST, "1234567890");
//tessBaseAPI.setVariable(TessBaseAPI.VAR_CHAR_BLACKLIST, "[email protected]#$%^&*()_+=-qwertyuiop[]}{POIU" +
// "YTREWQasdASDfghFGHjklJKLl;L:'\"\\|~`xcvXCVbnmBNM,./<>?");
tessBaseAPI.setImage(bitmap);
String text = tessBaseAPI.getUTF8Text();
//Log.d(TAG, "Got data: " + result);
tessBaseAPI.end();
return text;
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
Log.d(TAG, "Surface Created - starting camera");
if (cameraEngine != null && !cameraEngine.isOn()) {
cameraEngine.start();
}
if (cameraEngine != null && cameraEngine.isOn()) {
Log.d(TAG, "Camera engine already on");
return;
}
cameraEngine = CameraEngine.New(holder);
cameraEngine.start();
Log.d(TAG, "Camera engine started");
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
}
@Override
public void onResume() {
super.onResume();
cameraFrame = (SurfaceView) getActivity().findViewById(R.id.camera_frame);
shutterButton = (Button) getActivity().findViewById(R.id.shutter_button);
focusBox = (FocusBoxView) getActivity().findViewById(R.id.focus_box);
focusButton = (Button) getActivity().findViewById(R.id.focus_button);
shutterButton.setOnClickListener(this);
focusButton.setOnClickListener(this);
SurfaceHolder surfaceHolder = cameraFrame.getHolder();
surfaceHolder.addCallback(this);
surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
cameraFrame.setOnClickListener(this);
}
@Override
public void onPause() {
super.onPause();
if (cameraEngine != null && cameraEngine.isOn()) {
cameraEngine.stop();
}
SurfaceHolder surfaceHolder = cameraFrame.getHolder();
surfaceHolder.removeCallback(this);
}
@Override
public void onClick(View v) {
if(v == shutterButton){
if(cameraEngine != null && cameraEngine.isOn()){
cameraEngine.takeShot(this, this, this);
}
}
if(v == focusButton){
if(cameraEngine!=null && cameraEngine.isOn()){
cameraEngine.requestFocus();
}
}
}
@Override
public void onPictureTaken(byte[] data, Camera camera) {
Log.d(TAG, "Picture taken");
if (data == null) {
Log.d(TAG, "Got null data");
return;
}
Bitmap bmp = Tools.getFocusedBitmap(getActivity(), camera, data, focusBox.getBox());
Log.d(TAG, "Got bitmap");
//new TessAsyncEngine().executeOnExecutor(AsyncTask.SERIAL_EXECUTOR, this, bmp);
new TessAsyncEngine().executeOnExecutor(AsyncTask.SERIAL_EXECUTOR, getActivity(), bmp);
}
@Override
public void onShutter() {
}
}
你逝去的只是一个参数的AsyncTask。所以'doInBackground'中的第一个'if'条件变为true，并返回'null'。 –