我一直试图将一些下载的内容从我的活动中传递给徒劳的片段。我已经分解了步骤，看在哪里弹出错误，并得出了一些结论：（i）在片段和活动之间进行切换，反之亦然。 （ii）仅当我输入一些数据并尝试使用捆绑将其传递给活动中的片段时，问题才会出现。 这是我的片段代码： 包com.antojoh.bottomnavig;
import android.content.Context;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.widget.CardView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;
import java.util.ArrayList;
/**
* A simple {@link Fragment} subclass.
* Activities that contain this fragment must implement the
* {@link ShopFragment.OnFragmentInteractionListener} interface
* to handle interaction events.
* Use the {@link ShopFragment#newInstance} factory method to
* create an instance of this fragment.
*/
public class ShopFragment extends Fragment {
// 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";
static ArrayList<String> arrayList = new ArrayList<String>();
static ArrayAdapter<String> arrayAdapter;
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
private OnFragmentInteractionListener mListener;
public ShopFragment() {
// 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 ShopFragment.
*/
// TODO: Rename and change types and number of parameters
public static ShopFragment newInstance(String param1, String param2) {
ShopFragment fragment = new ShopFragment();
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) {
View view = inflater.inflate(R.layout.fragment_shop, container, false);
ListView listView = (ListView) view.findViewById(R.id.list);
arrayAdapter = new ArrayAdapter<String>(getContext(), android.R.layout.simple_list_item_checked, arrayList);
listView.setAdapter(arrayAdapter);
CardView cardView = (CardView) view.findViewById(R.id.cardView);
cardView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent intent = new Intent(getContext(), BarcodeActivity.class);
startActivity(intent);
}
});
Bundle bundle = this.getArguments();
if (bundle != null){
String value = bundle.getString("coder");
arrayList.add(value);
arrayAdapter.notifyDataSetChanged();
}
return view;
}
// 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);
if (context instanceof OnFragmentInteractionListener) {
mListener = (OnFragmentInteractionListener) context;
} else {
Toast.makeText(context, "Shop Fragment", Toast.LENGTH_SHORT).show();
}
}
@Override
public void onDetach() {
super.onDetach();
mListener = null;
}
/**
* This interface must be implemented by activities that contain this
* fragment to allow an interaction in this fragment to be communicated
* to the activity and potentially other fragments contained in that
* activity.
* <p>
* See the Android Training lesson <a href=
* "http://developer.android.com/training/basics/fragments/communicating.html"
* >Communicating with Other Fragments</a> for more information.
*/
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
void onFragmentInteraction(Uri uri);
}
}
这是我的活动代码：
package com.antojoh.bottomnavig;
import android.Manifest;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.AsyncTask;
import android.os.Vibrator;
import android.support.annotation.NonNull;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.util.SparseArray;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import com.google.android.gms.vision.CameraSource;
import com.google.android.gms.vision.Detector;
import com.google.android.gms.vision.barcode.Barcode;
import com.google.android.gms.vision.barcode.BarcodeDetector;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class BarcodeActivity extends AppCompatActivity {
SurfaceView cameraPreview;
private EditText editText;
BarcodeDetector barcodeDetector;
CameraSource cameraSource;
final int RequestCameraPermissionID = 1001;
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
switch (requestCode) {
case RequestCameraPermissionID: {
if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
try {
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
return;
}
cameraSource.start(cameraPreview.getHolder());
} catch (IOException e) {
e.printStackTrace();
}
}
}
break;
}
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_barcode);
editText = (EditText) findViewById(R.id.editText);
cameraPreview = (SurfaceView) findViewById(R.id.cameraPreview);
barcodeDetector = new BarcodeDetector.Builder(this)
.setBarcodeFormats(Barcode.UPC_A | Barcode.UPC_E | Barcode.EAN_8 | Barcode.EAN_13 | Barcode.CODE_128 | Barcode.CODE_39 | Barcode.CODE_93 | Barcode.ISBN | Barcode.ITF)
.build();
cameraSource = new CameraSource.Builder(this, barcodeDetector)
.setRequestedPreviewSize(640, 480)
.setAutoFocusEnabled(true)
.build();
cameraPreview.getHolder().addCallback(new SurfaceHolder.Callback() {
@Override
public void surfaceCreated(SurfaceHolder surfaceHolder) {
if (ActivityCompat.checkSelfPermission(getApplicationContext(), Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(BarcodeActivity.this, new String[]{Manifest.permission.CAMERA}, RequestCameraPermissionID);
return;
}
try {
cameraSource.start(cameraPreview.getHolder());
}catch (IOException e){
e.printStackTrace();
}
}
@Override
public void surfaceChanged(SurfaceHolder surfaceHolder, int i, int i1, int i2) {
}
@Override
public void surfaceDestroyed(SurfaceHolder surfaceHolder) {
cameraSource.stop();
}
});
barcodeDetector.setProcessor(new Detector.Processor<Barcode>() {
@Override
public void release() {
}
@Override
public void receiveDetections(Detector.Detections<Barcode> detections) {
final SparseArray<Barcode> qrcodes = detections.getDetectedItems();
if (qrcodes.size() != 0){
update(qrcodes.valueAt(0).rawValue);
}
}
});
}
public class DownloadTask extends AsyncTask<String, Void, String>{
@Override
protected String doInBackground(String... urls) {
String result="";
URL url;
HttpURLConnection urlConnection=null;
try {
url = new URL(urls[0]);
urlConnection = (HttpURLConnection)url.openConnection();
InputStream in = urlConnection.getInputStream();
InputStreamReader reader = new InputStreamReader(in);
int data = reader.read();
while (data != -1){
char current = (char) data;
result += current;
data = reader.read();
}
return result;
}catch (Exception e){
e.printStackTrace();
}
return null;
}
}
public void update(String string) {
String result = "";
DownloadTask task = new DownloadTask();
try {
result = task.execute("https://www.barcodable.com/ean/" + string).get();
} catch (Exception e) {
e.printStackTrace();
}
Pattern p = Pattern.compile("<title>UPC (.*?)</title>");
Matcher m = p.matcher(result);
while (m.find()) {
if (m.group(1) != null) {
Bundle bundle = new Bundle();
bundle.putString("coder", m.group(1));
ShopFragment shopFragment = new ShopFragment();
shopFragment.setArguments(bundle);
getSupportFragmentManager().beginTransaction().replace(R.id.cont, shopFragment).commit();
}
}
}
public void enter(View view){
update(editText.getText().toString());
}
}
还有Logcat：
08-14 14:46:03.037 5419-5460/com.antojoh.bottomnavig W/System.err: java.io.FileNotFoundException: https://www.barcodable.com/ean/9781614272137
at com.android.okhttp.internal.huc.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:250)
at com.android.okhttp.internal.huc.DelegatingHttpsURLConnection.getInputStream(DelegatingHttpsURLConnection.java:210)
at com.android.okhttp.internal.huc.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java)
at com.antojoh.bottomnavig.BarcodeActivity$DownloadTask.doInBackground(BarcodeActivity.java:144)
at com.antojoh.bottomnavig.BarcodeActivity$DownloadTask.doInBackground(BarcodeActivity.java:134)
at android.os.AsyncTask$2.call(AsyncTask.java:304)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:243)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133)
08-14 14:46:03.038 5419-5460/com.antojoh.bottomnavig W/System.err: at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607)
at java.lang.Thread.run(Thread.java:761)
08-14 14:46:03.041 5419-5419/com.antojoh.bottomnavig E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.antojoh.bottomnavig, PID: 5419
java.lang.IllegalStateException: Could not execute method for android:onClick
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:389)
at android.view.View.performClick(View.java:5610)
at android.view.View$PerformClick.run(View.java:22265)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:384)
at android.view.View.performClick(View.java:5610)
at android.view.View$PerformClick.run(View.java:22265)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
Caused by: java.lang.NullPointerException: Attempt to invoke interface method 'int java.lang.CharSequence.length()' on a null object reference
at java.util.regex.Matcher.reset(Matcher.java:995)
at java.util.regex.Matcher.<init>(Matcher.java:174)
at java.util.regex.Pattern.matcher(Pattern.java:1006)
at com.antojoh.bottomnavig.BarcodeActivity.update(BarcodeActivity.java:171)
at com.antojoh.bottomnavig.BarcodeActivity.enter(BarcodeActivity.java:190)
at java.lang.reflect.Method.invoke(Native Method)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:384)
at android.view.View.performClick(View.java:5610)
at android.view.View$PerformClick.run(View.java:22265)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
答案 0 :(得分：0)
这很简单。该网站一次不接受太多请求（我接受了）。因此，我要做的就是要么切换到另一个网站，要么等待特定时间以获得再次请求访问的权限！谢谢！