Ich bin neu in der Android-Entwicklung. Ich verwende eine benutzerdefinierte Arrayliste mit dem Namen "Donors" in diesem Code, aber es gibt mir einen Fehler. Ich habe den gleichen Fehler viele Male hier gesehen, aber ich bin immer noch nicht in der Lage, meine Lösung zu finden. Bitte helfen Sie. Vielen Dan

05-01 23:45:10.855 1756-3399/com.donateblood.blooddonation E/AndroidRuntime: FATAL EXCEPTION: AsyncTask #2
                                                                             Process: com.donateblood.blooddonation, PID: 1756
                                                                             java.lang.RuntimeException: An error occured while executing doInBackground()
                                                                                 at android.os.AsyncTask$3.done(AsyncTask.java:300)
                                                                                 at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
                                                                                 at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
                                                                                 at java.util.concurrent.FutureTask.run(FutureTask.java:242)
                                                                                 at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
                                                                                 at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
                                                                                 at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
                                                                                 at java.lang.Thread.run(Thread.java:818)
                                                                              Caused by: java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0
                                                                                 at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:255)
                                                                                 at java.util.ArrayList.get(ArrayList.java:308)
                                                                                 at com.donateblood.blooddonation.MainGUI.getOtherLatLong(MainGUI.java:136)
                                                                                 at com.donateblood.blooddonation.MainGUI$dbAsync.doInBackground(MainGUI.java:89)
                                                                                 at com.donateblood.blooddonation.MainGUI$dbAsync.doInBackground(MainGUI.java:84)
                                                                                 at android.os.AsyncTask$2.call(AsyncTask.java:288)
                                                                                 at java.util.concurrent.FutureTask.run(FutureTask.java:237)
                                                                                 at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231) 
                                                                                 at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112) 
                                                                                 at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587) 
                                                                                 at java.lang.Thread.run(Thread.java:818) 
05-01 23:45:11.525 1756-1756/com.donateblood.blooddonation E/WindowManager: android.view.WindowLeaked: Activity com.donateblood.blooddonation.MainGUI has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView{28ea9195 V.E..... R......D 0,0-1026,348} that was originally added here
                                                                                at android.view.ViewRootImpl.<init>(ViewRootImpl.java:382)
                                                                                at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:261)
                                                                                at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:69)
                                                                                at android.app.Dialog.show(Dialog.java:298)
                                                                                at com.donateblood.blooddonation.MainGUI$dbAsync.onPreExecute(MainGUI.java:100)
                                                                                at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:587)
                                                                                at android.os.AsyncTask.execute(AsyncTask.java:535)
                                                                                at com.donateblood.blooddonation.MainGUI$1.onClick(MainGUI.java:63)
                                                                                at android.view.View.performClick(View.java:4785)
                                                                                at android.view.View$PerformClick.run(View.java:19858)
                                                                                at android.os.Handler.handleCallback(Handler.java:739)
                                                                                at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                                at android.os.Looper.loop(Looper.java:155)
                                                                                at android.app.ActivityThread.main(ActivityThread.java:5696)
                                                                                at java.lang.reflect.Method.invoke(Native Method)
                                                                                at java.lang.reflect.Method.invoke(Method.java:372)
                                                                                at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1028)
                                                                                at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:823)
05-01 23:45:47.083 1756-3399/com.donateblood.blooddonation D/Process: killProcess, pid=1756
05-01 23:45:47.083 1756-3399/com.donateblood.blooddonation D/Process: com.android.internal.os.RuntimeInit$UncaughtHandler.uncaughtException:138 java.lang.ThreadGroup.uncaughtException:693 java.lang.ThreadGroup.uncaughtException:690 

package com.donateblood.blooddonation;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.MenuItem;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.Toast;

import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.DBCursor;
import com.mongodb.DBObject;

import java.util.ArrayList;
import java.util.List;

import butterknife.ButterKnife;
import butterknife.InjectView;

/**
 * Created by YouCaf Iqbal on 4/6/2016.
 */
public class MainGUI extends AppCompatActivity {
    public static List<DonorPerson> Donors = new ArrayList<DonorPerson>();
    @InjectView(R.id.findppl) Button _findButton;
    GPSTracker gps;
    private double latitude;
    private double longitude;
    DB db; String test="";
    DBCursor cursor;
    DBCollection collection;
    Database dataobj = new Database();
    ArrayList allPPLlat = new ArrayList();
    ArrayList allPPLlong = new ArrayList();
    ArrayList allPPLNumbers = new ArrayList();
    ArrayList allPPLNames = new ArrayList();
    ArrayList allPPLImages = new ArrayList();
    ArrayList allPPLEmails = new ArrayList();
    ArrayList SelectedPPLlat = new ArrayList();
    ArrayList SelectedPPLlong = new ArrayList();
    public Spinner mySpinner;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.maingui);
        ButterKnife.inject(this);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        Spinner spinner =(Spinner) findViewById(R.id.spinner);
        String[] list = getResources().getStringArray(R.array.blood_type);
        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,R.layout.spinner_layout,R.id.txt,list);
        spinner.setAdapter(adapter);
        _findButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                getCurrentLatLong();
                dbAsync thrd = new dbAsync();
                thrd.execute();
            }
            //distance=Distance(lablat, lablong, curlat, curlong);
        });
    }
    public void getCurrentLatLong(){
        gps = new GPSTracker(MainGUI.this);
        if (gps.canGetLocation()) {
            latitude = gps.getLatitude();
            longitude = gps.getLongitude();
        }
    }
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if(item.getItemId()==android.R.id.home){
            finish();
        }
        return super.onOptionsItemSelected(item);
    }


    public class dbAsync extends AsyncTask<Void,Void,Void>{
        private ProgressDialog pDialog;

        @Override
        protected Void doInBackground(Void... voids) {
            getOtherLatLong();
            return null;
        }

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pDialog = new ProgressDialog(MainGUI.this);
            pDialog.setMessage("Searching people nearby...");
            pDialog.setIndeterminate(false);
            pDialog.setCancelable(true);
            pDialog.show();
        }

        @Override
        protected void onPostExecute(Void aVoid) {

            super.onPostExecute(aVoid);
            pDialog.dismiss();
            Intent intent = new Intent(getApplicationContext(), PeopleList.class);
            startActivity(intent);
           // Toast.makeText(getBaseContext(), "Near by latitudes "+SelectedPPLlat, Toast.LENGTH_LONG).show();
           // Toast.makeText(getBaseContext(), "Near by longitudes "+SelectedPPLlong, Toast.LENGTH_LONG).show();
        }
    }

    public void getOtherLatLong() {
        db = dataobj.getconnection();
        collection = db.getCollection("UserDetails");
        cursor = collection.find();
        while (cursor.hasNext()) {
            DBObject doc = cursor.next();
            // Lats longs used in the next for Loop for calculation distances
            allPPLlat.add(doc.get("lat"));
            allPPLlong.add(doc.get("long"));
            // All these other arraylists are used to store object of a donor person
            allPPLEmails.add(doc.get("number").toString());
            allPPLNames.add(doc.get("Name").toString());
            allPPLImages.add(doc.get("image").toString());
            allPPLEmails.add(doc.get("email").toString());

        }

        for(int i =0;i<allPPLlat.size();i++){
           double Dist= Distance((double)allPPLlat.get(i),(double)allPPLlong.get(i),latitude,longitude);
            Dist=Dist/1000;
            if(Dist<20){
                Donors.add(new DonorPerson(""+allPPLNames.get(i)+"", ""+allPPLEmails.get(i)+"" ,""+allPPLNumbers.get(i)+"" ,""+allPPLImages.get(i)+""));
            }
        }
    }

    public double Distance(double lat1, double lon1, double lat2, double lon2) {
        double R = 6371.0; // km
        double dLat = (lat2 - lat1) * Math.PI / 180.0;
        double dLon = (lon2 - lon1) * Math.PI / 180.0;
        lat1 = lat1 * Math.PI / 180.0;
        lat2 = lat2 * Math.PI / 180.0;

        double a = Math.sin(dLat / 2.0) * Math.sin(dLat / 2.0) +
                Math.sin(dLon / 2.0) * Math.sin(dLon / 2.0) * Math.cos(lat1) * Math.cos(lat2);
        double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
        double d = R * c;
        return d * 1000; // return distance in m
    }
}