如何在Android中修复位置，适配器和ListView错误？

嗨，大家好，我有一个棘手的错误，我无法解决。我正在开发一个列表视图，当位置服务处于活动状态时，我希望如果位置开启，我会注意时间去某个地方，当位置服务关闭时，我将显示一条消息而不是时间。没什么特别的。但我有一个棘手的错误，如果我有GPS，如此精细的位置，工作，如果我关闭所有位置，工作，但如果我有粗略的位置活动，应用程序崩溃...这非常棘手。在我的代码和我的logcat下面。多谢你们。如何在Android中修复位置，适配器和ListView错误？

完整类代码：

package com.example.findmyclients; 

import java.io.FileInputStream; 
import java.util.ArrayList; 
import java.util.Arrays; 
import java.util.Collection; 
import java.util.Collections; 
import java.util.Comparator; 
import java.util.HashMap; 
import java.util.Iterator; 
import java.util.List; 
import java.util.ListIterator; 

import javax.xml.parsers.DocumentBuilder; 
import javax.xml.parsers.DocumentBuilderFactory; 

import org.w3c.dom.Document; 
import org.w3c.dom.NodeList; 
import org.w3c.dom.Element; 


import android.app.Activity; 
import android.app.ListActivity; 
import android.content.Context; 
import android.content.Intent; 
import android.location.Location; 
import android.location.LocationManager; 
import android.os.Bundle; 
import android.view.Menu; 
import android.view.MenuInflater; 
import android.view.MenuItem; 
import android.view.View; 
import android.widget.AdapterView; 
import android.widget.AdapterView.OnItemClickListener; 
import android.widget.ArrayAdapter; 
import android.widget.ListView; 
import android.widget.TextView; 
import android.widget.Toast; 

public class ListviewActivity extends Activity{ 

private ListView lista; 
private ListView listaNOGPS; 
private List<InterestPoint> listaInteressPoint; 
private List<InterestPoint> listaInteressPointNOGPS; 
private InterestPoint ip; 
private CustomListAdapter adapter; 
private CustomListAdapter adapterNOGPS; 

public String [][]ArrayTime = new String[1000][6]; //La matrice che conterrà tutti i dati relativi alla lista 

public String [][]Dati_history = new String[100][10]; 
public String [][]Dati_restaurant = new String[100][10]; 
public String [][]Dati_hotel = new String[100][10]; 
public String [][]Dati_souvenir = new String[100][10]; 
public String pathdirectory = "/sdcard/PredappioLiving/"; 

String[]file_names={"markers_history.xml", "markers_hotel.xml", "markers_restaurant.xml", "markers_souvenir.xml"}; 
String[]Array_Cat={"Monumenti","Alloggi","Ristoranti","Negozi"}; 

int nome_luogo = 0; 
int categoria = 1; 
int auto = 2; 
int piedi = 3; 
int latitude = 4; 
int longitude = 5; 

int gps_on= 0; 



    @Override 
    protected void onCreate (Bundle savedInstanceState){ 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_list); 

     final Activity thiz = this; 

     //Get ListView Object from xml 
     lista = (ListView) thiz.findViewById(R.id.lista); 
     listaNOGPS = (ListView) thiz.findViewById(R.id.lista); 

     GPSTracker gpstrack = new GPSTracker(this); 
     if (gpstrack.canGetLocation()) { 
      gps_on = 1; 
     } 

     /* - - - Costruzione della matrice dall'xml - - - */ 
     /* - - - - - - - - - - - - - - - - - - - - - - - -*/ 
     int file_choice=-1; 
     int n = 0; //mi serve per riempire bene tutta la matrice 
     for (int i = 0; i<file_names.length; i++) 
     { 
      String file_path = pathdirectory+file_names[i]; 
      int indice_riempimento = n; 

      int returnhistory = file_names[i].compareTo("markers_history.xml"); 
      int returnhotel = file_names[i].compareTo("markers_hotel.xml"); 
      int returnrestaurant = file_names[i].compareTo("markers_restaurant.xml"); 
      int returnsouvenir = file_names[i].compareTo("markers_souvenir.xml"); 

      if (returnhistory == 0){ 
       file_choice = 0; 
      } 
      if (returnhotel == 0){ 
       file_choice = 1; 
      } 
      if (returnrestaurant == 0){ 
       file_choice = 2; 
      } 
      if (returnsouvenir == 0){ 
       file_choice = 3; 
      } 

      // Inizio lettura da XML e popolazione della matrice 

      try 
      { 
       DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); 
       DocumentBuilder builder = factory.newDocumentBuilder(); 
       Document doc = builder.parse(new FileInputStream(file_path)); 
       doc.getDocumentElement().normalize(); 

       NodeList nodi = doc.getElementsByTagName("marker"); 



       for (int c = 0; c<nodi.getLength(); c++) 
       { 
        Element item = (Element) nodi.item(c); 
        String nome = item.getAttribute("name"); 
        String destLat = item.getAttribute("lat"); 
        String destLong = item.getAttribute("long"); 

        Double lat = Double.valueOf(destLat); 
        Double lon = Double.valueOf(destLong); 

        GPSTracker gpsTracker = new GPSTracker(this); 

        String stringMyLatitude = String.valueOf(gpsTracker.latitude); 
        String stringMyLongitude = String.valueOf(gpsTracker.longitude); 

        double currentLat = Double.parseDouble(stringMyLatitude); 
        double currentLong = Double.parseDouble(stringMyLongitude); 

        final float[]distanzadouble = new float[3]; 
        Location.distanceBetween(currentLat, currentLong, lat, lon, distanzadouble); 

        float metri = distanzadouble[0]; 
        float km = Math.round((double)metri/1000); 

        int minuti_persona = (int)Math.round(metri/125); //125 metri al minuto -> velocità media di 2,5 m/s 
        int minuti_auto = (int)Math.round(km/0.7);   //700 metri al minuto -> velocità media di 42 km/h 

        String string_min_a_piedi; 
        String string_min_in_auto; 

        if(minuti_persona <=0)   // Stampa tempo per coprire la distanza 
        { 
         string_min_a_piedi="meno di un minuto"; 
        }else 
        { 
         string_min_a_piedi=String.valueOf(minuti_persona); 
        } 

        if(minuti_auto <= 0) 
        { 
         string_min_in_auto="meno di un minuto";         
        }else 
        { 
         string_min_in_auto= String.valueOf(minuti_auto); 
        } 

        ArrayTime[c+n][nome_luogo] = nome; 
        ArrayTime[c+n][categoria] = Array_Cat[file_choice]; 
        ArrayTime[c+n][auto] = string_min_in_auto; 
        ArrayTime[c+n][piedi] = string_min_a_piedi; 


       } 

       n = n+nodi.getLength(); 


      }catch(Exception e) 
      { 
       e.printStackTrace(); 
      } 


     } 

     //Arrays.sort(ArrayTime, new ColumnComparator(0)); 




     //Stampa dell'array sulla lista - - - 

     /* 
     for(int i = 0; i<6; i++) 
     { 
      ip = new InterestPoint(); 
      ip.nome = "pippo"+i; 
      ip.categoria ="cat pippo"+i; 
      ip.apiedi = "25"; 
      ip.inauto = "10"; 
      listaInteressPoint.add(ip); 
     } 
     */ 



     final LocationManager manager = (LocationManager) getSystemService(Context.LOCATION_SERVICE); 


     if (gps_on == 1) { 

      listaInteressPoint = new ArrayList<InterestPoint>(); 

      for(int i = 0; i<n;i++) 
      { 
       ip = new InterestPoint(); 
       ip.nome = ArrayTime[i][nome_luogo]; 
       ip.categoria = "Categoria: "+ArrayTime[i][categoria]; 
       ip.inauto = "In auto: " +ArrayTime[i][auto]+ " minuti"; 
       ip.apiedi = "A piedi: " +ArrayTime[i][piedi]+ " minuti"; 
       listaInteressPoint.add(ip); 
      } 

      //Ordinamento 
      Collections.sort(listaInteressPoint, new Comparator<InterestPoint>(){ 

       @Override 
       public int compare(InterestPoint elem1, InterestPoint elem2) { 

        return elem1.inauto.compareTo(elem2.inauto); 
       } 

      }); 


     }else 
     { 

      listaInteressPointNOGPS = new ArrayList<InterestPoint>(); 

      for(int i = 0; i<n;i++) 
      { 
       ip = new InterestPoint(); 
       ip.nome = ArrayTime[i][nome_luogo]; 
       ip.categoria = "Categoria: "+ArrayTime[i][categoria]; 
       ip.inauto = "In auto: Attiva la posizione per la distanza"; 
       ip.apiedi = "A piedi: in auto e a piedi"; 
       listaInteressPointNOGPS.add(ip); 
      } 

      //Ordinamento 
      Collections.sort(listaInteressPointNOGPS, new Comparator<InterestPoint>(){ 

       @Override 
       public int compare(InterestPoint elem1, InterestPoint elem2) { 

        return elem1.nome.compareTo(elem2.nome); 
       } 

      }); 
     } 

     /* 
     //ListView Item Click Listener 
      listaNOGPS.setOnItemClickListener(new OnItemClickListener() { 


       @Override 
       public void onItemClick(AdapterView<?> parent, View view, 
         int position, long id) { 

       //ListView Clicked item index 
         int itemPosition = position; 

         InterestPoint item = adapter.getItem(position); 

         Intent piu_info = new Intent(thiz, MoreInfoActivity.class); 
         piu_info.putExtra("nome", item.nome); 
         startActivity(piu_info); 
         //ListView clicked item value 
         //int itemValue = (int) lista.getItemAtPosition(position); 

         //Show Alert 
         Toast.makeText(getApplicationContext(), "Position :"+itemPosition+" ListItem :"+ item.nome, Toast.LENGTH_LONG).show(); 

       } 
      }); 

      */ 

     //ListView Item Click Listener 
     lista.setOnItemClickListener(new OnItemClickListener() { 


      @Override 
      public void onItemClick(AdapterView<?> parent, View view, 
        int position, long id) { 

        if (gps_on == 1){ 
         //ListView Clicked item index 
         int itemPosition = position; 

         InterestPoint item = adapter.getItem(position); 

         Intent piu_info = new Intent(thiz, MoreInfoActivity.class); 
         piu_info.putExtra("nome", item.nome); 
         startActivity(piu_info); 
         //ListView clicked item value 
         //int itemValue = (int) lista.getItemAtPosition(position); 

         //Show Alert 
         Toast.makeText(getApplicationContext(), "Position :"+itemPosition+" ListItem :"+ item.nome, Toast.LENGTH_LONG).show(); 
        }else 
        { 
         //ListView Clicked item index 
         int itemPosition = position; 

         InterestPoint item = adapterNOGPS.getItem(position); 

         Intent piu_info = new Intent(thiz, MoreInfoActivity.class); 
         piu_info.putExtra("nome", item.nome); 
         startActivity(piu_info); 
         //ListView clicked item value 
         //int itemValue = (int) lista.getItemAtPosition(position); 

         //Show Alert 
         Toast.makeText(getApplicationContext(), "Position :"+itemPosition+" ListItem :"+ item.nome, Toast.LENGTH_LONG).show(); 
        } 


      } 
     }); 

    } 

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

      final LocationManager manager = (LocationManager) getSystemService(Context.LOCATION_SERVICE); 
      adapter = new CustomListAdapter(getApplicationContext(), R.layout.list_item, listaInteressPoint); 
      adapterNOGPS = new CustomListAdapter(getApplicationContext(), R.layout.list_item, listaInteressPointNOGPS); 

      if (manager.isProviderEnabled(LocationManager.GPS_PROVIDER)) { 

       lista.setAdapter(adapter); 
      }else 
      { 
       listaNOGPS.setAdapter(adapterNOGPS); 
      } 
     } 
}

logcat的：

10-28 10:53:53.106: E/AndroidRuntime(445): FATAL EXCEPTION: main 
10-28 10:53:53.106: E/AndroidRuntime(445): Process: com.example.findmyclients, PID: 445 
10-28 10:53:53.106: E/AndroidRuntime(445): java.lang.RuntimeException: Unable to resume activity {com.example.findmyclients/com.example.findmyclients.ListviewActivity}: java.lang.NullPointerException 
10-28 10:53:53.106: E/AndroidRuntime(445): at android.app.ActivityThread.performResumeActivity(ActivityThread.java:3076) 
10-28 10:53:53.106: E/AndroidRuntime(445): at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:3105) 
10-28 10:53:53.106: E/AndroidRuntime(445): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) 
10-28 10:53:53.106: E/AndroidRuntime(445): at android.app.ActivityThread.access$900(ActivityThread.java:175) 
10-28 10:53:53.106: E/AndroidRuntime(445): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1308) 
10-28 10:53:53.106: E/AndroidRuntime(445): at android.os.Handler.dispatchMessage(Handler.java:102) 
10-28 10:53:53.106: E/AndroidRuntime(445): at android.os.Looper.loop(Looper.java:146) 
10-28 10:53:53.106: E/AndroidRuntime(445): at android.app.ActivityThread.main(ActivityThread.java:5602) 
10-28 10:53:53.106: E/AndroidRuntime(445): at java.lang.reflect.Method.invokeNative(Native Method) 
10-28 10:53:53.106: E/AndroidRuntime(445): at java.lang.reflect.Method.invoke(Method.java:515) 
10-28 10:53:53.106: E/AndroidRuntime(445): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283) 
10-28 10:53:53.106: E/AndroidRuntime(445): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099) 
10-28 10:53:53.106: E/AndroidRuntime(445): at dalvik.system.NativeStart.main(Native Method) 
10-28 10:53:53.106: E/AndroidRuntime(445): Caused by: java.lang.NullPointerException 
10-28 10:53:53.106: E/AndroidRuntime(445): at android.widget.ArrayAdapter.getCount(ArrayAdapter.java:330) 
10-28 10:53:53.106: E/AndroidRuntime(445): at android.widget.ListView.setAdapter(ListView.java:486) 
10-28 10:53:53.106: E/AndroidRuntime(445): at com.example.findmyclients.ListviewActivity.onResume(ListviewActivity.java:356) 
10-28 10:53:53.106: E/AndroidRuntime(445): at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1198) 
10-28 10:53:53.106: E/AndroidRuntime(445): at android.app.Activity.performResume(Activity.java:5530) 
10-28 10:53:53.106: E/AndroidRuntime(445): at android.app.ActivityThread.performResumeActivity(ActivityThread.java:3066) 
10-28 10:53:53.106: E/AndroidRuntime(445): ... 12 more 
10-28 10:53:53.161: I/Process(445): Sending signal. PID: 445 SIG: 9

PS：凭借粗略位置变量 “gps_on” 被设定为 “1” 正确

来源

2014-10-28 Pierpaolo Ercoli

请删除你的标题的 “解决” 标签：HTTP：//meta.stackexchange .COM /问题/ 116101/IS-IT-OK-到附加解决到的标题对的一个问题。 – mithrop 2014-10-28 11:09:20

另外我看到你编辑你的代码发布它更正。你不应该。有类似问题的人会来到这里，并且随着你的编辑，没有人会明白答案在说什么。）请阅读[ask]了解更多信息;） – mithrop 2014-10-28 11:10:46

1。

if (gps_on == 1) { 

      listaInteressPoint = new ArrayList<InterestPoint>(); 
//rest of the code 
} else { 
      listaInteressPointNOGPS = new ArrayList<InterestPoint>(); 
//rest of the code 
}

2.PS：有了粗略的位置变量 “gps_on” 设置为 “1” 正确

所以

3.从onResume()

adapter = new CustomListAdapter(getApplicationContext(), R.layout.list_item, listaInteressPoint); 
      adapterNOGPS = new CustomListAdapter(getApplicationContext(), R.layout.list_item, listaInteressPointNOGPS); 

      if (manager.isProviderEnabled(LocationManager.GPS_PROVIDER)) { 

       lista.setAdapter(adapter); 
      }else 
      { 
       listaNOGPS.setAdapter(adapterNOGPS); 
      }

您得到的错误是getCount()的list已初始化但为空，未填充。在这种情况下，gps_on==1因此listaInteressPointNOGPS未被访问。

您可以更改onResume()中的if，并检查一个或一个条件可能...特别是在粗略位置激活的情况下。

重要线路从您的logcat：

10-28 10:53:53.106: E/AndroidRuntime(445): Caused by: java.lang.NullPointerException 
10-28 10:53:53.106: E/AndroidRuntime(445): at android.widget.ArrayAdapter.getCount(ArrayAdapter.java:330) 
10-28 10:53:53.106: E/AndroidRuntime(445): at android.widget.ListView.setAdapter(ListView.java:486) 
10-28 10:53:53.106: E/AndroidRuntime(445): at com.example.findmyclients.ListviewActivity.onResume(ListviewActivity.java:356)

检查哪一个是线356从ListviewActivity.java

来源

2014-10-28 10:20:49 user2450263

没有什么可做的:( – 2014-10-28 10:28:25

这是你班上的356行吗？把它放在试试看，你会知道 – user2450263 2014-10-28 10:32:54

我解决了你的意见!!谢谢，我更新我的问题：D – 2014-10-28 10:56:37

如何在Android中修复位置，适配器和ListView错误？

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