안드로이드 애플 리케이션의 지오 코딩

Question

어플 리케이션을 실행할 때마다 null 포인터 예외가 발생하는 이유를 알아낼 수 없습니다.이 안드로이드 애플 리케이션은 지오 코딩을 사용하여 맵에 위치를 표시하고 표시합니다. 그러나 나는 수행하지 않았습니다. 실수가 어디 있는지 알지 못해. 제발 도와주세요! 다음과 같이 주요 활동 코드는 다음과 같습니다

package com.dutt.rishabh.locator; 

import android.location.Address; 
import android.location.Geocoder; 
import android.os.AsyncTask; 
import android.support.v4.app.FragmentActivity; 
import android.os.Bundle; 
import android.view.View; 
import android.widget.Button; 
import android.widget.EditText; 
import android.widget.Toast; 


import com.google.android.gms.maps.CameraUpdateFactory; 
import com.google.android.gms.maps.GoogleMap; 
import com.google.android.gms.maps.OnMapReadyCallback; 
import com.google.android.gms.maps.SupportMapFragment; 
import com.google.android.gms.maps.model.LatLng; 
import com.google.android.gms.maps.model.MarkerOptions; 

import java.io.IOException; 
import java.util.List; 

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback { 

    private GoogleMap mMap; 
    EditText x; 
    Button bfind; 
    String location; 
    MarkerOptions markerOptions; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_maps); 
     // Obtain the SupportMapFragment and get notified when the map is ready to be used. 
     SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager() 
       .findFragmentById(R.id.map); 
     mapFragment.getMapAsync(this); 

     bfind=(Button)findViewById(R.id.bfind); 
     View.OnClickListener findClickListener =new View.OnClickListener() { 
      @Override 
      public void onClick(View view) { 
       x=(EditText)findViewById(R.id.etsearch); 
       location=x.getText().toString(); 
       if(location!=null || location.equals("")){ 
        new GeocoderTask().execute(location); 
       } 
      } 
     }; 
     bfind.setOnClickListener(findClickListener); 



    } 
    private class GeocoderTask extends AsyncTask<String, Void, List<Address>>{ 
     @Override 
     protected List<Address> doInBackground(String... strings) { 
      Geocoder geocoder = new Geocoder(getBaseContext()); 
      List<Address> addresses=null; 
      try { 
       addresses=geocoder.getFromLocationName(strings[0],3); 
      } catch (IOException e) { 
       e.printStackTrace(); 
      } 
      return addresses; 
     } 
     @Override 
     protected void onPostExecute(List<Address> addresses){ 
      if(addresses==null || addresses.size()==0){ 
       Toast.makeText(getBaseContext(),"No location found",Toast.LENGTH_SHORT).show(); 
      } 
      mMap.clear(); 
      for(int i=0;i<addresses.size();i++){ 
       Address address= addresses.get(i); 
       LatLng latLng=new LatLng(address.getLatitude(),address.getLongitude()); 
       String addressText=String.format("%s,%s",address.getMaxAddressLineIndex()>0?address.getAddressLine(0):"",address.getCountryName()); 
       markerOptions=new MarkerOptions(); 
       markerOptions.position(latLng); 
       markerOptions.title(addressText); 

       mMap.addMarker(markerOptions); 
       if(i==0){ 
        mMap.animateCamera(CameraUpdateFactory.newLatLng(latLng)); 
       } 
      } 
     } 
    } 



    /** 
    * Manipulates the map once available. 
    * This callback is triggered when the map is ready to be used. 
    * This is where we can add markers or lines, add listeners or move the camera. In this case, 
    * we just add a marker near Sydney, Australia. 
    * If Google Play services is not installed on the device, the user will be prompted to install 
    * it inside the SupportMapFragment. This method will only be triggered once the user has 
    * installed Google Play services and returned to the app. 
    */ 
    @Override 
    public void onMapReady(GoogleMap googleMap) { 
     mMap = googleMap; 

     // Add a marker in Sydney and move the camera 
     LatLng sydney = new LatLng(-34, 151); 
     mMap.addMarker(new MarkerOptions().position(sydney).title("Marker in Sydney")); 
     mMap.moveCamera(CameraUpdateFactory.newLatLng(sydney)); 
    } 
} 

그래서 내가 이해할 수있는 내 실수를 언급 친절하게 도와주세요. 다음은 logcat입니다 :

07-26 15:02:02.264 30388-30388/com.dutt.rishabh.locator E/AndroidRuntime: FATAL EXCEPTION: main 
                      Process: com.dutt.rishabh.locator, PID: 30388 
                      java.lang.NullPointerException 
                       at com.dutt.rishabh.locator.MapsActivity$GeocoderTask.onPostExecute(MapsActivity.java:75) 
                       at com.dutt.rishabh.locator.MapsActivity$GeocoderTask.onPostExecute(MapsActivity.java:57) 
                       at android.os.AsyncTask.finish(AsyncTask.java:632) 
                       at android.os.AsyncTask.access$600(AsyncTask.java:177) 
                       at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:645) 
                       at android.os.Handler.dispatchMessage(Handler.java:110) 
                       at android.os.Looper.loop(Looper.java:193) 
                       at android.app.ActivityThread.main(ActivityThread.java:5345) 
                       at java.lang.reflect.Method.invokeNative(Native Method) 
                       at java.lang.reflect.Method.invoke(Method.java:515) 
                       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:828) 
                       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:644) 
                       at dalvik.system.NativeStart.main(Native Method) 

Answer 1

NULL 체크는

if(addresses==null || addresses.size()==0){ 
       Toast.makeText(getBaseContext(),"No location found",Toast.LENGTH_SHORT).show(); 
       return; 
      } 

Answer 2

귀하의 경우 주소 목록이 null 인 것으로 보입니다. 토스트 메시지를 표시 한 후 코드 실행을 반환 할 수 있습니다. 당신이 (mMap.clear`로를 취소하기 전에 주소

for(int i=0;i<addresses.size();i++){ 
} 

또는 추가 반환

if(addresses==null || addresses.size()==0){ // Line 71 
    Toast.makeText(getBaseContext(),"No location found",Toast.LENGTH_SHORT).show(); 
    return; 
}