場所の許可を求めた後すぐにクラッシュします

Question

私はこれに似た質問をしましたが、それらのすべてにはcatlogが含まれていないので誰も本当に助けませんでした。私はここにそれを含めるようにしたので、あなたが助けてくれることを願っています！基本的には、私はそれを許可すると言う場所の許可を私に促すアプリを開くとすぐに。はい、私はヒットすると、アプリケーションがクラッシュします！ここ

package com.worden.jason.sample; 

import android.Manifest; 
import android.content.DialogInterface; 
import android.content.Intent; 
import android.content.pm.PackageManager; 
import android.location.Location; 
import android.location.LocationListener; 
import android.location.LocationManager; 
import android.support.annotation.NonNull; 
import android.support.v4.app.ActivityCompat; 
import android.support.v4.content.ContextCompat; 
import android.support.v7.app.AlertDialog; 
import android.support.v7.app.AppCompatActivity; 
import android.os.Bundle; 
import android.view.View; 

public class MainActivity extends AppCompatActivity implements LocationListener { 
    LocationManager locationManager; 
    public static final int MY_PERMISSIONS_REQUEST_LOCATION = 99; 
    String provider; 
    public void Analysis(View view) { 
     Intent intent = new Intent(MainActivity.this,Analysis.class); 
     startActivity(intent); 
     finish(); 
    } 

    public void Tips(View view) { 
     Intent intent = new Intent(MainActivity.this,Tips.class); 
     startActivity(intent); 
     finish(); 
    } 

    public boolean checkLocationPermission() { 
     if (ContextCompat.checkSelfPermission(this, 
       Manifest.permission.ACCESS_FINE_LOCATION) 
       != PackageManager.PERMISSION_GRANTED) { 

      // Should we show an explanation? 
      if (ActivityCompat.shouldShowRequestPermissionRationale(this, 
        Manifest.permission.ACCESS_FINE_LOCATION)) { 

       // Show an explanation to the user *asynchronously* -- don't block 
       // this thread waiting for the user's response! After the user 
       // sees the explanation, try again to request the permission. 
       new AlertDialog.Builder(this) 
         .setTitle(R.string.TileLocation) 
         .setMessage(R.string.TextLocation) 
         .setPositiveButton(R.string.Positive, new DialogInterface.OnClickListener() { 
          @Override 
          public void onClick(DialogInterface dialogInterface, int i) { 
           //Prompt the user once explanation has been shown 
           ActivityCompat.requestPermissions(MainActivity.this, 
             new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, 
             MY_PERMISSIONS_REQUEST_LOCATION); 
          } 
         }) 
         .create() 
         .show(); 
      } else { 
       ActivityCompat.requestPermissions(this, 
         new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, 
         MY_PERMISSIONS_REQUEST_LOCATION); 
      } 
      return false; 
     } else { 
      return true; 
     } 
    } 

    @Override 
    public void onRequestPermissionsResult(int requestCode, 
              @NonNull String permissions[], @NonNull int[] grantResults) { 
     switch (requestCode) { 
      case MY_PERMISSIONS_REQUEST_LOCATION: { 
       // If request is cancelled, the result arrays are empty. 
       if (grantResults.length > 0 
         && grantResults[0] == PackageManager.PERMISSION_GRANTED) { 

        // location-related task you need to do. 

        if (ContextCompat.checkSelfPermission(this, 
          Manifest.permission.ACCESS_FINE_LOCATION) 
          == PackageManager.PERMISSION_GRANTED) { 


         locationManager.requestLocationUpdates(provider, 400, 1, this); 
        } 

       } else { 

        // permission denied, boo! Disable the 
       } 
       return; 
      } 

     } 
    } 

    @Override 
    public void onLocationChanged(Location location) { 

    } 

    @Override 
    public void onStatusChanged(String provider, int status, Bundle extras) { 

    } 

    @Override 
    public void onProviderEnabled(String provider) { 

    } 

    @Override 
    public void onProviderDisabled(String provider) { 

    } 

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

     if (checkLocationPermission()) { 
      if (ContextCompat.checkSelfPermission(this, 
        Manifest.permission.ACCESS_FINE_LOCATION) 
        == PackageManager.PERMISSION_GRANTED) { 

       //Request location updates: 
       locationManager.requestLocationUpdates(provider, 400, 1, this); 
      } 
     } 
    } 
} 

log for crash

EDIT

public class MainActivity extends AppCompatActivity implements LocationListener { 
    LocationManager locationManager; 
    public static final int MY_PERMISSIONS_REQUEST_LOCATION = 99; 
    **String GPS_PROVIDER;** 
    public void Analysis(View view) { 
     Intent intent = new Intent(MainActivity.this,Analysis.class); 
     startActivity(intent); 
     finish(); 
    } 

    public void Tips(View view) { 
     Intent intent = new Intent(MainActivity.this,Tips.class); 
     startActivity(intent); 
     finish(); 
    } 
    **@Override 
    protected void onCreate(@Nullable Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);** 
    } 

    public boolean checkLocationPermission() { 

     if (ContextCompat.checkSelfPermission(this, 
       Manifest.permission.ACCESS_FINE_LOCATION) 
       != PackageManager.PERMISSION_GRANTED) { 

      // Should we show an explanation? 
      if (ActivityCompat.shouldShowRequestPermissionRationale(this, 
        Manifest.permission.ACCESS_FINE_LOCATION)) { 

       // Show an explanation to the user *asynchronously* -- don't block 
       // this thread waiting for the user's response! After the user 
       // sees the explanation, try again to request the permission. 
       new AlertDialog.Builder(this) 
         .setTitle(R.string.TileLocation) 
         .setMessage(R.string.TextLocation) 
         .setPositiveButton(R.string.Positive, new DialogInterface.OnClickListener() { 
          @Override 
          public void onClick(DialogInterface dialogInterface, int i) { 
           //Prompt the user once explanation has been shown 
           ActivityCompat.requestPermissions(MainActivity.this, 
             new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, 
             MY_PERMISSIONS_REQUEST_LOCATION); 
          } 
         }) 
         .create() 
         .show(); 


      } else { 

       ActivityCompat.requestPermissions(this, 
         new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, 
         MY_PERMISSIONS_REQUEST_LOCATION); 
      } 
      return false; 
     } else { 
      return true; 
     } 
    } 

    @Override 
    public void onRequestPermissionsResult(int requestCode, 
              @NonNull String permissions[], @NonNull int[] grantResults) { 
     switch (requestCode) { 
      case MY_PERMISSIONS_REQUEST_LOCATION: { 
       // If request is cancelled, the result arrays are empty. 
       if (grantResults.length > 0 
         && grantResults[0] == PackageManager.PERMISSION_GRANTED) { 


        // location-related task you need to do. 

        if (ContextCompat.checkSelfPermission(this, 
          Manifest.permission.ACCESS_FINE_LOCATION) 
          == PackageManager.PERMISSION_GRANTED) { 


         locationManager.requestLocationUpdates(GPS_PROVIDER, 400, 1, this); 
        } 

       } else { 

        // permission denied, boo! Disable the 


       } 
       return; 
      } 

     } 
    } 

    @Override 
    public void onLocationChanged(Location location) { 

    } 

    @Override 
    public void onStatusChanged(String provider, int status, Bundle extras) { 

    } 

    @Override 
    public void onProviderEnabled(String provider) { 

    } 

    @Override 
    public void onProviderDisabled(String provider) { 

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

     if (checkLocationPermission()) { 
      if (ContextCompat.checkSelfPermission(this, 
        Manifest.permission.ACCESS_FINE_LOCATION) 
        == PackageManager.PERMISSION_GRANTED) { 

       //Request location updates: 
       locationManager.requestLocationUpdates(GPS_PROVIDER, 400, 1, this); 
      } 
     } 

    } 
} 

Answer 1

2つの問題：

1. あなたはlocationManagerフィールドを初期化しません。 locationManager.requestLocationUpdatesへの電話はNullPointerExceptionになります。

2. providerフィールドを初期化しません。 locationManager.requestLocationUpdatesへのあなたの電話はこれを好まない。

   protected void onCreate(@Nullable Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE); 
   } 
   

   、第二の問題を解決するあなたのproviderフィールドを捨て、代わりにLocationManager.GPS_PROVIDER（またはLocationManagerで定義された他のプロバイダのいずれか）を使用するには、次の、最初の問題を解決するこのオーバーライドを追加するには

。またはproviderフィールドを初期化します。

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デバッガでブレークポイントを設定してプログラムを実行すると、このような問題を見つけるのに適しています。別のアプローチは、ログを見ることです。–どこかに関連するスタックトレースがあると思います。

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また、あなたのマニフェストには、必要な許可を言及していることを確認します。

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />