Android Intent.getStringExtra（）在BroadcastReceiver中返回null

Question

我做了一個服務，它在位置發生變化之後創建一個意向，並將位置數據放入其中。

intent.putExtra("Latitude", String.valueOf(loc.getLatitude())); //Double 
      intent.putExtra("Longitude", String.valueOf(loc.getLongitude())); //Double 
      intent.putExtra("Provider", loc.getProvider()); //String 
      intent.putExtra("Altitude", loc.getAltitude());//Double 
      intent.putExtra("Accuracy", loc.getAccuracy()); //float 
      intent.putExtra("Speed", loc.getSpeed()); //float 

現在，我有一個BroadcastReceiver每30秒被髮射一次，以便將該信息發佈到服務器。然而，當我試圖讓意圖：

 Intent myIntent = new Intent(context, GPSService.class); //GPSService is the service 
     String lat = (String) myIntent.getExtras().get("Latitude"); 
     String longi = (String) myIntent.getExtras().get("Longitude"); 

我得到了NullPointerException

試圖調用虛擬方法java.lang.Object繼承 android.os.Bundle.get（java.lang中.String）'爲null對象引用

這是爲什麼？我檢查了其他解決方案：有人說是否將正確的Dateformat轉換爲意圖（在這種情況下是String），我曾這樣做過，有人說使用getIntent().getExtras().getString("aKey");我也嘗試過，如上所述，但我仍然從String中獲得null。

將它傳遞給broadcastreceiver時必須有一些問題，因爲我在做了intent.putExtra()之後記錄了這些值，而且它們絕對不是null。

編輯：

GPSService：

package com.dandddeveloper.alarmisto; 

import android.app.Service; 
import android.content.Context; 
import android.content.Intent; 
import android.location.Location; 
import android.location.LocationListener; 
import android.location.LocationManager; 
import android.os.Bundle; 
import android.os.IBinder; 
import android.util.Log; 
import android.widget.Toast; 

public class GPSService extends Service 
{ 
    public static final String BROADCAST_ACTION = "Hello World"; 
    private static final int TWO_MINUTES = 1000 * 60 * 2; 
    public LocationManager locationManager; 
    public MyLocationListener listener; 
    public Location previousBestLocation = null; 

    Intent intent; 
    int counter = 0; 

    @Override 
    public void onCreate() 
    { 
     super.onCreate(); 
     intent = new Intent(BROADCAST_ACTION); 
    } 

    @Override 
    public void onStart(Intent intent, int startId) 
    { 
     locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE); 
     listener = new MyLocationListener(); 
     //locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 4000, 0, listener); 
     locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 4000, 0, listener); 
    } 

    @Override 
    public IBinder onBind(Intent intent) 
    { 
     return null; 
    } 

    protected boolean isBetterLocation(Location location, Location currentBestLocation) { 
     if (currentBestLocation == null) { 
      // A new location is always better than no location 
      return true; 
     } 

     // Check whether the new location fix is newer or older 
     long timeDelta = location.getTime() - currentBestLocation.getTime(); 
     boolean isSignificantlyNewer = timeDelta > TWO_MINUTES; 
     boolean isSignificantlyOlder = timeDelta < -TWO_MINUTES; 
     boolean isNewer = timeDelta > 0; 

     // If it's been more than two minutes since the current location, use the new location 
     // because the user has likely moved 
     if (isSignificantlyNewer) { 
      return true; 
      // If the new location is more than two minutes older, it must be worse 
     } else if (isSignificantlyOlder) { 
      return false; 
     } 

     // Check whether the new location fix is more or less accurate 
     int accuracyDelta = (int) (location.getAccuracy() - currentBestLocation.getAccuracy()); 
     boolean isLessAccurate = accuracyDelta > 0; 
     boolean isMoreAccurate = accuracyDelta < 0; 
     boolean isSignificantlyLessAccurate = accuracyDelta > 200; 

     // Check if the old and new location are from the same provider 
     boolean isFromSameProvider = isSameProvider(location.getProvider(), 
       currentBestLocation.getProvider()); 

     // Determine location quality using a combination of timeliness and accuracy 
     if (isMoreAccurate) { 
      return true; 
     } else if (isNewer && !isLessAccurate) { 
      return true; 
     } else if (isNewer && !isSignificantlyLessAccurate && isFromSameProvider) { 
      return true; 
     } 
     return false; 
    } 



    /** Checks whether two providers are the same */ 
    private boolean isSameProvider(String provider1, String provider2) { 
     if (provider1 == null) { 
      return provider2 == null; 
     } 
     return provider1.equals(provider2); 
    } 



    @Override 
    public void onDestroy() { 
     // handler.removeCallbacks(sendUpdatesToUI); 
     super.onDestroy(); 
     Log.v("STOP_SERVICE", "DONE"); 
     locationManager.removeUpdates(listener); 
    } 

    public static Thread performOnBackgroundThread(final Runnable runnable) { 
     final Thread t = new Thread() { 
      @Override 
      public void run() { 
       try { 
        runnable.run(); 
       } finally { 

       } 
      } 
     }; 
     t.start(); 
     return t; 
    } 




    public class MyLocationListener implements LocationListener 
    { 

     public void onLocationChanged(final Location loc) 
     { 
      Log.i("***********************", "Location changed"); 
      if(isBetterLocation(loc, previousBestLocation)) { 
       loc.getLatitude(); 
       loc.getLongitude(); 
       intent.putExtra("Latitude", String.valueOf(loc.getLatitude())); //Double 
       intent.putExtra("Longitude", String.valueOf(loc.getLongitude())); //Double 
       intent.putExtra("Provider", loc.getProvider()); //String 
       intent.putExtra("Altitude", loc.getAltitude());//Double 
       intent.putExtra("Accuracy", loc.getAccuracy()); //float 
       intent.putExtra("Speed", loc.getSpeed()); //float 
       intent.putExtra("Bearing", loc.getBearing()); //float 
       Log.v("LOC", String.valueOf(loc.getLatitude())); 
       Log.v("LOC", String.valueOf(loc.getLongitude())); 
       Log.v("LOC", loc.getProvider()); 
       Log.v("LOC", String.valueOf(loc.getAltitude())); 
       Log.v("LOC", String.valueOf(loc.getAccuracy())); 
       Log.v("LOC", String.valueOf(loc.getSpeed())); 
       Log.v("LOC", String.valueOf(loc.getBearing())); 

       sendBroadcast(intent); 

      } 
     } 

     public void onProviderDisabled(String provider) 
     { 
      Toast.makeText(getApplicationContext(), "Gps Disabled", Toast.LENGTH_SHORT).show(); 
     } 


     public void onProviderEnabled(String provider) 
     { 
      Toast.makeText(getApplicationContext(), "Gps Enabled", Toast.LENGTH_SHORT).show(); 
     } 


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

     } 

    } 
} 

調用Alarmreceiver在MainActivity：

Intent alarmIntent = new Intent(getApplicationContext(), AlarmReceiver.class); 
    pendingIntent = PendingIntent.getBroadcast(MainActivity.this, 0, alarmIntent, 0); 

manager.setExactAndAllowWhileIdle(AlarmManager.RTC_WAKEUP, timeInMillis, pendingIntent); 

Answer 1

在MainActivity類創建一個BroadcastReceiver對象如下：

private BroadcastReceiver mMessageReceiver = new BroadcastReceiver() { 
    @Override 
    public void onReceive(Context context, Intent intent) { 
     // Extract data included in the Intent 

    } 
}; 

而不是在MainActivity中使用定期檢查，而是創建一個Timer對象並使用sendBroadcast(intent)發送定時播放。

Answer 2

接收方必須有一個onreceieve方法。請使用它的意圖並使用intent.getStringExtra（「key」）;並使用它。