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您好，我首先检查 LocationManager 是否启用了 GPS

  LocationManager locationManager = (LocationManager) mContext
                .getSystemService(LOCATION_SERVICE);

        // getting GPS status
        isGPSEnabled = locationManager
                .isProviderEnabled(LocationManager.GPS_PROVIDER);

我已经使用了许可

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

现在如果没有启用 GPS，我打开一个对话框说你要启用 GPS？

      final AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setMessage("Yout GPS seems to be disabled, do you want to enable it?")
       .setCancelable(false)
       .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
           public void onClick(@SuppressWarnings("unused") final DialogInterface dialog, @SuppressWarnings("unused") final int id) {
               startActivity(new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS));
           }
       })
       .setNegativeButton("No", new DialogInterface.OnClickListener() {
           public void onClick(final DialogInterface dialog, @SuppressWarnings("unused") final int id) {
                dialog.cancel();
           }
       });
final AlertDialog alert = builder.create();
alert.show();

但我在我的 logcat 中得到空指针异常如下

    09-09 09:46:04.599: W/System.err(935): java.lang.NullPointerException
    09-09 09:46:04.599: W/System.err(935):  at android.content.ContextWrapper.getSystemService(ContextWrapper.java:363)
    09-09 09:46:04.599: W/System.err(935):  at com.android.internal.app.AlertController$AlertParams.<init>(AlertController.java:742)
    09-09 09:46:04.599: W/System.err(935):  at android.app.AlertDialog$Builder.<init>(AlertDialog.java:283)
    09-09 09:46:04.599: W/System.err(935):  at android.app.AlertDialog$Builder.<init>(AlertDialog.java:274)
    09-09 09:46:04.599: W/System.err(935):  at com.eheuristics.android.diegodeals.googleplacesandmaps.GPSTracker.turnGPSOn(GPSTracker.java:110)
    09-09 09:46:04.599: W/System.err(935):  at com.eheuristics.android.diegodeals.googleplacesandmaps.GPSTracker.getLocation(GPSTracker.java:63)
    09-09 09:46:04.599: W/System.err(935):  at com.eheuristics.android.diegodeals.googleplacesandmaps.GPSTracker.<init>(GPSTracker.java:45)
     09-09 09:46:04.599: W/System.err(935):     at com.eheuristics.android.diegodeals.NearestLocation.onCreate(NearestLocation.java:79)
   09-09 09:46:04.599: W/System.err(935):   at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
   09-09 09:46:04.599: W/System.err(935):   at android app.ActivityThread.performLaunchActivity(ActivityThread.java:1722)
   09-09 09:46:04.599: W/System.err(935):   at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1784)
   09-09 09:46:04.599: W/System.err(935):   at android.app.ActivityThread.access$1500(ActivityThread.java:123)
    09-09 09:46:04.599: W/System.err(935):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:939)
   09-09 09:46:04.599: W/System.err(935):   at android.os.Handler.dispatchMessage(Handler.java:99)
    09-09 09:46:04.599: W/System.err(935):  at android.os.Looper.loop(Looper.java:130)
    09-09 09:46:04.609: W/System.err(935):  at android.app.ActivityThread.main(ActivityThread.java:3835)
   09-09 09:46:04.609: W/System.err(935):   at java.lang.reflect.Method.invokeNative(Native Method)
   09-09 09:46:04.609: W/System.err(935):   at java.lang.reflect.Method.invoke(Method.java:507)
   09-09 09:46:04.609: W/System.err(935):   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:864)
4

1 回答 1

1

尝试使用 getApplicationContext() 而不是 mContext。

于 2012-09-09T06:36:36.327 回答