android - 获取位置时出现 java.lang.NullPointerException

Question

我有一些问题我无法在模拟器中重新创建，但我在 android 市场上不断收到错误报告，我不知道如何解决...任何其他可能看到它的人都非常感谢

有时会报告

java.lang.NullPointerException
at android.webkit.WebViewDatabase.getCacheTotalSize(WebViewDatabase.java:734)
at android.webkit.CacheManager.trimCacheIfNeeded(CacheManager.java:548)
at android.webkit.WebViewWorker.handleMessage(WebViewWorker.java:190)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:123)
at android.os.HandlerThread.run(HandlerThread.java:60)

有时还有这份报告

java.lang.RuntimeException: Unable to start activity ComponentInfo{polis.koll/polis.koll.WebPageLoader}: java.lang.IllegalArgumentException: provider==null
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2737)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2753)
at android.app.ActivityThread.access$2500(ActivityThread.java:129)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2107)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:143)
at android.app.ActivityThread.main(ActivityThread.java:4701)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:521)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.IllegalArgumentException: provider==null
at android.location.LocationManager.requestLocationUpdates(LocationManager.java:625)
at polis.koll.WebPageLoader.getLocation(WebPageLoader.java:54)
at polis.koll.WebPageLoader.onCreate(WebPageLoader.java:70)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2701)

这是我的代码

    public class WebPageLoader extends Activity implements LocationListener{
    public static String Android_ID = null;
    final Activity activity = this;
    private Location mostRecentLocation;

    private void CheckEnableGPS(){
        String provider = Settings.Secure.getString(getContentResolver(),
          Settings.Secure.LOCATION_PROVIDERS_ALLOWED);
           if(!provider.equals("")){
               //GPS Enabled
               getLocation();
           }else{
            Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
               startActivity(intent);
           }

       }


private void getLocation() {
    String provider = Settings.Secure.getString(getContentResolver(),
          Settings.Secure.LOCATION_PROVIDERS_ALLOWED);
           if(!provider.equals("")){
    LocationManager locationManager =
      (LocationManager)getSystemService(Context.LOCATION_SERVICE);
    Criteria criteria = new Criteria();
    criteria.setAccuracy(Criteria.ACCURACY_FINE);
    String bestprovider = locationManager.getBestProvider(criteria,true);
    locationManager.requestLocationUpdates(bestprovider, 1, 500, this);     
    mostRecentLocation = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
         }else{
            Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
               startActivity(intent);
           }
  }

@Override
public void onCreate(Bundle savedInstanceState)
{
    //AdManager.setTestDevices( new String[] { AdManager.TEST_EMULATOR } );
    super.onCreate(savedInstanceState);
    this.getWindow().requestFeature(Window.FEATURE_PROGRESS);
    setContentView(R.layout.main);

    getLocation();
    Android_ID = Secure.getString(getContentResolver(), Secure.ANDROID_ID);


    WebView webView = (WebView) findViewById(R.id.webView);
    webView.getSettings().setJavaScriptEnabled(true);
    /** Allows JavaScript calls to access application resources **/
    webView.addJavascriptInterface(new JavaScriptInterface(), "android16");
    webView.setWebChromeClient(new WebChromeClient() {
        public void onProgressChanged(WebView view, int progress)
        {
            activity.setTitle("Letar poliskontroller");
            activity.setProgress(progress * 100);


            if(progress == 100)
                activity.setTitle(R.string.app_name);
        }
    });


    webView.setWebViewClient(new WebViewClient() {

        @Override
        public void onReceivedError(WebView view, int errorCode, String description, String failingUrl)
        {
            // Handle the error
        }


     // Testade att ta bort denna override för att få market länkar att fungera
     //   @Override
     //   public boolean shouldOverrideUrlLoading(WebView view, String url)
     //   {
     //       view.loadUrl(url);
     //       return true;
     //   }
    });

    if (Locale.getDefault().getLanguage().equals("sv")){
    //webView.loadUrl("file:///android_asset/android.html");
        webView.loadUrl("file:///android_asset/findgps_sv.html");
    }else{
    //webView.loadUrl("http://m.bryggplatsen.se/android/polis/index.php");
    //webView.loadUrl("file:///android_asset/android_en.html");
        webView.loadUrl("file:///android_asset/findgps_en.html");
    }



}
    /** Sets up the interface for getting access to Latitude and Longitude data from device
     **/




private class JavaScriptInterface {
    public double getLatitude(){
        return mostRecentLocation != null ? mostRecentLocation.getLatitude() : Double.NaN;
    }

    public double getLongitude(){
        return mostRecentLocation != null ? mostRecentLocation.getLongitude() : Double.NaN;
    }


    public String getAndroid_ID(){
        return Android_ID;
    }

     public void sharethisapp(){
     startActivity(Intent.createChooser(sharespotIntent(), "Share this warning"));
     }
  }


@Override
public void onLocationChanged(Location location) {
    // TODO Auto-generated method stub

    getLocation();
    //CheckEnableGPS();
}

@Override
public void onProviderDisabled(String provider) {
    // TODO Auto-generated method stub
    getLocation();
}

@Override
public void onProviderEnabled(String provider) {
    // TODO Auto-generated method stub
    getLocation();
}

@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
    // TODO Auto-generated method stub
    getLocation();
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    super.onCreateOptionsMenu(menu);
    MenuItem item = menu.add("Shut down");
    item.setIcon(R.drawable.exit);

    item = menu.add("Share");
    item.setIcon(R.drawable.m_share);

    item = menu.add("Fix GPS");
    item.setIcon(R.drawable.globe);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    if (item.getTitle() == "Shut down") {
        System.exit(0);
        finish();
    }
    if (item.getTitle() == "Fix GPS") {
        getLocation();
    }
    if (item.getTitle() == "Share") {
        if (Locale.getDefault().getLanguage().equals("sv")){
        startActivity(Intent.createChooser(shareIntent(), "Dela denna app"));
        }else{
        startActivity(Intent.createChooser(shareIntent(), "Share this app"));
        }
    }
    return true;
}

private Intent shareIntent() {
        Intent shareIntent = new Intent(android.content.Intent.ACTION_SEND);
        shareIntent.setType("text/plain");      
    if (Locale.getDefault().getLanguage().equals("sv")){
        shareIntent.putExtra(android.content.Intent.EXTRA_SUBJECT, "Testa denna android app...");
        return shareIntent.putExtra(android.content.Intent.EXTRA_TEXT, "index.php");
    }else{
        shareIntent.putExtra(android.content.Intent.EXTRA_SUBJECT, "Try this cool android app...");
        return shareIntent.putExtra(android.content.Intent.EXTRA_TEXT, "index_en.php");         
    }

}


private Intent sharespotIntent() {
    Intent sharespotIntent = new Intent(android.content.Intent.ACTION_SEND);
    sharespotIntent.setType("text/plain");      
if (Locale.getDefault().getLanguage().equals("sv")){
    sharespotIntent.putExtra(android.content.Intent.EXTRA_SUBJECT, " la just upp en ny varning i appen Polisradar");
    return sharespotIntent.putExtra(android.content.Intent.EXTRA_TEXT, "warn.php?lat=" + mostRecentLocation.getLatitude() + "&lng=" + mostRecentLocation.getLongitude() + "");
}else{
    sharespotIntent.putExtra(android.content.Intent.EXTRA_SUBJECT, " just added a new warning in the app Policeradar");
    return sharespotIntent.putExtra(android.content.Intent.EXTRA_TEXT, "warn_en.php?lat=" + mostRecentLocation.getLatitude() + "&lng=" + mostRecentLocation.getLongitude() + "");       
    }
}

Answer 1

如果请求的名称不在数据库中，方法 Settings.Secure.getString() 可以返回 null。不过，我不知道为什么找不到 Settings.Secure.LOCATION_PROVIDERS_ALLOWED。但是，您的代码在检查提供程序是否为空字符串之前不会检查(在 getLocation() 中)提供程序是否为空。我认为这是你的第二个异常(exception)的来源。

框架深处看似随机的错误也可能是由于尝试在不支持您的代码中的某些内容的操作系统版本上运行您的应用程序而引起的。确保您的代码根据您在 list 中设置的 minSdkVersion 进行编译，而不仅仅是 targetSdkVersion。