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I am trying to make a flash light widget for the galaxy nexus and have been stuck on this problem FOR DAYS. I have a widget that consists of a button that functions like a toggle. But I can't get the button to turn on the flash. The widget works as a toggle using toasts, but once I add the lines of code that communicate with the flash it crashes. So if you only left the toast code in each if statement, then the toasts would work. I know I am supposed to be using SurfaceHolder.Callback but I dont know how to implement that on a class that extends AppWidgetProvider. If someone could please look over my code and try to help me make this widget I would be very grateful. I just don't know how to implement this with the appwidgetprovider class.

This error comes up only when I have: 

//TURN FLASH OFF
Parameters p = cam.getParameters();
p.setFlashMode(Parameters.FLASH_MODE_OFF);
cam.setParameters(p);
cam.stopPreview();

and:

//TURN FLASH ON
Parameters p = cam.getParameters();
p.setFlashMode(Parameters.FLASH_MODE_TORCH);                    
cam.setParameters(p);
cam.startPreview();

If I dont put these lines of code in, the widget runs with no errors and only displays the toasts. Meaning it accesses the onReceive() method.

I am using a galaxy nexus. 

public class FlashWidget extends AppWidgetProvider {

Camera cam;
RemoteViews view;
private static final String ACTION_WIDGET_RECEIVER = "Action";
private static boolean isLightOn = false;



 @Override
    public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {

        final int n = appWidgetIds.length;
        view = new RemoteViews(context.getPackageName(), R.layout.widget_lay);

        for (int i = 0; i < n; i++) {  
               int appWidgetId = appWidgetIds[i];  

               Intent intent = new Intent(context, FlashWidget.class);
               intent.setAction(ACTION_WIDGET_RECEIVER);

               PendingIntent pend = PendingIntent.getBroadcast(context, 0, intent, 0);

               view.setOnClickPendingIntent(R.id.button1, pend);


               appWidgetManager.updateAppWidget(appWidgetId, view);
        }


    }

    @Override
    public void onReceive(Context context, Intent intent) {

        String action =intent.getAction();

        if(intent.getAction().equals(action)) {


            //YES ITS ON, so turn it OFF
            if(isLightOn) {

                isLightOn = false;
                //TURN FLASH OFF
                Parameters p = cam.getParameters();
                p.setFlashMode(Parameters.FLASH_MODE_OFF);
                cam.setParameters(p);
                cam.stopPreview();
                Toast.makeText(context, "Flash OFF", Toast.LENGTH_SHORT).show();

            //NO ITS OFF, SO LETS TURN IT ON
            } else {

                isLightOn = true;
                //TURN FLASH ON
                Parameters p = cam.getParameters();
                p.setFlashMode(Parameters.FLASH_MODE_TORCH);

                cam.setParameters(p);
                cam.startPreview();
                Toast.makeText(context, "Flash ON", Toast.LENGTH_SHORT).show();

            }

            super.onReceive(context, intent);

        }


    } 
}

AndroidManifest.xml

<uses-sdk
android:minSdkVersion="14"
android:targetSdkVersion="17" />

<uses-permission android:name="android.permission.CAMERA"/>
<uses-feature android:name="android.hardware.camera"/>



<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name="com.example.flash.MainActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

    <receiver 
        android:name=".FlashWidget"
        android:label="Flash">
        <intent-filter>
            <action android:name="android.appwidget.action.APPWIDGET_UPDATE"/>
            <action android:name="com.example.flash.ACTION_WIDGET_RECEIVER"/>
            <action android:name="android.appwidget.action.APPWIDGET_ENABLED"/>
        </intent-filter>
        <meta-data 
            android:name="android.appwidget.provider"
            android:resource="@xml/widget_in"/>
   </receiver>
</application>

</manifest>

And this is the error I get when I try to put the widget on my home screen

E/AndroidRuntime(10346): FATAL EXCEPTION: main
E/AndroidRuntime(10346): java.lang.RuntimeException: Unable to start receiver com.example.flash.FlashWidget: java.lang.NullPointerException
at android.app.ActivityThread.handleReceiver(ActivityThread.java:2236)
E/AndroidRuntime(10346): at android.app.ActivityThread.access$1500(ActivityThread.java:130)
E/AndroidRuntime(10346): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1271)
4

3 に答える 3

0

manifest.xml ファイルにいくつかの条件を入れる必要があります

<receiver
        android:name=".FlashWidget "
        android:label="FlashLight">
        <intent-filter>
            <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
        </intent-filter>            
        <meta-data
            android:name="android.appwidget.provider"
            android:resource="@xml/your xml file" />
    </receiver>

何か問題がありましたら、お知らせください。

于 2013-03-12T04:34:04.597 に答える