單擊時更改自定義通知中圖像按鈕的背景顏色

Question

我有一個包含四個圖像按鈕的自定義通知布局。

用戶單擊它們時，我需要更改圖像按鈕的背景顏色。

我需要用

ImageButton imgButton = (ImageButton) findViewById(R.id.recentAppButt);
imgButton.setBackgroundColor(Color.BLUE);

但這會引起nullpointerexception錯誤，因為編譯器找不到自定義通知布局中的最近使用的圖像按鈕，因為這些圖像按鈕在自定義通知布局中。

這是來自mainActivity.class的一些代碼，我在其中創建或刪除通知

private void createNotificationIcons() {
    String ns = Context.NOTIFICATION_SERVICE;
    notificationManager = (NotificationManager) getSystemService(ns);

    notification = new NotificationCompat.Builder(this)
            .setSmallIcon(R.drawable.home)
            .setContentTitle("My notification")
            .setContentText("All Buttons!")
            .setOngoing(true) /** notification will appear as ongoing notification*/
            .build();                      
    /** set a custom layout to the notification in notification drawer  */
    RemoteViews notificationView = new RemoteViews(getPackageName(), R.layout.notification);
    notification.contentView = notificationView;

    Intent recentAppIntent = new Intent(Context.NOTIFICATION_SERVICE);
    recentAppIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    Bundle recentAppBundle = new Bundle();   
    recentAppBundle.putInt("userAnswer", 1);
    recentAppIntent.putExtras(recentAppBundle);
    PendingIntent pendingrecentAppIntent = PendingIntent.getBroadcast(getBaseContext(), 1, recentAppIntent, 0);
    notificationView.setOnClickPendingIntent(R.id.recentAppButt, pendingrecentAppIntent);

    notificationManager.notify(1, notification);
}


public class SwitchButtonListener extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        Bundle answerBundle = intent.getExtras();
        int userAnswer = answerBundle.getInt("userAnswer");
        if(userAnswer == 1) {
            ImageButton imgButton = (ImageButton) findViewById(R.id.recentAppButt);
            imgButton.setBackgroundColor(Color.BLUE);
            Toast.makeText(context, "Recent Apps", Toast.LENGTH_SHORT).show();
            Log.d("Recent", "recent app butt clicked");
            openRecentApps();
        }
    }
}

public class BackgroundService extends Service {

    MainActivity mainActivity = new MainActivity();
    MainActivity.SwitchButtonListener switchButtonListener = mainActivity.new   SwitchButtonListener();

    /** Called when the service is being created. */
    @Override
    public void onCreate() {
        super.onCreate();
    }

    /** The service is starting, due to a call to startService() */
    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        registerReceiver(switchButtonListener, new     IntentFilter(Context.NOTIFICATION_SERVICE));
    return START_STICKY;
}

    /** Called when The service is no longer used and is being destroyed */
    @Override
    public void onDestroy() {
        super.onDestroy();
        unregisterReceiver(switchButtonListener);
    }

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

這是notification.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
style="@android:style/TextAppearance.StatusBar.EventContent"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@android:color/transparent" >

<!-- create home button in notification drawer -->

<ImageButton
    android:id="@+id/homeButt"
    android:layout_width="79dp"
    android:layout_height="79dp"
    android:layout_marginLeft="1dp"
    android:background="@android:color/transparent"
    android:contentDescription="@string/discription"
    android:src="@drawable/home" />

<!-- create recent apps button in notification drawer -->

<ImageButton
    android:id="@+id/recentAppButt"
    android:layout_width="79dp"
    android:layout_height="79dp"
    android:background="@android:color/transparent"
    android:contentDescription="@string/discription"
    android:src="@drawable/recent" />

<!-- create lock screen button in notification drawer -->

<ImageButton
    android:id="@+id/lockScreenButt"
    android:layout_width="79dp"
    android:layout_height="79dp"
    android:background="@android:color/transparent"
    android:contentDescription="@string/discription"
    android:src="@drawable/lock" />

<!-- create allButtons button in notification drawer -->

<ImageButton
    android:id="@+id/allButtonsButt"
    android:layout_width="79dp"
    android:layout_height="79dp"
    android:background="#FF990000"
    android:contentDescription="@string/discription"
    android:src="@drawable/all_buttons" />

提前致謝。

Answer 1

檢查布局文件中的ImageView是否具有將height和width的參數設置為wrap_parent 。

如果其中任何一個（layout_height或layout_width）設置為wrap_content ，並且您在ImageView上沒有設置實際圖像，則將其高度設置為0。換句話說，您應該將wrap_content更改為另一個值，例如以100dp為例，看看顏色是否改變。

Answer 2

findViewById是Activity類的一種方法，不適用於RemoteViews和通知。 您收到空值異常，因為R.id.recentAppButt在您的活動視圖中不存在。

您可以通過在drawables文件夾中創建兩個具有不同背景顏色的圖標來實現所需的功能。 然后，可以使用RemoteViews類的setImageViewResource方法在兩個圖標之間切換，如下所示

notificationView.setImageViewResource(R.id.recentAppButt, R.drawable.icon_with_blue_background)

然后，您需要重建通知並通過NotificationManager重新通知 ，以便更新背景色。