android app runs popup window in the background

Implementation of pop-up windows running in the background of Android App

Android is a popular mobile operating system that supports multi-task concurrent operation. However, in some specific scenarios, we may want to pop up a pop-up window when the app is running in the background to remind users or display relevant information. This article will introduce how to pop up popups when Android App is running in the background, and provide corresponding code examples.

Understand the background operation mechanism

Before we start, we need to understand the background running mechanism of Android App. In order to save resources and improve system performance, the Android system will restrict the operation of the app in the background in some cases. When an app enters the background, the system will gradually reduce the priority of the app and restrict its resource usage to ensure the smooth operation of the foreground app.

Use Service to implement pop-up window

Android provides Service components for scenarios such as running long tasks in the background or playing music. We can use Service to realize the function of pop-up windows when the App is running in the background.

First, create a class inherited from Service to use for pop-up windows.

public class PopupService extends Service {
    private WindowManager windowManager;
    private View popupView;
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }
    @Override
    public void onCreate() {
        ();
        windowManager = (WindowManager) getSystemService(WINDOW_SERVICE);
        // Create a pop-up view here        popupView = (this).inflate(.popup_view, null);
        // Set the pop-up window position and other properties         params = new (
                .WRAP_CONTENT,
                .WRAP_CONTENT,
                .TYPE_APPLICATION_OVERLAY, // Support display on other apps                .FLAG_NOT_FOCUSABLE,
                );
         = ;
        (popupView, params);
    }
    @Override
    public void onDestroy() {
        ();
        if (popupView != null && windowManager != null) {
            (popupView);
        }
    }
}

In the above code, we use WindowManager to add and remove pop-up views. Note that we used TYPE_APPLICATION_OVERLAY to set the pop-up window to display above other apps, and set FLAG_NOT_FOCUSABLE to ensure that the pop-up window does not get focus.

Start Service in the onPause() method of Activity

Next, we need to start the Service when running in the background of the App. Start the Service in the onPause() method of the Activity and stop the Service in the onResume() method.

public class MainActivity extends AppCompatActivity {
    private Intent popupServiceIntent;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        (savedInstanceState);
        setContentView(.activity_main);
        popupServiceIntent = new Intent(this, );
    }
    @Override
    protected void onResume() {
        ();
        stopService(popupServiceIntent);
    }
    @Override
    protected void onPause() {
        ();
        startService(popupServiceIntent);
    }
}

In the above code, we start the Service through the startService() method and stop the Service through the stopService() method. In this way, when the App enters the background, the pop-up window will pop up; when the App re-enters the front desk, the pop-up window will automatically close.

Summarize

By using Service and WindowManager, we can pop up windows when the Android App is running in the background. This article provides corresponding code examples, hoping to help readers implement related functions.

In actual applications, we also need to pay attention to some security and user experience issues, such as the permission application of pop-up windows, the content and style design of pop-up windows, etc. At the same time, we also need to abide by the restrictions on the background operation of the Android system to ensure that the behavior of the app running pop-up windows in the background meets user expectations and system requirements.

appendix

Layout file popup_view.xml

<LinearLayout xmlns:andromatch_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:background="#FFFFFF"
    android:padding="16dp">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="This is a

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