1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
|
// Copyright (C) 2021 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only
/*!
\title Qt Android Notifier
\example platform/androidnotifier
\examplecategory {Mobile}
\brief Demonstrates calling Java code from Qt in an Android application.
\image androidnotifier.png
This example demonstrates how to add a custom Java class to an Android
application, and how to call it using the JNI convenience APIs in Qt.
Click on one of the smiley faces to send a notification in the status bar
of the Android screen.
\include examples-run.qdocinc
\section1 Calling Java Methods from C++ Code
We define a custom Java class called \c NotificationClient in the
NotificationClient.java file:
\quotefromfile platform/androidnotifier/android/src/org/qtproject/example/androidnotifier/NotificationClient.java
\skipto org.qtproject.example.androidnotifier
\printuntil /^\}/
In the NotificationClient C++ class header file, \c notificationclient.h, we
declare a simple C++ API to display notifications on an Android device. It
consists of a single string property, \c notification, and a slot,
\c updateAndroidNotification(), that calls the Java code:
\snippet platform/androidnotifier/notificationclient.h Qt Notification Class
We connect the \c notificationChanged() signal to the
\c updateAndroidNotification() slot to update the notification text when the
\c notification text changes:
\snippet platform/androidnotifier/notificationclient.cpp notification changed signal
The \c updateAndroidNotification() function calls the Java method responsible
for sending the notification from the Android platform APIs. First, we construct
a Java string \c jstring from the notification string, then pass the \c jstring
object as a parameter to the \c notify() method in Java:
\snippet platform/androidnotifier/notificationclient.cpp Send notification message to Java
The call to the Java meethod use \l QJniObject which relies on the Java Native
Interface (JNI) APIs to communicate with Java. Also, in the previous snippet,
we are passing the app's context object, which the static Java code can use
to tap into the app's specific properties and APIs.
To make sure our smiley buttons do what they are supposed to, we add the
the following code to change the notification text if either of them are
clicked:
\snippet platform/androidnotifier/main.cpp Connect button signals
\sa {Qt for Android}
*/
|
