How can I convert my QT/QML sample application to Android application (.apk) ?
There are a few places that you can obtain the APK. The easiest thing to do is to just press play in Qt Creator, and it will build the libraries, create and bundle the APK, push it to the device, and install it all in one go. You can then obtain the APK from the shadow build folder (the folder that is created next to the project folder during the build process). Inside of that, there is an android-build/bin folder, and you will see the APK there. You can then take this an install this on other devices.
If you are looking for a more official and less hacky type of way to build the APK (perhaps you need to do an automated daily build, or you have different options you want to specify/sign the APK), then you should use the "androiddeployqt" executable that is in your ~/Qt/5.4/android_armv7/bin folder. This takes a bit more time to get it set up (compared to just pressing play), but is a good resource if you are looking to have a build system set up in your organization. Note that Qt Creator just calls this tool for you when you press play. Please refer to the Qt documentation for more details - Deploying an Application on Android | Qt 5.4
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