The error is not from your CMake syntax. It is because your project is being built with Qt 5 or with an old Qt 6 kit. QNativeInterface is a Qt 6 header, and the Android API you probably want, QNativeInterface::QAndroidApplication, is available since Qt 6.2. Qt documents QNativeInterface as #include <QNativeInterface> since Qt 6.0, and QAndroidApplication::context() since Qt 6.2. (Qt Documentation)

Your CMake currently allows both Qt 6 and Qt 5:

cmake
find_package(QT NAMES Qt6 Qt5 REQUIRED COMPONENTS Widgets)
find_package(Qt${QT_VERSION_MAJOR} REQUIRED COMPONENTS Widgets)

So if Qt Creator is using a Qt 5 kit, CMake happily configures Qt 5, then this fails:

cpp
#include <QNativeInterface>

Recommended fix: require Qt 6.2+

Change the top Qt part of your CMake to this:

cmake
find_package(Qt6 6.2 REQUIRED COMPONENTS Core Widgets)

and link Core explicitly:

cmake
target_link_libraries(Admob PRIVATE Qt6::Core Qt6::Widgets)

So your cleaned-up CMake should look like this:

cmake
cmake_minimum_required(VERSION 3.16)

project(Admob VERSION 0.1 LANGUAGES CXX)

set(CMAKE_AUTOUIC ON)
set(CMAKE_AUTOMOC ON)
set(CMAKE_AUTORCC ON)

set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

find_package(Qt6 6.2 REQUIRED COMPONENTS Core Widgets)

set(PROJECT_SOURCES
    main.cpp
    widget.cpp
    widget.h
    widget.ui
)

qt_add_executable(Admob
    MANUAL_FINALIZATION
    ${PROJECT_SOURCES}
)

target_link_libraries(Admob PRIVATE Qt6::Core Qt6::Widgets)

if(ANDROID)
    set_property(TARGET Admob PROPERTY
        QT_ANDROID_PACKAGE_SOURCE_DIR
        "${CMAKE_CURRENT_SOURCE_DIR}/android"
    )
endif()

set_target_properties(Admob PROPERTIES
    MACOSX_BUNDLE TRUE
    WIN32_EXECUTABLE TRUE
)

include(GNUInstallDirs)

install(TARGETS Admob
    BUNDLE DESTINATION .
    LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
    RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
)

qt_finalize_executable(Admob)

Also guard the Android-only code

In widget.cpp, do not include Android/Qt-native-interface headers unconditionally. Use this:

cpp
#include <QtGlobal>

#if defined(Q_OS_ANDROID)
#include <QJniObject>
#include <QNativeInterface>
#endif

Then any Android call should also be guarded:

cpp
#if defined(Q_OS_ANDROID)
QJniObject context = QNativeInterface::QAndroidApplication::context();

// Example:
QJniObject::callStaticMethod<void>(
    "com/your/package/AdMobBridge",
    "initialize",
    "(Landroid/content/Context;)V",
    context.object<jobject>()
);
#endif

QJniObject is the Qt 6 JNI wrapper used for calling Java from C++, and Qt’s Android examples use it together with QNativeInterface::QAndroidApplication::context(). (Qt Documentation)

Check your kit in Qt Creator

In Qt Creator, make sure you are building with something like:

text
Qt 6.2+ for Android

not:

text
Desktop Qt 5.x MinGW
Desktop Qt 6.x MinGW

or:

text
Android Qt 5.x

For this specific QNativeInterface::QAndroidApplication approach, use Qt 6.2 or newer for Android.

One more note about AdMobBridge.java

This line is probably not useful:

cmake
AdMobBridge.java

Java files for Android should usually live under your Android package source directory, for example:

text
android/src/com/your/package/AdMobBridge.java

Your CMake already points Qt to that Android folder with:

cmake
QT_ANDROID_PACKAGE_SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/android"

So remove AdMobBridge.java from qt_add_executable() and put it in the correct android/src/... Java package path.