title: Qt errors while building for android
body: <p>when I try to build my project in Qt creator for android, these errors occur:</p>
  
  <pre><code>Warning: QML import could not be resolved in any of the import paths: Qt.Class
  Warning: QML import could not be resolved in any of the import paths: QtQuick.Extras.Private.CppUtils
  Warning: QML import could not be resolved in any of the import paths: QtQuick.Extras.Private.CppUtils
  Warning: QML import could not be resolved in any of the import paths: QtQuick.Controls.Material.impl
  Warning: QML import could not be resolved in any of the import paths: QtQuick.Controls.impl
  Warning: QML import could not be resolved in any of the import paths: QtQuick.Controls.Universal.impl
  
  FAILURE: Build failed with an exception.
  </code></pre>
  
  <p>this is my <code>.pro</code> file content:</p>
  
  <pre><code>QT += qml quick
  
  CONFIG += c++11
  
  SOURCES += main.cpp \
      downloader.cpp \
      filemanager.cpp
  
  HEADERS += \
      downloader.h \
      filemanager.h
  
  RESOURCES += qml.qrc
  
  QT += network
  QT += xml
  QT += gui
  # Additional import path used to resolve QML modules in Qt Creator's code model
  QML_IMPORT_PATH = /home/muhammad/Qt5.9.0/5.9/android_armv7/qml/
  
  # Additional import path used to resolve QML modules just for Qt Quick Designer
  #QML_DESIGNER_IMPORT_PATH =
  
  # The following define makes your compiler emit warnings if you use
  # any feature of Qt which as been marked deprecated (the exact warnings
  # depend on your compiler). Please consult the documentation of the
  # deprecated API in order to know how to port your code away from it.
  DEFINES += QT_DEPRECATED_WARNINGS
  
  # You can also make your code fail to compile if you use deprecated APIs.
  # In order to do so, uncomment the following line.
  # You can also select to disable deprecated APIs only up to a certain version of Qt.
  #DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0
  
  # Default rules for deployment.
  qnx: target.path = /tmp/$${TARGET}/bin
  else: unix:!android: target.path = /opt/$${TARGET}/bin
  !isEmpty(target.path): INSTALLS += target
  
  DISTFILES += \
      android/AndroidManifest.xml \
      android/gradle/wrapper/gradle-wrapper.jar \
      android/gradlew \
      android/res/values/libs.xml \
      android/build.gradle \
      android/gradle/wrapper/gradle-wrapper.properties \
      android/gradlew.bat \
      android/AndroidManifest.xml \
      android/gradle/wrapper/gradle-wrapper.jar \
      android/gradlew \
      android/res/values/libs.xml \
      android/build.gradle \
      android/gradle/wrapper/gradle-wrapper.properties \
      android/gradlew.bat
  
  ANDROID_PACKAGE_SOURCE_DIR = $$PWD/android
  </code></pre>
  
  <p>how can I solve it?</p>