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Using CrystaX with Qt to build android application: java.lang.UnsatisfiedLinkError

I am trying to build Qt application for android using Qt Creator. I use CrystaX NDK for android instead of goolge's one because I need to use boost libraries in my project, and, as CrystaX's official site says, it is comes with it.
I am using following versions of tools:
Qt Creator 3.4.2
Qt 5.5.0
CrystaX NDK 10.2.1
At first, I had to manually add libraries and headers paths in my .pro file, because it hasn't been found automatically. There was compiler error: can't locate libcrystax, there was some errors in source files about including boost headers. I've added following lines in my project file:
android {
INCLUDEPATH += $$NDK_ROOT/sources/crystax/include \
$$NDK_ROOT/sources/boost/1.58.0/include \
$$PWD/ssl
LIBS += -L"$$PWD/ssl" -lssl -lcrypto
LIBS += -L"$$NDK_ROOT/sources/crystax/libs/$$ANDROID_TARGET_ARCH"
ANDROID_EXTRA_LIBS = $$NDK_ROOT/sources/crystax/libs/$$ANDROID_TARGET_ARCH/libcrystax.so
ANDROID_PACKAGE_SOURCE_DIR = $$PWD/android
}
After rebuilding again, I've got an error (runtime error) that says libgnustl_shared requires libcrystax, but libcrystax is not loaded or something similar.
After searching the internet, I've found that it's happening because one library that requires another, is loading before it, and that second library, is not being searched for, at application directory, only in system paths.
I've found a workaround - to load required library manually. I copied default QtActivity.java into my project directory (android/src/.../QtActivity.java) to replace default one and added following code:
static {
System.loadLibrary( "crystax" );
}
After that I am not getting that error, but now I'm stuck with another one:
java.lang.UnsatisfiedLinkError: Cannot load library: reloc_library[1285]: 37 cannot locate '__aeabi_ldiv0'...
Is it possible to use Qt + CrystaX NDK for build android app? Am I doing it wrong way? Please, explain how to do it properly, if I've mistaken or if I misunderstood whole concept. Any help is appreciated.

This happens because you haven't linked with libgcc.a. I don't know how exactly your build system works (well, Qt's one), but generally, adding libgcc.a to the list of additional libraries should help:
ANDROID_EXTRA_LIBS = $$NDK_ROOT/toolchains/arm-linux-androideabi-4.9/prebuilt/darwin-x86_64/lib/gcc/arm-linux-androideabi/4.9/libgcc.a
This line specify arm variant of libgcc.a; obviously, you should use proper one depending on ANDROID_TARGET_ARCH value.

How Android executables are built?

I am trying to write a program for an executable which is similar to dumpsys. I have created a .cpp file and an Android.mk file. However, when I run ndk-build on either programs, I get compilation error. On the other hand, the same dumpsys program is built correctly when I compile the whole Android source.
The first error I get is
fatal error: utils/Log.h: No such file or directory. Then I have to use LOCAL_C_INCLUDES to solve this.
Next, I get undefined reference to methods errors like undefined reference to android::String16::String16().
After that, I link some objects like String16.o to solve this issue. But some of them depend on other objects and I have to add the one by one. I don't know how Android build compiles dumpsys without facing such issues.
How is ndk-build different from compiling the whole Android source? What is the right way to build if I want to compile a standalone project?

Building PCL for Android

Does anyone have instructions for building the Point Cloud Library (PCL) for Android? I found a few superbuilds of PCL that claim to be able to build PCL and its dependencies. I tried the superbuild from http://www.hirotakaster.com/weblog/how-to-build-pcl-for-android-memo/. I'm using Ubuntu 14.10, Android 19, NDK r10d, and PCL 1.6.0, but I'm willing to use any versions. I'm also using the terminal for compiling. For Android hardware, I'm using a Project Tango.
I tried using android-cmake (http://code.google.com/p/android-cmake/), but I'm not sure how to build the proper toolchain. I continually receive the error "Could not find any working toolchain in the NDK. Probably your Android NDK is broken." I get this error with plain cmake and ccmake, too.
Does anyone have any detailed instructions for building PCL for Android (e.g., a bash script or terminal instructions)? Or, does anyone have a link to pre-built libraries?

(Caveat Emptor: This is not a long term solution)
I was able to get past the CMAKE error by editing the cmake file
pcl-superbuild/toolchains/toolchain-android.cmake
These two changes should get past the errors mentioned above:
set( ANDROID_NDK_HOST_SYSTEM_NAME "linux-x86" ) # Line 468
Should be
set( ANDROID_NDK_HOST_SYSTEM_NAME "linux-x86_64" )
This will generate another error, unless you change the following line (Line 1023)
if( ANDROID_NDK_RELEASE STRGREATER "r8" ) # r8b
Should be
if( ANDROID_NDK_RELEASE STRGREATER "r10" ) # r8b
The first change adds _64 to x86_64. The second adds compatibility for r10d.
This doesn't fix all of the errors though, because BOOST threads don't place nicely with GCC 4.6+. Implement the patch shown at this link (https://svn.boost.org/trac/boost/ticket/6165).
Again, that still doesn't fix all of the errors. (I haven't figured out why this is needed yet, math.h shouldn't need std::). In the file,
pcl-superbuild/CMakeExternals/Source/pcl/common/include/pcl/pcl_macros.h
Edit lines 99-102:
# define pcl_isnan(x) isnan(x)
# define pcl_isfinite(x) isfinite(x)
# define pcl_isinf(x) isinf(x)
They should be:
# define pcl_isnan(x) std::isnan(x)
# define pcl_isfinite(x) std::isfinite(x)
# define pcl_isinf(x) std::isinf(x)
PCL still generates many warnings, but at least it compiles (so far)
**EDIT: **
This doesn't get you all the way (unfortunately) because the boost libraries don't play well with C++11.
To fix this, download boost 1.55 from http://sourceforge.net/projects/boost/files/boost/1.55.0/, and overwrite the boost directory
pcl-superbuild/CMakeExternals/Source/boost/boost_1_45_0
(This directory gets created when you run make for the first time).
Next, modify
pcl-superbuild/CMakeExternals/Source/boost/CMakeLists.txt
and find the line:
file(GLOB lib_srcs ${boost_root}/libs/filesystem/v2/src/*.cpp)
replace it with
file(GLOB lib_srcs ${boost_root}/libs/filesystem/src/*.cpp)
That's as far as I've gotten

this link helps a lot, you can take a look. I also left some comments there..
http://www.hirotakaster.com/weblog/how-to-build-pcl-for-android-memo/
for compile pcl 1.6 with ndk r10d, you need to replace toolchain-android.cmake with the toolchain from opencv library

I built PCL and its dependencies using Ubuntu 14.10, 32-bit. I also had to use NDK r8c, 32-bit. The key to building Hirotakaster's superbuild was using a 32-bit os.

I managed to compile your super build with Ubuntu 15.10 64-bit and NDK r10e. I changed the toolchain-android.cmake with the one from OpenCV. Then in common.hpp(found in /Source/pcl/common/include/pcl/common/impl) I had to add the following lines:
# include < math.h >
# define pcl_isnan(x) std::isnan(x)
# define pcl_isfinite(x) std::isfinite(x)
# define pcl_isinf(x) std::isinf(x)

libgdal.so android error: could not load library "libgdal.so.1"

My problem is the following: I have succesfully built GDAL 1.10.1 using an Android toolchain (CC=i686-linux-android-gcc, CXX=i686-linux-android-c++) that produces the following output libraries libgdal.a, libgdal.la, libgdal.lai, libgdal.so, libgdal.so.1, libgdal.so.1.17.1 in the output folder .libs (in the following I'll call this folder $GDAL_LIB_PATH).
I am trying to build a simple Android app (a simple widget application with a QPushButton named TestAndroid) using Qt 5.4 on Windows. If I don't use GDAL everything works fine and I am able to run my app on an Android emulator for all available platforms: x86, armeabi and armeabi-v7.
Nonetheless, if I try to use GDAL (ex. by simply calling GDALAllRegister() in the initialization of the app) and then linking to libgdal.so the application crashes with the following error:
E/art ( 1614):
dlopen("/data/app/org.qtproject.example.TestAndroid-1/lib/x86/libTestAndroid.so",
RTLD_LAZY) failed: dlopen failed: could not load library
"libgdal.so.1" needed by "libTestAndroid.so"; caused by library
"libgdal.so.1" not found
I have verified that the Android platform is the right one (x86), otherwise the linker would skip the wrong libgdal.so object.
I have included libgdal.so in the *.apk (generated by Qt) using ANDROID_EXTRA_LIBS *= $GDAL_LIB_PATH/libgdal.so. The other files libgdal.so.x.x cannot be included in the same way since Qt prevents it.
In order to avoid dynamic linking I have also tried to link my app with libgdal.a but many link-time errors appears (ex. undefined reference to 'atof')
I have searched on the web but I have not found a solution to my problem.
I am not constrained to use dynamic linking so, a solution to any of the following problems is good for me:
Is there a way to avoid the creation of libgdal.so.x.x files when building GDAL ?
Is there a way to include libgdal.so.x.x files in the *.apk file generated by Qt ?
How can I avoid link-time errors when linking the static library libgdal.a ?
Thanks in advance for any reply!

After several days of trials and errors (mainly errors) I have found a solution to my problem.
I'm writing it as an answer to my question so that it may be helpful to others.
The problem was during the link-time of GDAL. Briefly: the linker created the "real name" shared library libgdal.so.1.17.1 together with the links to it libgdal.so.1 and libgdal.so.
For some reasons (which I ignore) forcing the link to libgdal.so, the linker searches for libgdal.so.1 (which, in turn, would have searched for libgdal.so.1.17.1).
The workaround that solved my problem can be summarized in the following steps:
In the GDAL root, run the ./configure according to the desired configuration (see http://trac.osgeo.org/gdal/wiki/BuildingForAndroid) checking that libtool is ENABLED
Edit the created libtool file (e. g. with gedit) as follows:
replace the value of library_names_spec with library_names_spec="\$libname\${shared_ext}"
replace the value of soname_spec with soname_spec=""
Type make
In the output folder .libs/ the only libgdal.so will be created and now the link to libgdal.so seems to work fine.

STLport and Android NDK - STLport loaded as static, Linux/gcc ld reports "multiple definitions"

I've looked thru a lot of material on Android NDK and STLport. I have complex app, java+native code, which loads STLport (a c++ standard library port). The original codebase had "APP_STL := stlport_static" in the Application.mk in the project's "jni" subdir. Causes ld to load the lib static. This caused many compile failures, in current SDK/NDK.
Tried to load as a dynamic lib, as per a suggestion. (In "../jni/Application.mk", set "APP_STL := stlport_shared") With this, I get a clean compile, and load, and the app runs flawlessly on the Android armeabi-v7a emulator, if I disable checkJNI on the "dalvik" virtual machine.
But once I enable checkJNI, I get an "unsatisfiedLinkError" on the libapplication.so, which looks like it might result from STLport being dynamically loaded. So, I want to load STLport in static mode (logcat reports this after several other libs successfully loaded). During the build, compile is ok, but I am getting two multiple definition errors, specifically: "multiple definition of 'vtable for std::bad_exception' " and of 'std::exception::~exception()'. (I have also tried using "gnustl_static").
I am using gcc version 4.3.0 and make version 3.81, command line mode, and small wrapper around build-ndk, for android ndk-r9c, with a build target version of android-8, "ant" to build the .apk file, and so on.
Someone who has more familiarity with Android than me (I am a complete noob) might have seen this before. If so, please advise. Thanx. - Rus

It's definitely possible to use stlport_static with NDK r9c. What object files are mentioned with multiple definition errors? Maybe, you are using some prebuilt libraries? Maybe, the gcc version 4.3 is problematic? Why don't you use the default (gcc 4.8)?
With that, the NDK document explicitly encourages use of shared STL, but you must not forget to call System.loadLibrary() in correct order:
System.loadLibrary("stlport_shared");
System.loadLibrary("Rusfuture");