Develop Reference

CMake could not find JNI

I created a new Android Studio Project with C++ support and did not add anything to it. The project builds, compiles and runs with CMake. I then added the following two lines of code to CMakeLists.txt at the bottom of the file and I get a CMake build error.
find_package(Java COMPONENTS Development) # Line 47
find_package(JNI REQUIRED) # Line 48
And this is the error I get when building the project
-- Found Java: /usr/lib/jvm/java-10-oracle/bin/java (found version "10.0.1") found components: Development
-- Configuring incomplete, errors occurred!
CMake Error at /home/xxxxx/Android/Sdk/cmake/3.6.4111459/share/cmake-3.6/Modules/FindPackageHandleStandardArgs.cmake:148 (message):
Could NOT find JNI (missing: JAVA_AWT_LIBRARY JAVA_JVM_LIBRARY
See also "/home/xxxxx/AndroidStudioProjects/MyApplication/app/.externalNativeBuild/cmake/release/x86_64/CMakeFiles/CMakeOutput.log".
JAVA_INCLUDE_PATH2 JAVA_AWT_INCLUDE_PATH)
Call Stack (most recent call first):
/home/xxxxxx/Android/Sdk/cmake/3.6.4111459/share/cmake-3.6/Modules/FindPackageHandleStandardArgs.cmake:388 (_FPHSA_FAILURE_MESSAGE)
/home/xxxxxx/Android/Sdk/cmake/3.6.4111459/share/cmake-3.6/Modules/FindJNI.cmake:314 (FIND_PACKAGE_HANDLE_STANDARD_ARGS)
CMakeLists.txt:48 (find_package)
External native generate JSON release: JSON generation completed with problems
CMake runs when being called form the command line, but fails inside Android Studio for some reason and I am not sure why.
EDIT 1
Here is the CMakeOutput.log file
EDIT 2
This is all that is in CMakeLists.txt file. It compiles in cmd with the command cmake.
cmake_minimum_required(VERSION 3.4.1)
find_package(Java COMPONENTS Development)
find_package(JNI REQUIRED)
This is the cmd output
E:\Users\xxxxx\AndroidStudioProjects\MyApplication\app\build>cmake ..
-- Configuring done
-- Generating done
-- Build files have been written to: E:/Users/xxxxx/AndroidStudioProjects/MyApplication/app/build
When I try to add it compile it in Android Studio using gradle I get the following error on Windows 10 pro 64 bit
Microsoft Windows [Version 10.0.17134.112]
(c) 2018 Microsoft Corporation. All rights reserved.
E:\Users\xxxxx\AndroidStudioProjects\MyApplication>gradlew build --stacktrace
> Task :app:generateJsonModelDebug
External native generate JSON debug: starting JSON generation
External native generate JSON debug: using platform version 24 for ABI ARMEABI_V7A and min SDK version 24
External native generate JSON debug: noticing that build file 'E:\Users\xxxxx\AndroidStudioProjects\MyApplication\app\CMakeLists.txt' is out of date with respect to E:\Users\xxxxx\AndroidStudioProjects\MyApplication\app\.extern
alNativeBuild\cmake\debug\armeabi-v7a\android_gradle_build.json
External native generate JSON debug: rebuilding JSON E:\Users\xxxxx\AndroidStudioProjects\MyApplication\app\.externalNativeBuild\cmake\debug\armeabi-v7a\android_gradle_build.json due to:
External native generate JSON debug: - a dependent build file changed
External native generate JSON debug: keeping json folder 'E:\Users\xxxxx\AndroidStudioProjects\MyApplication\app\.externalNativeBuild\cmake\debug\armeabi-v7a' but regenerating project
External native generate JSON debug: executing cmake Executable : E:\Android\SDK\cmake\3.6.4111459\bin\cmake.exe
arguments :
-HE:\Users\xxxxx\AndroidStudioProjects\MyApplication\app
-BE:\Users\xxxxx\AndroidStudioProjects\MyApplication\app\.externalNativeBuild\cmake\debug\armeabi-v7a
-DANDROID_ABI=armeabi-v7a
-DANDROID_PLATFORM=android-24
-DCMAKE_LIBRARY_OUTPUT_DIRECTORY=E:\Users\xxxxx\AndroidStudioProjects\MyApplication\app\build\intermediates\cmake\debug\obj\armeabi-v7a
-DCMAKE_BUILD_TYPE=Debug
-DANDROID_NDK=E:\Android\SDK\ndk-bundle
-DCMAKE_CXX_FLAGS=
-DCMAKE_TOOLCHAIN_FILE=E:\Android\SDK\ndk-bundle\build\cmake\android.toolchain.cmake
-DCMAKE_MAKE_PROGRAM=E:\Android\SDK\cmake\3.6.4111459\bin\ninja.exe
-GAndroid Gradle - Ninja
jvmArgs :
CMake Error at E:/Android/SDK/cmake/3.6.4111459/share/cmake-3.6/Modules/FindPackageHandleStandardArgs.cmake:148 (message):
Could NOT find JNI (missing: JAVA_AWT_LIBRARY JAVA_JVM_LIBRARY
JAVA_INCLUDE_PATH2 JAVA_AWT_INCLUDE_PATH)
Call Stack (most recent call first):
E:/Android/SDK/cmake/3.6.4111459/share/cmake-3.6/Modules/FindPackageHandleStandardArgs.cmake:388 (_FPHSA_FAILURE_MESSAGE)
E:/Android/SDK/cmake/3.6.4111459/share/cmake-3.6/Modules/FindJNI.cmake:314 (FIND_PACKAGE_HANDLE_STANDARD_ARGS)
CMakeLists.txt:4 (find_package)
-- Configuring incomplete, errors occurred!
See also "E:/Users/xxxxx/AndroidStudioProjects/MyApplication/app/.externalNativeBuild/cmake/debug/armeabi-v7a/CMakeFiles/CMakeOutput.log".

Could NOT find JNI (missing: JAVA_AWT_LIBRARY JAVA_JVM_LIBRARY
Solved with
sudo apt-get install -y openjdk-8-jdk
sudo apt-get install -y default-jdk
export JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64

As the CMake version bundled with Android tries to tell you, it can't find the JNI package because some parts were missing:
missing: JAVA_AWT_LIBRARY JAVA_JVM_LIBRARY JAVA_INCLUDE_PATH2 JAVA_AWT_INCLUDE_PATH
Checking the documentation for FindJNI (https://cmake.org/cmake/help/latest/module/FindJNI.html) these variables are set to the locations of libraries and headers not shipped with the Android version of JNI (to little surprise, Android does not included the AWT library for instance).
When running find_package(JNI REQUIRED), the FindJNI code checks if these variables are set and if not, issues an error.
A workaround is to set these variables yourself, before calling find_package:
# We are only interested in finding jni.h: we do not care about extended JVM
# functionality or the AWT library.
set(JAVA_AWT_LIBRARY NotNeeded)
set(JAVA_JVM_LIBRARY NotNeeded)
set(JAVA_INCLUDE_PATH2 NotNeeded)
set(JAVA_AWT_INCLUDE_PATH NotNeeded)
find_package(JNI REQUIRED)
Be aware though, that your code will only be able to use jni.h and its functionality: if it tries to access any other part of the JNI package it will fail (probably at compile time) because essentially, you have tricked CMake into thinking that the entire package was found, when in reality only a part of it exists in the Android setup.

I found a solution that works for me:
cmake_minimum_required(VERSION 3.10)
project("ktaglib")
set(JAVA_AWT_LIBRARY "$ENV{JAVA_HOME}/lib/libjawt.so")
set(JAVA_JVM_LIBRARY "$ENV{JAVA_HOME}/lib/server/libjvm.so")
set(JAVA_INCLUDE_PATH "$ENV{JAVA_HOME}/include")
set(JAVA_INCLUDE_PATH2 "$ENV{JAVA_HOME}/include/linux")
set(JAVA_AWT_INCLUDE_PATH "$ENV{JAVA_HOME}/include")
find_package(JNI REQUIRED)
You must set the environment variable JAVA_HOME="/usr/lib/jvm/java-11-openjdk-amd64" beforehand.
More info: https://github.com/dockcross/dockcross/issues/576

Same on alpine:edge docker image, fixed using:
ENV JAVA_HOME=/usr/lib/jvm/java-1.8-openjdk
RUN apk add --no-cache openjdk8
ref: https://pkgs.alpinelinux.org/contents?branch=edge&name=openjdk8&arch=x86_64&repo=community

Building phone gap app for Android failing

When trying to build my phone gap app for android using
sudo phonegap build android
it fails with this error:
:compileDebugJava
/Users/youssefsami/Library/Mobile Documents/com~apple~CloudDocs/Developer/Mobile Apps/UzuConvert/platforms/android/src/org/apache/cordova/inappbrowser/InAppBrowser.java:120: error: cannot find symbol
|| Config.isUrlWhiteListed(url)) {
^
symbol: method isUrlWhiteListed(String)
location: class Config
Note: Some input files use or override a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
1 error
FAILED
FAILURE:
Build failed with an exception.
* What went wrong:
Execution failed for task ':compileDebugJava'.
>
Compilation failed; see the compiler error output for details.
* Try:
Run with
--stacktrace option to get the stack trace. Run with
--info or
--debug
option to get more log output.
BUILD FAILED
Total time: 5.607 secs
/Users/youssefsami/Library/Mobile Documents/com~apple~CloudDocs/Developer/Mobile Apps/UzuConvert/platforms/android/cordova/node_modules/q/q.js:126
throw e;
^
Error code 1 for command: /Users/youssefsami/Library/Mobile Documents/com~apple~CloudDocs/Developer/Mobile Apps/UzuConvert/platforms/android/gradlew with args: cdvBuildDebug,-b,/Users/youssefsami/Library/Mobile Documents/com~apple~CloudDocs/Developer/Mobile Apps/UzuConvert/platforms/android/build.gradle,-Dorg.gradle.daemon=true
ERROR building one of the platforms: Error: /Users/youssefsami/Library/Mobile Documents/com~apple~CloudDocs/Developer/Mobile Apps/UzuConvert/platforms/android/cordova/build: Command failed with exit code 1
You may not have the required environment or OS to build this project
Error: /Users/youssefsami/Library/Mobile Documents/com~apple~CloudDocs/Developer/Mobile Apps/UzuConvert/platforms/android/cordova/build: Command failed with exit code 1
at ChildProcess.whenDone (/usr/local/lib/node_modules/phonegap/node_modules/cordova/node_modules/cordova-lib/src/cordova/superspawn.js:131:23)
at ChildProcess.emit (events.js:110:17)
at maybeClose (child_process.js:1015:16)
at Process.ChildProcess._handle.onexit (child_process.js:1087:5)
I tried setting the java_home to the java alias in lib exec but still nothing. Any ideas on what maybe causing the problem?

It's because your InAppBrowser plugin is out date and probably out of sync with a newer version of the Cordova Android platform than when you first installed the plugin. I was getting the same issue with cordova-android#4.0.0 and 0.5.3 of InAppBrowser.
Fix is to first remove plugin
cordova plugin rm org.apache.cordova.inappbrowser
Then add it again (it should reinstall with the latest version the cordova CLI has in my case it grabbed 0.6). You can check the version in the RELEASENOTES.md in the plugins/org.apache.cordova.inappbrowser/ folder.
cordova plugin add org.apache.cordova.inappbrowser
You will need to remove the android platform and re-add it before building again so it doesn't keep the old version of the plugin.
cordova platform rm android
and
cordova platform add android
Now build again and the error should have gone.
EDIT: I just noticed at the top of your question you are using phonegap. Since you tagged with cordova (and thats what I use) I answered with cordova commands, but I'm guessing almost the same process applies with Phonegap.

Same problem with cordova-android#4.0.0
Thank's JDawgg your solution's better than mine, but if someone still have the bug you can use cordova-android#3.6.4 like this :
cordova platform remove android
then
cordova platform add android#3.6.4
you must have android 4.2.2 sdk installed
Finally
sudo phonegap build android

In case someone is using Meteor and came across the same problem, martijnwalraven suggests removing the older version of cordova-plugin-inappbrowser and add the most recent one:
$ meteor remove cordova:cordova-plugin-inappbrowser
$ meteor add cordova:cordova-plugin-inappbrowser#1.0.1
This did the trick for me!

Can't build cordova projects

I have a problem with setting up the work environment for Cordova on Windows 7 for Android. I use NetBeans 8 and followed this guide: Link Here
New project -> Cordova -> Hello World Template.
Whenever I try to build a Cordova project (in NetBeans) I get this message:
BUILD FAILED
C:\Users\Administrator\Documents\NetBeansProjects\HTML5Application2\platforms\android\build.xml:90: Cannot find C:\Users\Administrator\SkyDrive\Skolegang\Dataingeniør\Android\adt-bundle-windows-x86_64-20130729\sdk\tools\ant\build.xml imported from C:\Users\Administrator\Documents\NetBeansProjects\HTML5Application2\platforms\android\build.xml
Total time: 0 seconds
C:\Users\Administrator\Documents\NetBeansProjects\HTML5Application2\platforms\android\cordova\node_modules\q\q.js:126
throw e;
Error code 1 for command: cmd with args: /s,/c,ant,debug,-f,C:\Users\Administrator\Documents\NetBeansProjects\HTML5Application2\platforms\android\build.xml,-Dout.dir=ant-build,-Dgen.absolute.dir=ant-gen
Error: C:\Users\Administrator\Documents\NetBeansProjects\HTML5Application2\platforms\android\cordova\run.bat: Command failed with exit code 8
at ChildProcess.whenDone (C:\Users\Administrator\AppData\Roaming\npm\node_modules\cordova\node_modules\cordova-lib\src\cordova\superspawn.js:131:23)
at ChildProcess.EventEmitter.emit (events.js:98:17)
at maybeClose (child_process.js:743:16)
at Process.ChildProcess._handle.onexit (child_process.js:810:5)
Command finished with error code 8: C:\Users\Administrator\Documents\NetBeansProjects\HTML5Application2\platforms\android\cordova\run.bat --emulator
C:\Users\Administrator\Documents\NetBeansProjects\HTML5Application2\nbproject\build.xml:272: exec returned: 1
BUILD FAILED (total time: 47 seconds)
I have googled it for hours but can't seem to find a solution. Some people get some of the same errors(not exact, but similar), but the solutions did not work for me. One issue was regarding Java 8 and ant versions beneath 1.9.0 (I use Node 0.10.26, java 1.7.0_25, cordova 3.5.0-0.2.4 and ant 1.9.4). I also tried to create a new project with the console (CMD), but it gives the exact same error when I build. It's no problem to create the project, nor adding Android as a platform, the problem is building the project. I think the environment variables are set correctly since the java, node, ant and cordova commands work fine in cmd/powershell, and the check_reqs.bat said that the environment was fine.
It's this line that creates the error: <import file="${sdk.dir}/tools/ant/build.xml" />. This is the rest of the message: Cannot find C:\Users\Administrator\SkyDrive\Skolegang\Dataingeniør\Android\adt-bundle-windows-x86_64-20130729\sdk\tools\ant\build.xml imported from C:\Users\Administrator\Documents\NetBeansProjects\HTML5Application2\platforms\android\build.xml.
Here is the error I get in the command window (not using NetBeans):
PS C:\Users\Administrator\Desktop\test\fakeApp> cordova build android
Running command: C:\Users\Administrator\Desktop\test\fakeApp\platforms\android\cordova\build.bat
Buildfile: C:\Users\Administrator\Desktop\test\fakeApp\platforms\android\build.xml
BUILD FAILED
C:\Users\Administrator\Desktop\test\fakeApp\platforms\android\build.xml:90: Cannot find C:\Users\Administrator\SkyDrive\
Skolegang\Dataingeni├©r\Android\adt-bundle-windows-x86_64-20130729\sdk\tools\ant\build.xml imported from C:\Users\Admini
strator\Desktop\test\fakeApp\platforms\android\build.xml
Total time: 0 seconds
Error code 1 for command: cmd with args: /s,/c,ant,debug,-f,C:\Users\Administrator\Desktop\test\fakeApp\platforms\androi
d\build.xml,-Dout.dir=ant-build,-Dgen.absolute.dir=ant-gen
Error: C:\Users\Administrator\Desktop\test\fakeApp\platforms\android\cordova\build.bat: Command failed with exit code 2
at ChildProcess.whenDone (C:\Users\Administrator\AppData\Roaming\npm\node_modules\cordova\node_modules\cordova-lib\s
rc\cordova\superspawn.js:131:23)
at ChildProcess.EventEmitter.emit (events.js:98:17)
at maybeClose (child_process.js:743:16)
at Process.ChildProcess._handle.onexit (child_process.js:810:5)
I thought maybe it was a path issue since I have a special letter in the path were the NetBeansProjects are stored (and it's pretty long too), but creating a test directory at C:\ and creating the project with the command window gave the same error. I'm new at Cordova so I'm sure there's an easy solution, thanks in advance.

I solved it, though I tried to create a cordova project outside the OneDrive folder I did not think of the SDK path (which also were stored in OneDrive). By moving the SDK files to C: (the path could probably not contain the special letter 'ø') and changing the path of the environment variables (and the SDK path in NetBeans) it now runs perfectly.

Compiling Android JNI for OpenCV on Mac OSX

Bear with me - this is a long description, but I wanted to include all details. I'm trying use android NDK and JNI for building OpenCV Android apps.
I'm following this tutorial to get everything installed:
http://www.stanford.edu/class/ee368/Android/Tutorial-2-OpenCV-for-Android-Setup-Macintosh-API8.pdf
The following installed just fine:
/usr/bin/g++
/usr/local/bin/swig
/usr/bin/cmake
/usr/bin/make
/Developer/pcre-8.32/
Contents of my .bashrc file:
export NDK=/Users/Me/Code/Android/android-ndk-r4-crystax
export SDK=/Users/Me/Code/Android/adt-bundle-mac-x86_64-20130219/
export OPCV=/Users/Me/Code/OpenCV/opencv
export PATH=$NDK:$SDK/tools:$SDK/platform-tools:$PATH
export NDK_ROOT=$NDK
Making OpenCV libraries went just fine.
Due to complaint in using make, I had to make a small edit in /Users/Me/Code/OpenCV/opencv/android/android-jni/local.env.mk which looked like so:
#ANDROID_NDK_ROOT=$(HOME)/android-ndk-r4-crystax
ANDROID_NDK_ROOT=/Users/Me/Code/Android/android-ndk-r4-crystax
Then upon trying again to make in the android-jni, directory, disaster struck:
/Users/Me/Code/Android/android-ndk-r4-crystax/ndk-build OPENCV_CONFIG=../build/android-opencv.mk \
PROJECT_PATH= ARM_TARGETS="armeabi armeabi-v7a" V=
Gdbserver : [arm-eabi-4.4.0] /Users/Me/Code/OpenCV/opencv/android/android-jni/libs/armeabi/gdbserver
Gdbsetup : /Users/Me/Code/OpenCV/opencv/android/android-jni/libs/armeabi/gdb.setup
Gdbsetup : + source directory /Users/Me/Code/OpenCV/opencv/android/android-jni/jni
Gdbserver : [arm-eabi-4.4.0] /Users/Me/Code/OpenCV/opencv/android/android-jni/libs/armeabi-v7a/gdbserver
Gdbsetup : /Users/Me/Code/OpenCV/opencv/android/android-jni/libs/armeabi-v7a/gdb.setup
Gdbsetup : + source directory /Users/Me/Code/OpenCV/opencv/android/android-jni/jni
SharedLibrary : libandroid-opencv.so
/Users/Me/Code/Android/android-ndk-r4-crystax/build/prebuilt/darwin-x86/arm-eabi-4.4.0/bin/../lib/gcc/arm-eabi/4.4.0/../../../../arm-eabi/bin/ld: cannot find -lopencv_calib3d
collect2: ld returned 1 exit status
make[1]: *** [/Users/Me/Code/OpenCV/opencv/android/android-jni/obj/local/armeabi/libandroid-opencv.so] Error 1
make: *** [libs/armeabi-v7a/libandroid-opencv.so] Error 2
I thought perhaps this was a pkg-config error, but that appears to be set up as well, though in my old install of OpenCV. Below is the output of pkg-config --cflags --libs opencv:
-I/usr/include/opencv /usr/lib/libopencv_calib3d.dylib /usr/lib/libopencv_contrib.dylib /usr/lib/libopencv_core.dylib /usr/lib/libopencv_features2d.dylib /usr/lib/libopencv_flann.dylib /usr/lib/libopencv_gpu.dylib /usr/lib/libopencv_highgui.dylib /usr/lib/libopencv_imgproc.dylib /usr/lib/libopencv_legacy.dylib /usr/lib/libopencv_ml.dylib /usr/lib/libopencv_nonfree.dylib /usr/lib/libopencv_objdetect.dylib /usr/lib/libopencv_photo.dylib /usr/lib/libopencv_stitching.dylib /usr/lib/libopencv_ts.dylib /usr/lib/libopencv_video.dylib /usr/lib/libopencv_videostab.dylib
The install built by this particular tutorial has placed an opencv.pc file at this location:
/Users/Me/Code/OpenCV/opencv/build/unix-install
BUT Running the below and trying make again doesn't fix the problem:
export PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/Users/Me/Code/OpenCV/opencv/build/unix-install
I can't figure out what is wrong. I've been battling with this problem for about a month on and off, and finally needed some outside opinions. Any ideas?

Error message says
cannot find -lopencv_calib3d collect2: ld returned 1 exit status
It means linker can't find opencv_calib3d library. It may have name libopencv_calib3d.a or libopencv_calib3d.so. So you need find one of them and add path to this file to your LD_LIBRARY_PATH env variable.
I mean if let's say folder /Users/Me/Code/OpenCV/opencv/lib contains libopencv_calib3d.so then you need execute something like following before make:
export LD_LIBRARY_PATH=/Users/Me/Code/OpenCV/opencv/lib:$LD_LIBRARY_PATH

Try the official OpenCV4Android tutorials at http://docs.opencv.org/trunk/doc/tutorials/introduction/android_binary_package/android_dev_intro.html

Setting the location of debug.keystore for command-line build without rewriting Ant targets

When I run "ant debug" from the command line, I get the following error message:
[apkbuilder] keytool error: java.io.FileNotFoundException: \stulab2\folderRedir
ection$.android\debug.keystore (The system cannot find the path specified)
BUILD FAILED
e:\programs\java\android-sdk\tools\ant\build.xml:919: The following error occurred while executing this line:
e:\programs\java\android-sdk\tools\ant\build.xml:930: The following error occurred while executing this line:
e:\programs\java\android-sdk\tools\ant\build.xml:295: com.android.sdklib.build.ApkCreationException: Unable to get debug signature key
at com.android.sdklib.build.ApkBuilder.getDebugKey(ApkBuilder.java:277)
A very long stack trace follows.
The problem is that I am on a public computer and do not have write access to the folder where Ant expects to find .android\debug.keystore. Some research found the following in the Android documentation:
If necessary, you can change the location/name of the debug keystore/key or supply a custom debug keystore/key to use. However, any custom debug keystore/key must use the same keystore/key names and passwords as the default debug key (as described above). (To do so in Eclipse/ADT, go to Windows > Preferences > Android > Build.)
Unfortunately, this doesn't explain how to change the locationof the debug keystore using the command-line tools.
Several months ago, someone asked basically the same question here on stackoverflow: How can I specify location of debug keystore for Android ant debug builds?. The best answer so far is to rewrite the -do-debug target. From what I can tell, I would also need to set the properties specified.
One problem with this answer is that it uses the same properites as the release build does. Also, it would be nice to simply set the correct properties rather than rewriting (and debugging) the whole -do-debug target. Does anyone know if there are properties that can be set to specify the location of the debug.keystore file?

In .bashrc, set the ANDROID_SDK_HOME environment variable to the location of your Android SDK installation. For example:
export ANDROID_SDK_HOME="/home/myusername/path/to/androidsdk"
Then, in a new shell, running ant debug creates a ${ANDROID_SDK_HOME}/.android/debug.keystore file.
Alternatively, without changing the variable globally, you can simply run:
ANDROID_SDK_HOME="/home/myusername/path/to/androidsdk" ant debug