Cmake Can't Find Java, But It's Installed

cmake can't find java, but it's installed

If you are using the linux os then you have to set the java home like export

JAVA_HOME=/home/aqeel/development/jdk/jdk1.6.0_35   
export PATH=$JAVA_HOME/bin:$PATH

CMake could not find JNI

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.

CMake cannot find Java on Linux Could NOT find Java (missing: Java_JAVAH_EXECUTABLE)

It looks like cmake is looking for javah not javac. You're using Java 1.8, so you should have javah installed. (It has been removed in a later version, and instead of javah you're supposed to use javac -h)

Make sure cmake can find the javah tool by setting JAVA_HOME so that it points at the Java 8 installation directory (typically under /usr/lib/jvm on a Linux system)

C++/CMake can't find libxml++

You may should add this line to your CMakeLists.txt :

include_directories("/usr/include/libxml++2.6/")

( or use any macro to achieve to this result )

then in your main :

#include <iostream>
#include <libxml++/libxml++.h> // <= like this

int main() {
    std::cout << "hello" << std::endl;
}

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Another way to do :

If it do not fix your problem you can also try to go to the libxml++ page : https://developer.gnome.org/libxml++-tutorial/stable/chapter-introduction.html .

Here you have a link to download libxml++.

Then you just have to follow the instruction in the file call INSTALL, and add the include directory with :

include_directories("<your-path/libxml++2.6>")

and add a new library path for your compilator when it search lib with

link_directories("<your-other-path>/lib")

Hoping it help you

cmake for OpenCV doesn't detect jdk

I solved it. Cmake for opencv needs ANT, but I didn't have it. For now cmake can make opencv with java support.

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