SQLite with Android NDK
Just download the SQLite3 amalgamation source file from: http://www.sqlite.org/download.html And then add sqlite3.c to your LOCAL_SRC_FILES variable in Android.mk.
java-native-interface
passing string array from java to C with JNI
You can write a simple function that takes a jobjectArray object, cast each one to jstring and then call GetStringUTFChars on it. Like this: void MyJNIFunction(JNIEnv *env, jobject object, jobjectArray stringArray) { int stringCount = env->GetArrayLength(stringArray); for (int i=0; i<stringCount; i++) { jstring string = (jstring) (env->GetObjectArrayElement(stringArray, i)); const char *rawString = env->GetStringUTFChars(string, 0); // … Read more
Android NDK java.lang.UnsatisfiedLinkError: findLibrary returned null
If you have a native project with LOCAL_MODULE “libXYZ”, make sure to load it as System.loadLibrary(“XYZ”);
how to make jni.h be found?
You have to tell your compiler where is the include directory. Something like this: gcc -I/usr/lib/jvm/jdk1.7.0_07/include But it depends on your makefile.
Eclipse reported “Failed to load JNI shared library” [duplicate]
First, ensure that your version of Eclipse and JDK match, either both 64-bit or both 32-bit (you can’t mix-and-match 32-bit with 64-bit). Second, the -vm argument in eclipse.ini should point to the java executable. See http://wiki.eclipse.org/Eclipse.ini for examples. If you’re unsure of what version (64-bit or 32-bit) of Eclipse you have installed, you can determine … Read more
How to use the same C++ code for Android and iOS?
Update. This answer is quite popular even four years after I write it, in this four years a lot of things has changed, so I decided to update my answer to fit better our current reality. The answer idea does not change; the implementation has changed a little. My English also has changed, it has … Read more
how to set java library path for processing
You can set it on the command line thus: java -Djava.library.path=… <existing arguments (classpath, name of class to run etc.)> and point it to the directory containing the relevant library.
What is a native implementation in Java? [duplicate]
These methods are either Intrinsic or written outside Java in “native” code, that is, specific to the given machine. The ones you mention are Intrinsic and part of the JDK but you can also write native methods yourself using the Java Native Interface (JNI). This would normally use C to write the methods, but a … Read more
How to call C++ from Java?
While I’ve used JNI-C++ bridging in the past (only a little though) – it can be a bit ugly. You might want to consider using SWIG to help you generate all the messy boiler plate code.
Converting from signed char to unsigned char and back again?
This is one of the reasons why C++ introduced the new cast style, which includes static_cast and reinterpret_cast There’s two things you can mean by saying conversion from signed to unsigned, you might mean that you wish the unsigned variable to contain the value of the signed variable modulo the maximum value of your unsigned … Read more