native

What are native methods in Java and where should they be used? [duplicate]

What are native methods in Java and where should they be used? Once you see a small example, it becomes clear: Main.java: public class Main { public native int intMethod(int i); public static void main(String[] args) { System.loadLibrary(“Main”); System.out.println(new Main().intMethod(2)); } } Main.c: #include <jni.h> #include “Main.h” JNIEXPORT jint JNICALL Java_Main_intMethod( JNIEnv *env, jobject obj, … Read more

Adding new paths for native libraries at runtime in Java

[This solution don’t work with Java 10+] It seems impossible without little hacking (i.e. accessing private fields of the ClassLoader class) This blog provide 2 ways of doing it. For the record, here is the short version. Option 1: fully replace java.library.path with the new value) public static void setLibraryPath(String path) throws Exception { System.setProperty(“java.library.path”, … Read more

How to call methods in Dart portion of the app, from the native platform using MethodChannel?

The signature is void setMethodCallHandler(Future<dynamic> handler(MethodCall call)), so we need to provide a function at the Dart end that returns Future<dynamic>, for example _channel.setMethodCallHandler(myUtilsHandler); Then implement the handler. This one handles two methods foo and bar returning respectively String and double. Future<dynamic> myUtilsHandler(MethodCall methodCall) async { switch (methodCall.method) { case ‘foo’: return ‘some string’; case … Read more

Where to find source code for java.lang native methods? [closed]

For JDK6 you can download the source from java.net. For java.lang the story begins at j2se/src/share/native/java/lang/, and then search… JDK7 rearranges the directory structure a little. Some methods, such as Object.hashCode, may be implemented by hotspot instead or in addition to through JNI/Java. JDK6 is freely licensed through the Java Research License (JRL) and Java … Read more

What is the native keyword in Java for?

Minimal runnable example Main.java public class Main { public native int square(int i); public static void main(String[] args) { System.loadLibrary(“Main”); System.out.println(new Main().square(2)); } } Main.c #include <jni.h> #include “Main.h” JNIEXPORT jint JNICALL Java_Main_square( JNIEnv *env, jobject obj, jint i) { return i * i; } Compile and run: sudo apt-get install build-essential openjdk-7-jdk export JAVA_HOME=’/usr/lib/jvm/java-7-openjdk-amd64′ … Read more