yaohuiwu / hellojni

HelloJNI is a simple android project to demonstrate how to use JNI in android platform.

What is HelloJNI

HelloJNI is a simple android project to demonstrate how to use JNI in android platform.

requirements

• os

  • Ubuntu 14.04 LTS

• jdk

  • 1.7

• gradle

  • 2.9

• android sdk

  • Android SDK Tool 24.4.1
  • Android SDK Platform-tools 23.0.1
  • Android SDK Build-tools 23.0.2
  • SDK Platform 4.3.1 (API 18)
  • Android Support Respository 25
  • Android Support Library 23.1.1

• android ndk

  • r10

• android stdio

  • 141.2422023

how to build

1. build libHelloJNI.so manually.

    cd app/src/main/jni
    /path/to/ndk-build
   

2. build by gradle.

    gradle build
   

how to create jni header file

1. compile java source file that contain native methods.

    cd app/src/main/java/com/example/yaohui/testjni
    javac HelloJNI.java
   

2. create jni header file.

    cd app/src/main/java
    javah -classpath .  -d /path/to/app/src/main/jni -jni com.example.yaohui.testjni.HelloJNI
   

some note in developing native code

• The method signature in jni header ignore method parameters, which should not be ignore in implementation.