jni integration working

Author: efraespada

.gitignore

@@ -3,4 +3,5 @@
 .gradle/
 build/
 local.properties
+library/.externalNativeBuild
 *.iml

app/build.gradle

@@ -37,8 +37,8 @@ dependencies {
     })
     implementation 'com.android.support:appcompat-v7:28.0.0'
     testImplementation 'junit:junit:4.12'
-    // implementation project(path: ':library')
-    implementation "com.stringcare:library:$stringcare_version"
+    implementation project(path: ':library')
+    // implementation "com.stringcare:library:$stringcare_version"
 }
 
 

library/CMakeLists.txt

@@ -0,0 +1,44 @@
+# For more information about using CMake with Android Studio, read the
+# documentation: https://d.android.com/studio/projects/add-native-code.html
+
+# Sets the minimum version of CMake required to build the native library.
+
+cmake_minimum_required(VERSION 3.4.1)
+
+# Creates and names a library, sets it as either STATIC
+# or SHARED, and provides the relative paths to its source code.
+# You can define multiple libraries, and CMake builds them for you.
+# Gradle automatically packages shared libraries with your APK.
+
+add_library( # Sets the name of the library.
+        native-lib
+
+        # Sets the library as a shared library.
+        SHARED
+
+        # Provides a relative path to your source file(s).
+        src/main/cpp/native-lib.cpp)
+
+# Searches for a specified prebuilt library and stores the path as a
+# variable. Because CMake includes system libraries in the search path by
+# default, you only need to specify the name of the public NDK library
+# you want to add. CMake verifies that the library exists before
+# completing its build.
+
+find_library( # Sets the name of the path variable.
+        log-lib
+
+        # Specifies the name of the NDK library that
+        # you want CMake to locate.
+        log)
+
+# Specifies libraries CMake should link to your target library. You
+# can link multiple libraries, such as libraries you define in this
+# build script, prebuilt third-party libraries, or system libraries.
+
+target_link_libraries( # Specifies the target library.
+        native-lib
+
+        # Links the target library to the log library
+        # included in the NDK.
+        ${log-lib})

library/build.gradle

@@ -13,9 +13,12 @@ android {
         targetSdkVersion 28
         versionCode 4
         versionName version
-
         testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
-
+        externalNativeBuild {
+            cmake {
+                cppFlags "-fexceptions"
+            }
+        }
     }
     buildTypes {
         release {
@@ -27,6 +30,11 @@ android {
             proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
         }
     }
+    externalNativeBuild {
+        cmake {
+            path "CMakeLists.txt"
+        }
+    }
 }
 
 dependencies {

library/src/main/cpp/native-lib.cpp

@@ -0,0 +1,10 @@
+#include <jni.h>
+#include <string>
+
+extern "C" JNIEXPORT jstring JNICALL
+Java_com_stringcare_library_SC_stringFromJNI(
+        JNIEnv *env,
+        jobject /* this */) {
+    std::string hello = "Hello from C++";
+    return env->NewStringUTF(hello.c_str());
+}

library/src/main/java/com/stringcare/library/SC.java

@@ -40,9 +40,20 @@ public class SC {
     private static Context context;
     private static List<ContextListener> listeners = new ArrayList<>();
 
+    static {
+        System.loadLibrary("native-lib");
+    }
+
     private SC () {
         // nothing to do here
     }
+
+    /**
+     * A native method that is implemented by the 'native-lib' native library,
+     * which is packaged with this application.
+     */
+    public static native String stringFromJNI();
+
     public static void init(Context c) {
         context = c;
         if (!listeners.isEmpty()) {
@@ -171,6 +182,7 @@ private static String byteArrayToHexString(byte[] bytes) {
      * @return String
      */
     public static String getString(@StringRes int id) {
+        if (true) return SC.stringFromJNI();
         if (context == null) {
             Log.e(TAG, "Library not initialized: SC.init(Context)");
             return null;