Merge pull request android#209 from ggfan/hello-jnicallback

Create hello-jnicallback sample to complete hello-jni

hello-jniCallback/.google/packaging.yaml

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+status:       PUBLISHED
+technologies: [Android, NDK]
+categories:   [NDK]
+languages:    [C++, Java]
+solutions:    [Mobile]
+github:       googlesamples/android-ndk
+license:      apache2

hello-jniCallback/README.md

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+Hello JNI Callback
+==================
+This sample is an Aadd-on to Hello JNI sample to demonstrate calling back to Java from C code
+- create a java class instance from C code
+- call java class static and non-static member functions
+
+This sample uses the new [Gradle Experimental Android plugin](http://tools.android.com/tech-docs/new-build-system/gradle-experimental) with C++ support.
+
+Pre-requisites
+--------------
+- Android Studio 1.3+ with [NDK](https://developer.android.com/ndk/) bundle.
+
+Getting Started
+---------------
+1. [Download Android Studio](http://developer.android.com/sdk/index.html)
+1. Launch Android Studio.
+1. Open the sample directory.
+1. Open *File/Project Structure...*
+  - Click *Download* or *Select NDK location*.
+1. Click *Tools/Android/Sync Project with Gradle Files*.
+1. Click *Run/Run 'app'*.
+
+Screenshots
+-----------
+![screenshot](screenshot.png)
+
+Support
+-------
+If you've found an error in these samples, please [file an issue](https://github.com/googlesamples/android-ndk/issues/new).
+
+Patches are encouraged, and may be submitted by [forking this project](https://github.com/googlesamples/android-ndk/fork) and
+submitting a pull request through GitHub. Please see [CONTRIBUTING.md](../CONTRIBUTING.md) for more details.
+
+- [Stack Overflow](http://stackoverflow.com/questions/tagged/android-ndk)
+- [Google+ Community](https://plus.google.com/communities/105153134372062985968)
+- [Android Tools Feedbacks](http://tools.android.com/feedback)
+
+License
+-------
+Copyright 2015 Google, Inc.
+
+Licensed to the Apache Software Foundation (ASF) under one or more contributor
+license agreements.  See the NOTICE file distributed with this work for
+additional information regarding copyright ownership.  The ASF licenses this
+file to you under the Apache License, Version 2.0 (the "License"); you may not
+use this file except in compliance with the License.  You may obtain a copy of
+the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+License for the specific language governing permissions and limitations under
+the License.

hello-jniCallback/app/build.gradle

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+apply plugin: 'com.android.model.application'
+
+model {
+    android {
+        compileSdkVersion = 23
+        buildToolsVersion = "23.0.2"
+
+        defaultConfig {
+            applicationId = "com.example.hello_jnicallback"
+            minSdkVersion.apiLevel = 15
+            targetSdkVersion.apiLevel = 23
+            versionCode = 1
+            versionName = '1.0'
+        }
+        ndk {
+            moduleName = 'hello-jnicallback'
+            ldLibs.addAll(['android', 'log'])
+        }
+        buildTypes {
+            release {
+                minifyEnabled = false
+                proguardFiles.add(file('proguard-android.txt'))
+            }
+        }
+    }
+}
+
+dependencies {
+    compile fileTree(dir: 'libs', include: ['*.jar'])
+    compile 'com.android.support:appcompat-v7:23.3.0'
+}

hello-jniCallback/app/proguard-rules.pro

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+# Add project specific ProGuard rules here.
+# By default, the flags in this file are appended to flags specified
+# in /Users/gfan/dev/sdk_current/tools/proguard/proguard-android.txt
+# You can edit the include path and order by changing the proguardFiles
+# directive in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# Add any project specific keep options here:
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}

hello-jniCallback/app/src/main/AndroidManifest.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.example.hello_jnicallback">
+
+    <application
+        android:allowBackup="true"
+        android:icon="@mipmap/ic_launcher"
+        android:label="@string/app_name"
+        android:supportsRtl="true"
+        android:theme="@style/AppTheme">
+        <activity android:name=".MainActivity">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+    </application>
+
+</manifest>

hello-jniCallback/app/src/main/java/com/example/hello_jnicallback/JniHandler.java

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+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+package com.example.hello_jnicallback;
+
+import android.os.Build;
+import android.support.annotation.Keep;
+import android.util.Log;
+
+/*
+ * A helper class to demo that JNI could call into:
+ *     private non-static function
+ *     public non-static function
+ *     static public function
+ * The calling code is inside hello-jnicallback.c
+ */
+public class JniHandler {
+    /*
+     * Print out status to logcat
+     */
+    @Keep
+    private void updateStatus(String msg) {
+        if (msg.toLowerCase().contains("error")) {
+            Log.e("JniHandler", "Native Err: " + msg);
+        } else {
+            Log.i("JniHandler", "Native Msg: " + msg);
+        }
+    }
+
+    /*
+     * Return OS build version: a static function
+     */
+    @Keep
+    static public String getBuildVersion() {
+        return Build.VERSION.RELEASE;
+    }
+
+    /*
+     * Return Java memory info
+     */
+    @Keep
+    public long getRuntimeMemorySize() {
+        return Runtime.getRuntime().freeMemory();
+    }
+}

hello-jniCallback/app/src/main/java/com/example/hello_jnicallback/MainActivity.java

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+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+package com.example.hello_jnicallback;
+
+import android.support.annotation.Keep;
+import android.support.v7.app.AppCompatActivity;
+import android.os.Bundle;
+import android.widget.TextView;
+
+public class MainActivity extends AppCompatActivity {
+    int hour = 0;
+    int minute = 0;
+    int second = 0;
+    TextView tickView;
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_main);
+        tickView = (TextView) findViewById(R.id.tickView);
+    }
+    @Override
+    public void onResume() {
+        super.onResume();
+        hour = minute = second = 0;
+        ((TextView)findViewById(R.id.hellojniMsg)).setText(stringFromJNI());
+        startTicks();
+    }
+
+    @Override
+    public void onPause () {
+        super.onPause();
+        StopTicks();
+    }
+
+    /*
+     * A function calling from JNI to update current timer
+     */
+    @Keep
+    private void updateTimer() {
+        ++second;
+        if(second >= 60) {
+            ++minute;
+            second -= 60;
+            if(minute >= 60) {
+                ++hour;
+                minute -= 60;
+            }
+        }
+        runOnUiThread(new Runnable() {
+            @Override
+            public void run() {
+                String ticks = "" + MainActivity.this.hour + ":" +
+                        MainActivity.this.minute + ":" +
+                        MainActivity.this.second;
+                MainActivity.this.tickView.setText(ticks);
+            }
+        });
+    }
+    static {
+        System.loadLibrary("hello-jnicallback");
+    }
+    public native  String stringFromJNI();
+    public native void startTicks();
+    public native void StopTicks();
+
+}