Android build instructions

android/BUILD.txt

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+- Install jdk.
+- Generate app keystore by commond keytool -genkey -alias Hin2n -keystore Hin2n.jks. And remember these two passwords.
+- Move Hin2n.jks to android/Hin2n/app directory. We will use this file to sign the application.
+- Download android tools from https://developer.android.com/, and unzip it.
+
+- Install android development environment.
+echo y | ./tools/bin/sdkmanager tools
+echo y | ./tools/bin/sdkmanager platform-tools
+echo y | ./tools/bin/sdkmanager ndk-bundle
+echo y | ./tools/bin/sdkmanager "cmake;3.6.4111459"
+echo y | ./tools/bin/sdkmanager "lldb;3.1"
+
+- Set environment variables.
+export ANDROID_HOME=YOUE_ANDROID_DEV_HOME
+export ANDROID_NDK_HOME=$ANDROID_HOME/ndk-bundle
+export HIN2N_KSTOREPWD=YOUR_APP_KEYSTORE_PASSWORD
+export HIN2N_KEYPWD=YOUR_APP_KEY_PASSWORD
+
+- Compile the app.
+cd android/Hin2n
+./gradlew assemble
+
+- You will get the app in android/Hin2n/app/build/outputs/apk/ directory.