Establish App Development Environment

You can develop a Nexacro Platform-based Android app by using Android Studio, the official app development tool of Android. Otherwise, you can use App Builder, which is one of Nexacro Platform products. This chapter explains how to develop an app by using Android Studio. The process of developing a Nexacro Platform-based Android app is basically the same as that of a usual Android app.

The installation file of Android Studio includes a software development kit (SDK). Click on the below link to download the installation file appropriate for your running environment.

https://developer.android.com/studio/index.html

Develop App Project

Once the app development environment is established, open Android Studio to get ready to develop an app running in Android. Before entering an app project, you should find the archive files that you built in Nexacro Studio and locate them in the designated directory.

Create a project

If you want to create a new project with a project already opened, navigate to the below menu.

File > New > New Project

Selection of templates affects an app structure, screen layout as well as the composition of files. Since it is enough for us to have a basic project that just can contain a Nexacro Platform-based app, select Empty Activity and click Next.

As the project window is opened, additional necessary files are downloaded and installed automatically.

Go to the JDK location option in the menu [File > Project Structure] and select "Use embedded JDK".

Set Nexacro Platform libraries

Libraries provided by Nexacro Platform for developing an Android app include a Java Archive (JAR) file as well as 32-bit and 64-bit shared library (or shared object) files. Without any additional settings, you just need to copy those files to each designated directory to add the libraries to your Android project.

If you want to copy the library files to each designated location in your actual project, you should select the Project view option from the dropdown at the top of the Project window. When you install Android Studio, the view mode is set to Android by default. You should change the view mode to Project to see the actual file structure of a project.

Copy the nexacro17.android.jar file to the directory [project path > app > libs]. For the libnexacro17.so file, navigate to the directory [project path > app > src > main] at first. Then, after creating the [jniLibs > armeabi-v7a] folder for the 32-bit library and [jniLibs > arm64-v8a] folder for the the 64-bit library under the main folder, copy libnexacro17.so to each of the created folders. The below picture shows the resulting folder structure.

You can copy and paste files directly from File Explorer into Android Studio. When you paste a file into each location, the Copy window appears as seen in the below picture to allow you to change the name of the file and the directory where the file is saved. In this sample, just click the OK button without any change.

You should navigate to the Java Archive file that you copied to the project's library directory and add it as a library to allow the project to refer to the file. Right-click on nexacro17.android.jar and select Add As Library from the context menu.

To check whether the library has been added successfully, right-click on your app and select Open Module Settings from the context menu.

Go to the menu Dependencies and check whether the library is added.

Set resources

In this stage, you can set launch images, icons, messages and layouts applied to your app. The Android system can offer optimal settings for screens if you make a list of resources according to device screen sizes and screen densities and then allocate each of them to appropriate folders.

The Android system can determine appropriate resources for certain device screens and screen densities. If there are no appropriate resources for a certain device screen, however, the system will use default resources by scaling them up or down.

The below picture shows the structure of the resource folder, which is automatically created at the creation of a project. Developers distribute image or XML files to each appropriate folder according to resource types.

The format of a resource directory name is <resource type>-<configuration qualifier>. Configuration qualifiers include size (small, normal, large..), density (ldpi, mdpi, hdpi, xhdpi..), orientation (land or port) and screen aspect (long or notlong). For example, the drawable-xxhdpi directory contains images of extra high density and an XML resource file. A directory without a configuration qualifier—for example, drawable—is a folder that contains default resources. Therefore, the drawable directory contains default resources that are used by the system to draw a screen.

See the official Android user guide for further details on resources.

Set images

Images used in an app should be placed in each appropriate directory under the res directory according to screen densities. For example, images for a splash screen should be located in drawable folders while app icon images are placed in mipmap folders. Image files should be put in different folders according to the resolution levels that are supported by the relevant app.

• Set icon images

You can modify icon files after creating a project. Right-click on your app and select [New > Image Asset] from the context menu to open Image Asset Studio. You can configure icon files through the editor.

• Set images of a splash screen

You can simply configure the splash screen displayed while your app is launching. In the above table, the files whose names begin with splashimage_ are splash screen images used in a Nexacro Platform-based app. To set such images, you should copy images to the /res/drawable directory and then change the file names as seen in the below picture.

Set strings

Set the strings used in your app. To this end, modify the strings.xml file as below. strings.xml is a default file created under the directory /res/values when the project is created.

$r_title(strings.xml)
<?xml version="1.0" encoding="utf-8"?>
<resources>
	<!-- The string whose name attribute is "app_name" defines the app name actually used in devices. By changing this string, therefore, you can change the app name displayed on device screens. -->
    <string name="app_name">HelloAndroid</string>
	<string name="action_settings">Settings</string>
    
    <!-- Clipboard -->
    <string name="copy">Copy</string>
    <string name="paste">Paste</string>
    <string name="cut">Cut</string>
    <string name="close">Close</string>
    <string name="selectall">Select All</string>
    <string name="selectword">Select Word</string>
 
    <string name="needupdate">It needs an update. \nAfter completion, Please restart.</string>
    <string name="loadingFail">First loading fails. \nPlease restart.</string>
    <string name="updateFail">Update fails. \nPlease restart.</string>
    <string name="notexist">Start file does NOT exist. \nPlease restart.</string>
    <string name="BeingUpdated">Being updated.</string>
    <string name="wantreplace">There is a file of the same name. Do you want to replace? </string>
    <string name="ok">OK</string>
    <string name="cancel">Cancel</string>
    <string name="move">Move</string>
    <string name="upper">Upper</string>
    <string name="filter">Filter</string>
    <string name="home">Home</string>
    <string name="nofilename">No File Name.</string>     
	<string name="checkforupdates">Check for update.</string>   
	<string name="installforupdates">Install update.</string>  
	<string name="downloadingforupdates">Downloading update.</string>    
	<string name="force_close">Update is Completed.</string> 
	<string name="LoadingPleaseWait">Loading&#8230; \nPlease Wait&#8230;</string> 
	
    <!-- Accessibility widget role -->
    <string name="alert">alert</string>
    <string name="pushbutton">pushbutton</string>
    <string name="combobox">combobox</string>
    <string name="checkbutton">checkbutton</string>
    <string name="radiobutton">radiobutton</string>
    <string name="text">text</string>
    <string name="list">list</string>
    <string name="listitem">listitem</string>
    <string name="statictext"></string>
    <string name="graphic">image</string>
    <string name="spacebar">space bar</string>
    <string name="textdeleted">deleted</string>
    
    <!-- Accessibility widget statue -->
    <string name="checked">checked</string>
    <string name="unchecked">unchecked</string>
    
    <!-- Accessibility reaction -->
    <string name="click">click</string>
    
    <!-- Splash message  -->
    <string name="start_initialize">Start Initialization</string> 
    <string name="check_license">Check License</string>
    <string name="load_frameworkmodule">Load Framework Module</string>
    <string name="load_extendmodule">Load Extended Module</string>
    <string name="execute_frameworkscript">Execute Framework Script</string>
    <string name="load_application">Load Application</string>
    <string name="load_failapplication">Fail to Initialize Application. Click And Close</string>
    
</resources>

While you can change those strings to suit your situation, you should not change their name attributes because they are predefined for the app.

If you want to add strings written in a non-English language like Korean or Japanese, add a folder under the res directory with a name like values-ko or values-ja. Then, add the strings.xml file to the created folder. See the official Android user guide for further details.

Set a layout

Define the layout of your app as displayed on devices. Define the layout structure as shown in the below sample code because the layout is just used to let an Android app hold a Nexacro Platform-based app as a child view. If you do not set a layout, the Nexacro Platform-based app you developed will not be printed on the screen properly when the resulting Android app is launched.

Create a layout XML file under the directory /res/layout with the name nexacro_app.xml and modify the file as below. To add a new layout file, select the menu [File > New > XML > Layout XML File].

$r_title(nexacro_app.xml)

<?xml version="1.0" encoding="utf-8"?>
<!-- nexacro_app.xml -->
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/nexacro_activity"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@android:color/transparent"
    tools:context="com.nexacro.deviceAPI.FileDialogActivity" >

    <com.nexacro.view.NexacroLayout
        android:id="@+id/nexacro_layout"
        android:background="@android:color/transparent"
        android:layout_width="match_parent"
        android:layout_height="match_parent" >
    </com.nexacro.view.NexacroLayout>

</FrameLayout>

Set Config

Set the nexacro_config.xml file to apply the functionalities provided by Nexacro Platform to your app. You can activate features including app updating, notification and error processing. You should create the nexacro_config.xml file by yourself and locate the file under the directory [Project > app > src > main > res > xml]. This file should be included in the project when your app is built in Android Studio.

The nexacro_config.xml file is in the XML format and written like the below sample.

<?xml version="1.0" encoding="UTF-8"?>
<nexacro-config>
    <application dialog-position="center" file-logging="true" quiet="false"/>
    <updator cancelable="true" force="true" errormsg="true" quiet="false"/>
    <xpush-server requestMissingMessage="true"/>
    <notification enable="true" handler="com.nexacro.notification.DefaultHandler"/>
</nexacro-config>

The below table shows the features that you can set in nexacro_config.xml.

Set build environment

You should modify MainActivity.java and AndroidManifest.xml —default files created in the process of creating an Android project—in a way that suits Nexacro Platform.

MainActivity.java

If you do not specify another name for a main activity at the creation of a project, the activity will be created with the name MainActivity.java. To find the file MainActivity.java, navigate to the folder of the relevant package name under the directory [project > app > src > main > java]. Then, modify the file as below.

$r_title(MainActivity.java)


package com.example.helloandroid;

import com.nexacro.NexacroResourceManager;
import com.nexacro.NexacroUpdatorActivity;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;

public class MainActivity extends NexacroUpdatorActivity {

    public MainActivity() {
        super();

        setBootstrapURL("http://[URL]/start_android.json");
        setProjectURL("http://[URL]/");
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        NexacroResourceManager.createInstance(this);
        NexacroResourceManager.getInstance().setDirect(false);

        Intent intent = getIntent();
        if(intent != null) {
            String bootstrapURL = intent.getStringExtra("bootstrapURL");
            String projectUrl = intent.getStringExtra("projectUrl");
            if(bootstrapURL != null) {
                setBootstrapURL(bootstrapURL);
                setProjectURL(projectUrl);
            }
        }

        super.onCreate(savedInstanceState);
    }

    @Override
    public void setContentView(View view) {
        super.setContentView(view);
    }

}

In the above sample, the text written in bold should be replaced with something appropriate for your settings.

The 15^th and 16^th lines are written to designate two addresses: one is for a bootstrap and the other is for the project's source code. As an argument of the setBootstrapURL method, you should specify the server URL for the start_android.json file, which is created in Nexacro Studio. As an argument of the setProjectURL method, you should specify the server URL for the directory where the source code of the relevant project is generated. You should add a slash (/) at the end of the path to the generated source code.

15 setBootstrapURL("http://192.168.0.1:8080/nexacro/_android_/start_android.json");
16 setProjectURL("http://192.168.0.1:8080/nexacro/_android_/");

The 22^nd and 23^rd lines should be adjusted according to the update type, which is set in the Packing (Archive&Update) stage of Nexacro Studio. If the update type is set to "Server", you should specify "true" as an argument of the setDirect method written in the 23^rd line. If the update type is set to "Update (Local+Server)" or "Local", you should specify "false".

22 NexacroResourceManager.createInstance(this);
23 NexacroResourceManager.getInstance().setDirect(true);

In the 17.0.0.2100 version or later, you can change the value of the screenid property by using the setScreenid method with the onCreate callback.

public void onCreate(Bundle savedInstanceState) {
    NexacroResourceManager.createInstance(this);
    NexacroResourceManager.getInstance().setScreenid("Tablet_screen");
}

AndroidManifest.xml

The AndroidManifest.xml file, which is located in the directory [project > app > src > main], contains basic information about your app and necessary information for performing specific functionalities. Modify the file as shown in the below sample. Moreover, the information about the package and main activity—the two pieces of text in bold in the below sample—should be changed according to the settings of your project.

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.helloandroid">

    <uses-feature
        android:glEsVersion="0x00020000"
        android:required="true" />

    <!-- network access Permission -->
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
    <uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
    <uses-permission android:name="android.permission.CHANGE_NETWORK_STATE" />

	<!-- storage access permission -->
	<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
	<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
	<uses-permission android:name="android.permission.READ_INTERNAL_STORAGE" />
	<uses-permission android:name="android.permission.WRITE_INTERNAL_STORAGE" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">

        <activity
            android:name="com.example.helloandroid.MainActivity"
            android:label="@string/app_name"
            android:theme="@android:style/Theme.NoTitleBar">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <activity
            android:name="com.nexacro.NexacroActivity"
            android:alwaysRetainTaskState="true"
            android:configChanges="orientation|keyboardHidden|screenSize"
            android:launchMode="singleTop"
            android:theme="@android:style/Theme.NoTitleBar"
            android:windowSoftInputMode="adjustResize" >
        </activity>

		<!-- FileDialog -->
		<activity android:name="com.nexacro.deviceAPI.FileDialogActivity" android:screenOrientation="sensor">
			<intent-filter>
				<category android:name="android.intent.category.LAUNCHER" />
			</intent-filter>
		</activity>

        <meta-data
            android:name="com.google.android.gms.version"
            android:value="google_play_services_version" />

    </application>

</manifest>

Set necessary permissions and other information according to the features that your app is equipped with. For example, add the below sample to the manifest file if you want your app to provide the camera feature.

...
<uses-permission android:name="android.permission.CAMERA" />
<activity android:name="com.nexacro.deviceAPI.CameraListener"
	android:screenOrientation="landscape">
	<intent-filter>
   		<category android:name="android.intent.category.LAUNCHER" />
	</intent-filter>
</activity>
<uses-feature android:name="android.hardware.camera" android:required="false"/>
<uses-feature android:name="android.hardware.camera.autofocus"
	android:required="false"/>
...

The below list contains sets of code to set the permissions for frequently-used features. Pick items necessary for your app and add them to AndroidManifest.xml. If you want to see all the permissions defined in Android, go to Manifest.permission.

<!-- AudioPlayer, AudioRecorder -->
<uses-permission android:name="android.permission.RECORD_AUDIO" /> 
<uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS" />

<!-- Call -->
<uses-permission android:name="android.permission.CALL_PHONE" />

<!-- Contact -->
<uses-permission android:name="android.permission.READ_CONTACTS" /> 
<uses-permission android:name="android.permission.WRITE_CONTACTS" />

<!-- Camera -->
<uses-permission android:name="android.permission.CAMERA" /> 
<activity android:name="com.nexacro.deviceAPI.CameraListener" android:screenOrientation="landscape">
	<intent-filter>
    	<category android:name="android.intent.category.LAUNCHER" />
	</intent-filter>
</activity>
<uses-feature android:name="android.hardware.camera" android:required="false"/>
<uses-feature android:name="android.hardware.camera.autofocus" android:required="false"/>

<!-- Geolocation -->
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_LOCATION_EXTRA_COMMANDS" />

<!-- Map -->
<uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES"/>
<uses-library android:name="com.google.android.maps" /> 
<meta-data android:name="com.google.android.maps.v2.API_KEY" android:value="user value" />

Nexacro Platform has adopted Firebase Cloud Messaging (FCM) since the version 17.0.0.1800.

<!-- Adding NexacroNotificationService -->
<service android:name="com.nexacro.notification.NexacroNotificationService">
	<intent-filter>
		<action android:name="com.google.firebase.MESSAGING_EVENT" />
	</intent-filter>
</service>

<!-- Adding NexacroActivity intent-filter -->
<activity android:name="com.nexacro.NexacroActivity"
	android:launchMode="singleTask"
	android:noHistory="false"
	android:hardwareAccelerated="true"
	android:windowSoftInputMode="adjustResize"
	android:configChanges="orientation|keyboard|keyboardHidden|screenSize|navigation|uiMode">
	<intent-filter>
		<action android:name="OPEN_NEXACRO_ACTIVITY_EXAMPLE" />
		<category android:name="android.intent.category.DEFAULT" />
	</intent-filter>
</activity>

If you use FCM, the below code listings should be added to the build.gradle file. Basically, this configuration is automatically performed in Android Studio. If not performed automatically, however, you need to add the below code listings by yourself and download the google-services.json file, which is created in the Firebase console. Then, copy the JSON file to the module directory of your app.

buildscript {
	// Adding repositories 
	repositories {
		google()  
		jcenter()
	}
	dependencies {
		classpath 'com.android.tools.build:gradle:3.2.1'
		// NOTE: Do not place your application dependencies here; they belong
		// in the individual module build.gradle files
		// Adding google service
		classpath 'com.google.gms:google-services:4.0.1'
	}
}

allprojects {
	// Adding repositories 
	repositories {
		google()
		jcenter()
	}
}

task clean(type: Delete) {
	delete rootProject.buildDir
}

dependencies {
	implementation fileTree(include: ['*.jar'], dir: 'libs')
	implementation 'com.android.support:appcompat-v7:27.1.1'
	implementation 'com.android.support:support-v4:27.1.1'
	implementation 'com.google.android.gms:play-services-maps:16.0.0'
	implementation 'com.google.android.gms:play-services-location:16.0.0'
	implementation 'com.google.firebase:firebase-core:16.0.6'
	implementation 'com.google.firebase:firebase-messaging:17.3.4'
	compile 'com.android.support:multidex:1.0.3'
	implementation 'com.android.support:design:27.1.1'
	implementation files('libs/nexacro17.android.jar')
}
apply plugin: 'com.google.gms.google-services'

<!-- SMS -->
<uses-permission android:name="android.permission.SEND_SMS" /> 
<uses-permission android:name="android.permission.RECEIVE_SMS" /> 
<uses-permission android:name="android.permission.READ_SMS" /> 
<uses-permission android:name="android.permission.WRITE_SMS" />

<receiver android:name="com.nexacro.deviceAPI.SmsRecv">
	<intent-filter>
		<action android:name="android.provider.Telephony.SMS_RECEIVED" />
	</intent-filter>
	<intent-filter>
		<action android:name="android.provider.Telephony.WAP_PUSH_RECEIVED" />
		<data android:mimeType="application/vnd.wap.mms-message" />
	</intent-filter>
</receiver>

<!-- Vibrator -->
<uses-permission android:name="android.permission.VIBRATE" />

<!-- FileDialog -->
<activity android:name="com.nexacro.deviceAPI.FileDialogActivity" android:screenOrientation="sensor">
	<intent-filter>
		<category android:name="android.intent.category.LAUNCHER" />
	</intent-filter>
</activity>

<!-- Bluetooth -->
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />

<service
	android:name="com.nexacro.deviceAPI.BluetoothLEAdapterService"
	android:enabled="true"
	android:exported="true">
</service>

<!-- ExternalAPI -->
<uses-permission android:name="android.permission.GET_TASKS" />

<!-- Etc -->
<uses-permission android:name="android.permission.GET_ACCOUNTS" />
<uses-permission android:name="android.permission.READ_PHONE_STATE" />

Set your app stand-alone in disconnected environments

You can run your app without a network connection if you set the update type to "Local" or "Update (Local+Server)" when packing the app in Nexacro Studio. Normally, the Local type is appropriate for users who do not need a network connection while the Update (Local+Server) type suits users who usually maintain communications with servers but still need to operate apps even when networking is in trouble. To make your app stand-alone, you should prepare files necessary for execution and load them onto the app in the building process.

The files necessary for executing an app include modules, sources, resources and start_android.json, which are all obtained through the Packing (Archive&Update) process of Nexacro Studio. If you load those files onto the "archive" folder under the "assets" directory in your Android project before building an app, you can run the app without a network connection.

Right-click on app, the root folder of your project, and select [New > Folder > Assets Folder] from the context menu. Create the assets folder under the directory [project > app > src > main].

Right-click the assets folder under the directory [project > app > src > main] and select [New > Directory] from the context menu to create the "archive" folder under the assets folder.

Copy module, source and resource files to the [project > app > src > main > assets > archive] directory. You can copy and paste files directly from File Explorer into Android Studio.

Go to the project view in Android Studio and check whether the added assets/archive folder and files under the folder are there.

Build

App test

1. You can test your app by connecting an Android device to your PC using a USB cable. In that case, you need to toggle the USB debugging option in the Developer Options menu in the device and to install a driver for the device.

2. Select the Run menu of Android Studio, which allows you to build an APK, install it on your device and then execute the app. Upon selecting the menu, you can choose a device for running your app.

Run > Run 'App'

You can see the log messages for executing the app through the Logcat window, which is situated at the bottom of the Android Studio screen.

Create installation file

To distribute your app that has been built completely, you should create a keystore that can identify your app and then should create a signed APK file. You need to create a keystore file just once at the beginning. When the app is updated, you can use the keystore file that you created already.

Click on the below link to go to the official Android user guide where you can learn how to create a keystore and signed APK.

Select the menu [Build > Generate Singed Bundle/APK].