Android Mobile Application Implementation (Mobile Apps + API)

This document is part of the Mobile + API Architecture Scenario and it explains how to implement the mobile application in Android. Please refer to the scenario for information on the implemented solution.

1. Set Up the Application

Sample Project

Download a sample project specific to this tutorial to get started.

Download Fork on Github

System Requirements

Android Studio 2.3
Android SDK 25
Emulator - Nexus 5X - Android 6.0

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Set the Dependencies

For this implementation, we will use the following dependencies within the app’s build.gradle file:

Auth0.Android: this package enables integration with Auth0 to authenticate users.
OkHttp: this package provides an HTTP application to make requests to the Node.JS API.
JWTDecode.Android: this package will assist with decoding JWTs.
AppCompat: this package lets us use the toolbar widget for navigation in our activities.

dependencies {
    compile 'com.squareup.okhttp:okhttp:2.7.5'
    compile 'com.auth0.android:auth0:1.10.0'
    compile 'com.auth0.android:jwtdecode:1.1.1'
    compile 'com.android.support:appcompat-v7:25.3.1'
    testCompile 'junit:junit:4.12'
}

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Update the Manifest

Open the application's AndroidManifest.xml and add the internet permission:

<uses-permission android:name="android.permission.INTERNET" />

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We’ll also update the application details to utilize the Toolbar widget:

<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/Theme.AppCompat.Light.NoActionBar">
    </application>

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Set Configuration Values

Set your Auth0 Client ID, Auth0 Domain, and API’s url in the strings.xml resource located in /res/values/strings.xml:

<resources>
    <string name="app_name">ExampleCo Timesheets</string>
    <string name="login">Log in</string>
    <string name="auth0_client_id">...</string>
    <string name="auth0_domain">...</string>
    <string name="api_url">http://10.0.2.2:8080/timesheets</string>
</resources>

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For this implementation, create directories for activities, models, and utils in the application package.

activities/: this package will contain the LoginActivity.java, TimeSheetActivity.java, FormActivity.java, and UserActivity.java.
models/: this package will contain the TimeSheet.java and User.java data models.
utils/: this package will contain the UserProfileManager.java, TimeSheetAdapter.java, and ImageTask.java

2. Authorize the User

Update the Manifest

Open the app's AndroidManifest.xml and add the LoginActivity:

<activity
            android:name="com.auth0.samples.activities.LoginActivity"
            android:launchMode="singleTask">

            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>

            <intent-filter>
                <action android:name="android.intent.action.VIEW" />

                <category android:name="android.intent.category.DEFAULT" />
                <category android:name="android.intent.category.BROWSABLE" />

                <data
                    android:host="@string/auth0_domain"
                    android:pathPrefix="/android/com.auth0.samples/callback"
                    android:scheme="demo" />
            </intent-filter>
</activity>

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The LoginActivity will handle user authorization and be the initial screen users see. We'll create a login() method to initialize a WebAuthProvider and start authentication. Ensure you provide the correct scheme, audience, and scope to the WebAuthProvider. For this implementation we will use:

scheme: demo
audience: https://api.exampleco.com/timesheets (the Node.JS API)
response_type: code
scope: create:timesheets read:timesheets openid profile email offline_access. These scopes will enable us to POST and GET to the Node.JS API, as well as retrieve the user profile and a Refresh Token.

private void login() {
        Auth0 auth0 = new Auth0(getString(R.string.auth0_client_id), getString(R.string.auth0_domain));
        auth0.setOIDCConformant(true);

        WebAuthProvider.init(auth0)
                .withScheme("demo")
                .withAudience("https://api.exampleco.com/timesheets")
                .withResponseType(ResponseType.CODE)
                .withScope("create:timesheets read:timesheets openid profile email offline_access")
                .start(
                    // ...
                );
}

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In the login() method, upon successful authentication we'll redirect the user to the TimeSheetActivity.

package com.auth0.samples.activities;

import android.app.Activity;
import android.app.Dialog;
import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

import com.auth0.android.Auth0;
import com.auth0.android.authentication.AuthenticationException;
import com.auth0.android.jwt.JWT;
import com.auth0.android.provider.AuthCallback;
import com.auth0.android.provider.ResponseType;
import com.auth0.android.provider.WebAuthProvider;
import com.auth0.android.result.Credentials;
import com.auth0.samples.R;
import com.auth0.samples.models.User;
import com.auth0.samples.utils.CredentialsManager;
import com.auth0.samples.utils.UserProfileManager;

public class LoginActivity extends Activity {

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.login_activity);
        Button loginWithTokenButton = (Button) findViewById(R.id.loginButton);
        loginWithTokenButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                login();
            }
        });
    }

    @Override
    protected void onNewIntent(Intent intent) {
        if (WebAuthProvider.resume(intent)) {
            return;
        }
        super.onNewIntent(intent);
    }

    private void login() {
        Auth0 auth0 = new Auth0(getString(R.string.auth0_client_id), getString(R.string.auth0_domain));
        auth0.setOIDCConformant(true);

        WebAuthProvider.init(auth0)
                .withScheme("demo")
                .withAudience("https://api.exampleco.com/timesheets")
                .withResponseType(ResponseType.CODE)
                .withScope("create:timesheets read:timesheets openid profile email")
                .start(LoginActivity.this, new AuthCallback() {
                    @Override
                    public void onFailure(@NonNull final Dialog dialog) {
                        runOnUiThread(new Runnable() {
                            @Override
                            public void run() {
                                dialog.show();
                            }
                        });
                    }

                    @Override
                    public void onFailure(final AuthenticationException exception) {
                        runOnUiThread(new Runnable() {
                            @Override
                            public void run() {
                                Toast.makeText(LoginActivity.this, "Error: " + exception.getMessage(), Toast.LENGTH_SHORT).show();
                            }
                        });
                    }

                    @Override
                    public void onSuccess(@NonNull final Credentials credentials) {
                        runOnUiThread(new Runnable() {
                            @Override
                            public void run() {
                                Toast.makeText(LoginActivity.this, "Log In - Success", Toast.LENGTH_SHORT).show();
                            }
                        });
                        startActivity(new Intent(LoginActivity.this, TimeSheetActivity.class));
                    }
                });
    }
}

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Store the Credentials

To store the credentials received after login, we’ll use the CredentialsManager from the Auth0.Android library and SharedPreferences for storage.

Before initializing the WebAuthProvider in the login() method, we can create the CredentialsManager. Passing an AuthenticationAPIClient to the CredentialsManager enables it to refresh the Access Tokens if they are expired.

private void login() {
        Auth0 auth0 = new Auth0(getString(R.string.auth0_client_id), getString(R.string.auth0_domain));
        auth0.setOIDCConformant(true);

        AuthenticationAPIClient authAPIClient = new AuthenticationAPIClient(auth0);
        SharedPreferencesStorage sharedPrefStorage = new SharedPreferencesStorage(this);
        final CredentialsManager credentialsManager = new CredentialsManager(authAPIClient, sharedPrefStorage);

        WebAuthProvider.init(auth0)
        // ...
    }

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Now update the login() method so that credentials are stored via the CredentialsManager after a successful authentication.

// ...
@Override
public void onSuccess(@NonNull final Credentials credentials) {
    runOnUiThread(new Runnable() {
        @Override
        public void run() {
            Toast.makeText(LoginActivity.this, "Log In - Success", Toast.LENGTH_SHORT).show();
        }
    });

    credentialsManager.saveCredentials(credentials);
    startActivity(new Intent(LoginActivity.this, TimeSheetActivity.class));
// ...
}

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3. Get the User Profile

Create the User Model

Create a simple User model that will be utilized by the UserProfileManager and UserActivity.

package com.auth0.samples.models;

public class User {
    private String email;
    private String name;
    private String pictureURL;

    public User(String email, String name, String pictureURL) {
        this.email = email;
        this.name = name;
        this.pictureURL = pictureURL;
    }

    public String getEmail() {
        return email;
    }

    public String getName() {
        return name;
    }

    public String getPictureURL() {
        return pictureURL;
    }
}

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Store the User Profile

To handle storing user profile information we'll create a manager class UserProfileManager. The UserProfileManager will use SharedPreferences to store data.

package com.auth0.samples.utils;

import android.content.Context;
import android.content.SharedPreferences;

import com.auth0.android.result.UserProfile;
import com.auth0.samples.models.User;

public class UserProfileManager {

    private static final String PREFERENCES_NAME = "auth0_user_profile";
    private static final String EMAIL = "email";
    private static final String NAME = "name";
    private static final String PICTURE_URL = "picture_url";

    public static void saveUserInfo(Context context, User userInfo) {
        SharedPreferences sp = context.getSharedPreferences(
                PREFERENCES_NAME, Context.MODE_PRIVATE);

        sp.edit()
                .putString(EMAIL, userInfo.getEmail())
                .putString(NAME, userInfo.getName())
                .putString(PICTURE_URL, userInfo.getPictureURL())
                .apply();
    }

    public static User getUserInfo(Context context) {
        SharedPreferences sp = context.getSharedPreferences(
                PREFERENCES_NAME, Context.MODE_PRIVATE);

        return new User(
                sp.getString(EMAIL, null),
                sp.getString(NAME, null),
                sp.getString(PICTURE_URL, null)
        );
    }

    public static void deleteUserInfo(Context context) {
        SharedPreferences sp = context.getSharedPreferences(
                PREFERENCES_NAME, Context.MODE_PRIVATE);

        sp.edit()
                .putString(EMAIL, null)
                .putString(NAME, null)
                .putString(PICTURE_URL, null)
                .apply();
    }
}

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Next, update the login() method in the LoginActivity to retrieve the ID Token and get the user profile from the token with the JWTDecode.Android library. Then store the user profile with the UserProfileManager.

// ...
@Override
public void onSuccess(@NonNull final Credentials credentials) {
    runOnUiThread(new Runnable() {
        @Override
        public void run() {
            Toast.makeText(LoginActivity.this, "Log In - Success", Toast.LENGTH_SHORT).show();
        }
    });

    credentialsManager.saveCredentials(credentials);
    JWT jwt = new JWT(credentials.getIdToken());
    User user = new User(
            jwt.getClaim("email").asString(),
            jwt.getClaim("name").asString(),
            jwt.getClaim("picture").asString()
    );
    UserProfileManager.saveUserInfo(LoginActivity.this, user);

    startActivity(new Intent(LoginActivity.this, TimeSheetActivity.class));
}
// ...

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4. Display UI Elements Conditionally Based on Scope

To determine whether a user has permissions to perform certain actions, we can look at the scope that was granted to the user during the authentication process. The scope will contain a string with all the scopes granted to a user, so to determine whether a particular scope was granted, we simply need to look whether the string of scopes contain the substring for that particular scope.

Store the Scope

First, we can update the User class to store the granted scopes, and then provide a helper method, hasScope() which can be used to determine whether the granted scopes contain a particular scope:

public class User {
    private String email;
    private String name;
    private String pictureURL;
    private String grantedScope;

    public User(String email, String name, String pictureURL, String grantedScope) {
        this.email = email;
        this.name = name;
        this.pictureURL = pictureURL;
        this.grantedScope = grantedScope;
    }

    public String getEmail() {
        return email;
    }

    public String getGrantedScope() { 
        return grantedScope; 
    }

    public String getName() {
        return name;
    }

    public String getPictureURL() {
        return pictureURL;
    }

    public Boolean hasScope(String scope) {
        return grantedScope.contains(scope);
    }
}

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Also remember to update the UserProfileManager to store the extra field:

public class UserProfileManager {

    private static final String PREFERENCES_NAME = "auth0_user_profile";
    private static final String EMAIL = "email";
    private static final String NAME = "name";
    private static final String PICTURE_URL = "picture_url";
    private static final String SCOPE = "scope";

    public static void saveUserInfo(Context context, User userInfo) {
        SharedPreferences sp = context.getSharedPreferences(
                PREFERENCES_NAME, Context.MODE_PRIVATE);

        sp.edit()
                .putString(EMAIL, userInfo.getEmail())
                .putString(NAME, userInfo.getName())
                .putString(PICTURE_URL, userInfo.getPictureURL())
                .putString(SCOPE, userInfo.getGrantedScope())
                .apply();
    }

    public static User getUserInfo(Context context) {
        SharedPreferences sp = context.getSharedPreferences(
                PREFERENCES_NAME, Context.MODE_PRIVATE);

        return new User(
                sp.getString(EMAIL, null),
                sp.getString(NAME, null),
                sp.getString(PICTURE_URL, null),
                sp.getString(SCOPE, null)
        );
    }

    public static void deleteUserInfo(Context context) {
        SharedPreferences sp = context.getSharedPreferences(
                PREFERENCES_NAME, Context.MODE_PRIVATE);

        sp.edit()
                .putString(EMAIL, null)
                .putString(NAME, null)
                .putString(PICTURE_URL, null)
                .putString(SCOPE, null)
                .apply();
    }
}

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Next, update the LoginActivity to pass along the scope so it can be stored in the User object:

// ...
@Override
public void onSuccess(@NonNull final Credentials credentials) {
    runOnUiThread(new Runnable() {
        @Override
        public void run() {
            Toast.makeText(LoginActivity.this, "Log In - Success", Toast.LENGTH_SHORT).show();
        }
    });

    credentialsManager.saveCredentials(credentials);
    JWT jwt = new JWT(credentials.getIdToken());
    String scopes = credentials.getScope();
    User user = new User(
            jwt.getClaim("email").asString(),
            jwt.getClaim("name").asString(),
            jwt.getClaim("picture").asString(),
            credentials.getScope()
    );
    UserProfileManager.saveUserInfo(LoginActivity.this, user);

    startActivity(new Intent(LoginActivity.this, TimeSheetActivity.class));
}
// ...

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Now, we can display certain UI elements based on whether the user was granted a particular scope. As an example, we have an approval menu item which should only be visible to users who have been granted the approve:timesheets scope.

Below you can see the code from the BaseActivity class which checks whether a user has the approve:timesheets scope, and based on that will set the visibility of the menu item which displays the approval activity:

// ...
@Override
public boolean onCreateOptionsMenu(Menu menu) {
    Boolean canApprove = UserProfileManager.getUserInfo(this).hasScope("approve:timesheets");
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.actions, menu);
    MenuItem item = menu.findItem(R.id.action_approve);
    item.setVisible(canApprove);
    return super.onCreateOptionsMenu(menu);
}
// ...

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5. Call the API

Update the Manifest

Open the app's AndroidManifest.xml and add the TimeSheetActivity:

<activity android:name="com.auth0.samples.activities.TimeSheetActivity" />

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Create the Timesheets Activity Layouts

Next create timesheet_activity.xml, the layout for the TimeSheetsActivity:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.v7.widget.Toolbar
        android:id="@+id/navToolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="?attr/colorPrimary"
        android:elevation="4dp"
        android:theme="@style/ThemeOverlay.AppCompat.ActionBar"
        app:popupTheme="@style/ThemeOverlay.AppCompat.Light"/>

    <ListView
        android:id="@+id/timesheetList"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</LinearLayout>

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The ListView widget will contain individual entries which are represented by the item_entry.xml layout:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/tvUserID"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="UserID"
        android:textStyle="bold" />
    <TextView
        android:id="@+id/tvDate"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Date" />

    <TextView
        android:id="@+id/tvProjectName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Project"
        android:textStyle="italic" />
    <TextView
        android:id="@+id/tvHours"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hours" />
</LinearLayout>

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And for the Toolbar navigation on the TimeSheetActivity, we’ll create the timesheet_action_menu.xml menu resource (/res/menu/):

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <item
        android:id="@+id/action_profile"
        android:title="Profile"
        app:showAsAction="always" />
    <item
        android:id="@+id/action_new"
        android:title="New Timesheet"
        app:showAsAction="always" />
</menu>

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Create the Timesheet Model

Create a model for working with timesheet data in our views:

package com.auth0.samples.models;

import java.util.Date;

/**
 * Created by ej on 7/9/17.
 */

public class TimeSheet {
    private String userID;
    private String projectName;
    private String date;
    private double hours;
    private int ID;

    public TimeSheet(String gUserID, String gProjectName, String gDate, double gHours, int gID) {
        this.userID = gUserID;
        this.projectName = gProjectName;
        this.date = gDate;
        this.hours = gHours;
        this.ID = gID;
    }

    public String getUserID() {
        return userID;
    }

    public String getProjectName() {
        return projectName;
    }

    public String getDateString() {
        return date;
    }

    public double getHours() {
        return hours;
    }

    public int getID() {
        return ID;
    }
}

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Create the Timesheet Adapter

The TimeSheetAdapter is a utility class which will take an array of timesheet entries and apply them to the ListView on the TimeSheetActivity.

package com.auth0.samples.utils;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;
import com.auth0.samples.R;
import com.auth0.samples.models.TimeSheet;
import java.util.ArrayList;

public class TimeSheetAdapter extends ArrayAdapter<TimeSheet> {

    public TimeSheetAdapter(Context context, ArrayList<TimeSheet> timesheets) {
        super(context, 0, timesheets);
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        TimeSheet timesheet = getItem(position);

        if (convertView == null) {
            convertView = LayoutInflater.from(getContext()).inflate(R.layout.item_entry, parent, false);
        }

        TextView tvUserID = (TextView) convertView.findViewById(R.id.tvUserID);
        TextView tvDate = (TextView) convertView.findViewById(R.id.tvDate);
        TextView tvProjectName = (TextView) convertView.findViewById(R.id.tvProjectName);
        TextView tvHours = (TextView) convertView.findViewById(R.id.tvHours);

        tvUserID.setText(timesheet.getUserID());
        tvDate.setText(timesheet.getDateString());
        tvProjectName.setText(timesheet.getProjectName());
        tvHours.setText(Double.toString(timesheet.getHours()));

        return convertView;
    }
}

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Create the Timesheet Activity

The TimeSheetActivity displays the timesheet entries for the logged in user which are stored on the server.

The @string/api_url is set to http://10.0.2.2:8080/timesheets so the Android Emulator can connect to the Node.JS API running on http://localhost:8080.
The callAPI() method retrieves timesheets from the Node.JS API.
The processResults() method takes the JSON response from callAPI() and converts it TimeSheet objects.
The onCreateOptionsMenu() and onOptionsItemSelected() methods handle the Toolbar widget navigation functionality.

package com.auth0.samples.activities;

import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.widget.ListView;
import android.widget.Toast;

import com.auth0.android.Auth0;
import com.auth0.android.authentication.AuthenticationAPIClient;
import com.auth0.android.authentication.storage.CredentialsManager;
import com.auth0.android.authentication.storage.CredentialsManagerException;
import com.auth0.android.authentication.storage.SharedPreferencesStorage;
import com.auth0.android.callback.BaseCallback;
import com.auth0.android.result.Credentials;
import com.auth0.samples.R;
import com.auth0.samples.utils.TimeSheetAdapter;
import com.auth0.samples.models.TimeSheet;
import com.squareup.okhttp.Callback;
import com.squareup.okhttp.OkHttpClient;
import com.squareup.okhttp.Request;
import com.squareup.okhttp.Response;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.IOException;
import java.util.ArrayList;

public class TimeSheetActivity extends AppCompatActivity {

    private ArrayList<TimeSheet> timesheets = new ArrayList<>();

    private String accessToken;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.timesheet_activity);
        Toolbar navToolbar = (Toolbar) findViewById(R.id.navToolbar);
        setSupportActionBar(navToolbar);

        Auth0 auth0 = new Auth0(getString(R.string.auth0_client_id), getString(R.string.auth0_domain));
        auth0.setOIDCConformant(true);

        AuthenticationAPIClient authAPIClient = new AuthenticationAPIClient(auth0);
        SharedPreferencesStorage sharedPrefStorage = new SharedPreferencesStorage(this);

        CredentialsManager credentialsManager = new CredentialsManager(authAPIClient, sharedPrefStorage);
        credentialsManager.getCredentials(new BaseCallback<Credentials, CredentialsManagerException>() {
            @Override
            public void onSuccess(Credentials payload) {
                accessToken = payload.getAccessToken();
                callAPI();
            }

            @Override
            public void onFailure(CredentialsManagerException error) {
                Toast.makeText(TimeSheetActivity.this, "Error: " + error.getMessage(), Toast.LENGTH_SHORT).show();
            }
        });
    }

    private void callAPI() {
        final Request.Builder reqBuilder = new Request.Builder()
                .get()
                .url(getString(R.string.api_url))
                .addHeader("Authorization", "Bearer " + accessToken);

        OkHttpClient client = new OkHttpClient();
        Request request = reqBuilder.build();
        client.newCall(request).enqueue(new Callback() {
            @Override
            public void onFailure(Request request, IOException e) {
                Log.e("API", "Error: ", e);
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        Toast.makeText(TimeSheetActivity.this, "An error occurred", Toast.LENGTH_SHORT).show();
                    }
                });
            }

            @Override
            public void onResponse(final Response response) throws IOException {
                timesheets = processResults(response);
                final TimeSheetAdapter adapter = new TimeSheetAdapter(TimeSheetActivity.this, timesheets);
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        if (response.isSuccessful()) {
                            ListView listView = (ListView) findViewById(R.id.timesheetList);
                            listView.setAdapter(adapter);
                            adapter.addAll(timesheets);
                        } else {
                            Toast.makeText(TimeSheetActivity.this, "API call failed.", Toast.LENGTH_SHORT).show();
                        }
                    }
                });
            }
        });
    }

    private ArrayList<TimeSheet> processResults (Response response) {
        ArrayList<TimeSheet> timesheets = new ArrayList<>();
        try {
            String jsonData = response.body().string();
            if (response.isSuccessful()) {
                JSONArray timesheetJSONArray = new JSONArray(jsonData);
                for (int i = 0; i < timesheetJSONArray.length(); i++) {
                    JSONObject timesheetJSON = timesheetJSONArray.getJSONObject(i);
                    String userID = timesheetJSON.getString("user_id");
                    String projectName = timesheetJSON.getString("project");
                    String dateStr = timesheetJSON.getString("date");
                    Double hours = timesheetJSON.getDouble("hours");
                    int id = timesheetJSON.getInt("id");

                    TimeSheet timesheet = new TimeSheet(userID, projectName, dateStr, hours, id);
                    timesheets.add(timesheet);
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        } catch (JSONException e) {
            e.printStackTrace();
        }
        return timesheets;
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.timesheet_action_menu, menu);
        return super.onCreateOptionsMenu(menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.action_new:
                startActivity(new Intent(TimeSheetActivity.this, FormActivity.class));
                break;
            case R.id.action_profile:
                startActivity(new Intent(TimeSheetActivity.this, UserActivity.class));
                break;
            default:
                return super.onOptionsItemSelected(item);
        }
        return true;
    }
}

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6. View the User Profile

To display the logged in user’s profile we’ll create the UserActivity, a corresponding user_activity.xml layout, and the user_action_menu.xml for the Toolbar navigation. The view will display the user’s name, email, and profile picture.

Update the Manifest

Open the app's AndroidManifest.xml and add the UserActivity:

<activity android:name="com.auth0.samples.activities.UserActivity" />

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Create the User Activity Layouts

Next create user_activity.xml, the layout for the UserActivity, with an ImageView for the profile picture and TextViews for the user's name and email.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.v7.widget.Toolbar
        android:id="@+id/navToolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="?attr/colorPrimary"
        android:elevation="4dp"
        android:theme="@style/ThemeOverlay.AppCompat.ActionBar"
        app:popupTheme="@style/ThemeOverlay.AppCompat.Light"/>

    <ImageView
        android:id="@+id/ivPicture"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:srcCompat="@android:color/darker_gray" />

    <TextView
        android:id="@+id/tvName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Name"
        android:textSize="24sp" />

    <TextView
        android:id="@+id/tvEmail"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Email"
        android:textSize="24sp" />
</LinearLayout>

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And create the user_actions_menu.xml for the UserActivity Toolbar:

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <item
        android:id="@+id/action_view"
        android:title="View Timesheets"
        app:showAsAction="always" />
    <item
        android:id="@+id/action_new"
        android:title="New Timesheet"
        app:showAsAction="always" />
</menu>

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Load the Profile Picture from URL

In order to load the user profile picture from the URL, create a task which extends AsyncTask and executes in the background.

package com.auth0.samples.utils;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.util.Log;
import android.widget.ImageView;

import java.io.InputStream;
import java.net.URL;

public class ImageTask extends AsyncTask<String, Void, Bitmap> {

    private ImageView bmImage;

    public ImageTask(ImageView bmImage) {
        this.bmImage = bmImage;
    }

    protected Bitmap doInBackground(String... urls) {
        String urldisplay = urls[0];
        Bitmap mIcon11 = null;

        try {
            InputStream in = new URL(urldisplay).openStream();
            mIcon11 = BitmapFactory.decodeStream(in);
        } catch (Exception e) {
            Log.e("Error", e.getMessage());
            e.printStackTrace();
        }
        return mIcon11;
    }

    protected void onPostExecute(Bitmap result) {
        bmImage.setImageBitmap(result);
    }
}

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Create the User Activity

In the onCreate() method we'll retrieve the user information from the UserProfileManager and set the values in the view. As before, the onCreateOptionsMenu() and onOptionsItemSelected() methods handle the Toolbar widget navigation functionality.

package com.auth0.samples.activities;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.widget.ImageView;
import android.widget.TextView;

import com.auth0.samples.R;
import com.auth0.samples.utils.ImageTask;
import com.auth0.samples.utils.UserProfileManager;

public class UserActivity extends AppCompatActivity {

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.user_activity);
        Toolbar navToolbar = (Toolbar) findViewById(R.id.navToolbar);
        setSupportActionBar(navToolbar);

        TextView tvName = (TextView) findViewById(R.id.tvName);
        TextView tvEmail = (TextView) findViewById(R.id.tvEmail);

        tvName.setText(UserProfileManager.getUserInfo(this).getName());
        tvEmail.setText(UserProfileManager.getUserInfo(this).getEmail());

        new ImageTask((ImageView) findViewById(R.id.ivPicture))
                .execute(UserProfileManager.getUserInfo(this).getPictureURL());

                UserProfileManager.getUserInfo(this).getName();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu items for use in the action bar
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.user_action_menu, menu);
        return super.onCreateOptionsMenu(menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.action_new:
                startActivity(new Intent(UserActivity.this, FormActivity.class));
                break;
            case R.id.action_view:
                startActivity(new Intent(UserActivity.this, TimeSheetActivity.class));
                break;
            default:
                // If we got here, the user's action was not recognized.
                // Invoke the superclass to handle it.
                return super.onOptionsItemSelected(item);

        }
        return true;
    }
}

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7. Form for New Timesheets

Next create the FormActivity and layout to handle creating new timesheet entries.

Update the Manifest

Open the app's AndroidManifest.xml and add the FormActivity:

<activity android:name="com.auth0.samples.activities.FormActivity" />

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Create the Form Activity Layouts

Create the form_activity.xml layout with EditText for the project name and hours worked inputs, and a DatePicker for the day worked.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/mainForm"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:weightSum="1">

    <android.support.v7.widget.Toolbar
        android:id="@+id/navToolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="?attr/colorPrimary"
        android:elevation="4dp"
        android:theme="@style/ThemeOverlay.AppCompat.ActionBar"
        app:popupTheme="@style/ThemeOverlay.AppCompat.Light"/>

    <EditText
        android:id="@+id/editProjectName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10"
        android:hint="Project Name"
        android:inputType="textPersonName" />

    <EditText
        android:id="@+id/editHours"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10"
        android:hint="Hours Worked"
        android:inputType="number|numberDecimal" />

    <DatePicker
        android:id="@+id/datePicker"
        android:layout_width="match_parent"
        android:layout_height="191dp"
        android:layout_weight="0.93" />

    <Button
        android:id="@+id/submitTimeSheetButton"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Submit" />
</LinearLayout>

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And create the form_actions_menu.xml for the FormActivity Toolbar:

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <item
        android:id="@+id/action_profile"
        android:title="Profile"
        app:showAsAction="always" />
    <item
        android:id="@+id/action_view"
        android:title="View Timesheets"
        app:showAsAction="always" />
</menu>

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Create the Form Activity

The @string/api_url is set to http://10.0.2.2:8080/timesheets so the Android Emulator can connect to the Node.JS API running on http://localhost:8080.
The onCreate() method initializes the form and collects the input for the postAPI() method when the submit button is pressed.
The postAPI() method will send the user input retrieved from the form to the Node.JS API in JSON format.
The clearForm() method clears the input forms.
The onCreateOptionsMenu() and onOptionsItemSelected() methods handle the Toolbar widget navigation functionality.

package com.auth0.samples.activities;

import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.DatePicker;
import android.widget.EditText;
import android.widget.Toast;

import com.auth0.android.Auth0;
import com.auth0.android.authentication.AuthenticationAPIClient;
import com.auth0.android.authentication.storage.CredentialsManager;
import com.auth0.android.authentication.storage.CredentialsManagerException;
import com.auth0.android.authentication.storage.SharedPreferencesStorage;
import com.auth0.android.callback.BaseCallback;
import com.auth0.android.result.Credentials;
import com.auth0.samples.R;
import com.squareup.okhttp.Callback;
import com.squareup.okhttp.MediaType;
import com.squareup.okhttp.OkHttpClient;
import com.squareup.okhttp.Request;
import com.squareup.okhttp.RequestBody;
import com.squareup.okhttp.Response;

import org.json.JSONException;
import org.json.JSONObject;

import java.io.IOException;
import java.util.Calendar;
import java.util.Date;

public class FormActivity extends AppCompatActivity {

    private static final MediaType MEDIA_TYPE_JSON = MediaType.parse("application/json; charset=utf-8");

    private String accessToken;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.form_activity);
        Toolbar navToolbar = (Toolbar) findViewById(R.id.navToolbar);
        setSupportActionBar(navToolbar);

        Auth0 auth0 = new Auth0(getString(R.string.auth0_client_id), getString(R.string.auth0_domain));
        auth0.setOIDCConformant(true);

        AuthenticationAPIClient authAPIClient = new AuthenticationAPIClient(auth0);
        SharedPreferencesStorage sharedPrefStorage = new SharedPreferencesStorage(this);

        CredentialsManager credentialsManager = new CredentialsManager(authAPIClient, sharedPrefStorage);
        credentialsManager.getCredentials(new BaseCallback<Credentials, CredentialsManagerException>() {
            @Override
            public void onSuccess(Credentials payload) {
                accessToken = payload.getAccessToken();
            }

            @Override
            public void onFailure(CredentialsManagerException error) {
                Toast.makeText(FormActivity.this, "Error: " + error.getMessage(), Toast.LENGTH_SHORT).show();
            }
        });

        Button submitTimeSheetButton = (Button) findViewById(R.id.submitTimeSheetButton);
        final EditText editProjectName = (EditText) findViewById(R.id.editProjectName);
        final EditText editHours = (EditText) findViewById(R.id.editHours);
        final DatePicker datePicker = (DatePicker) findViewById(R.id.datePicker);

        submitTimeSheetButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                int day = datePicker.getDayOfMonth();
                int month = datePicker.getMonth();
                int year =  datePicker.getYear();

                Calendar calendar = Calendar.getInstance();
                calendar.set(year, month, day);

                postAPI(
                        editProjectName.getText().toString(),
                        calendar.getTime(),
                        editHours.getText().toString()
                );
            }
        });
    }

    private void postAPI(String projectName, Date date, String hours) {

        JSONObject postBody = new JSONObject();
        try {
            postBody.put("project", projectName);
        } catch (JSONException e) {
            e.printStackTrace();
        }
        try {
            postBody.put("date", date);
        } catch (JSONException e) {
            e.printStackTrace();
        }
        try {
            postBody.put("hours", hours);
        } catch (JSONException e) {
            e.printStackTrace();
        }
        String postStr = postBody.toString();

        final Request.Builder reqBuilder = new Request.Builder()
                .post(RequestBody.create(MEDIA_TYPE_JSON, postStr))
                .url(getString(R.string.api_url))
                .addHeader("Authorization", "Bearer " + accessToken);

        OkHttpClient client = new OkHttpClient();
        Request request = reqBuilder.build();

        client.newCall(request).enqueue(new Callback() {
            @Override
            public void onFailure(Request request, IOException e) {
                Log.e("API", "Error: ", e);
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        Toast.makeText(FormActivity.this, "An error occurred", Toast.LENGTH_SHORT).show();
                    }
                });
            }

            @Override
            public void onResponse(final Response response) throws IOException {
                final String resBody = response.body().string();

                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        if (response.isSuccessful()) {
                            clearForm((ViewGroup) findViewById(R.id.mainForm));
                            Intent intent = new Intent(FormActivity.this, TimeSheetActivity.class);
                            FormActivity.this.startActivity(intent);
                        } else {
                            Toast.makeText(FormActivity.this, "Timesheet creation failed.", Toast.LENGTH_SHORT).show();
                        }
                    }
                });
            }
        });
    }

    private void clearForm(ViewGroup group) {
        for (int i = 0, count = group.getChildCount(); i < count; ++i) {
            View view = group.getChildAt(i);
            if (view instanceof EditText) {
                ((EditText)view).setText("");
            }

            if(view instanceof ViewGroup && (((ViewGroup)view).getChildCount() > 0))
                clearForm((ViewGroup)view);
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.form_action_menu, menu);
        return super.onCreateOptionsMenu(menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.action_view:
                startActivity(new Intent(FormActivity.this, TimeSheetActivity.class));
                break;
            case R.id.action_profile:
                startActivity(new Intent(FormActivity.this, UserActivity.class));
                break;
            default:
                return super.onOptionsItemSelected(item);

        }
        return true;
    }
}

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Test the App

Before continuing, ensure you have implemented the Node.JS API.

Start the API by navigating to the API's directory in your terminal and entering the node server command.
Open the mobile app in Android Studio and press the Run button.
Select the Nexus 5X API 23 virtual device.
Once the emulator has loaded the mobile app, you can login user then, create and view timesheet entries from the running Node.JS API.

That's it! You are done!

Get Started

Android Mobile Application Implementation (Mobile Apps + API)

1. Set Up the Application

Sample Project

Set the Dependencies

Update the Manifest

Set Configuration Values

2. Authorize the User

Update the Manifest

Store the Credentials

3. Get the User Profile

Create the User Model

Store the User Profile

4. Display UI Elements Conditionally Based on Scope

Store the Scope

Display Approval Menu Based on Scope

5. Call the API

Update the Manifest

Create the Timesheets Activity Layouts

Create the Timesheet Model

Create the Timesheet Adapter

Create the Timesheet Activity

6. View the User Profile

Update the Manifest

Create the User Activity Layouts

Load the Profile Picture from URL

Create the User Activity

7. Form for New Timesheets

Update the Manifest

Create the Form Activity Layouts

Create the Form Activity

Test the App

Get Started

Android Mobile Application Implementation (Mobile Apps + API)

1. Set Up the Application

Sample Project

Set the Dependencies

Update the Manifest

Set Configuration Values

2. Authorize the User

Update the Manifest

Create the Login Activity

Store the Credentials

3. Get the User Profile

Create the User Model

Store the User Profile

4. Display UI Elements Conditionally Based on Scope

Store the Scope

Display Approval Menu Based on Scope

5. Call the API

Update the Manifest

Create the Timesheets Activity Layouts

Create the Timesheet Model

Create the Timesheet Adapter

Create the Timesheet Activity

6. View the User Profile

Update the Manifest

Create the User Activity Layouts

Load the Profile Picture from URL

Create the User Activity

7. Form for New Timesheets

Update the Manifest

Create the Form Activity Layouts

Create the Form Activity

Test the App