diff --git a/app/build.gradle b/app/build.gradle
index b69e3b6..ea195c2 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -3,13 +3,13 @@ apply plugin: 'com.android.application'
 apply plugin: 'realm-android'
 
 android {
-    compileSdkVersion 25
-    buildToolsVersion "25.0.2"
+    compileSdkVersion 'android-O'
+    buildToolsVersion '26.0.0 rc2'
 
     defaultConfig {
         applicationId "io.github.marktony.espresso"
         minSdkVersion 21
-        targetSdkVersion 25
+        targetSdkVersion 26
         versionCode 1
         versionName "1.0"
         testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
@@ -31,35 +31,10 @@ android {
         abortOnError false
     }
 
-    productFlavors {
-        mock {
-            applicationIdSuffix = ".mock"
-        }
-        prod {
-
-        }
-    }
-
-    // Remove mockRelease as it's not needed.
-    android.variantFilter { variant ->
-        if (variant.buildType.name == 'release'
-                && variant.getFlavors().get(0).name == 'mock') {
-            variant.setIgnore(true);
-        }
-    }
-
-    // Always show the result of every unit test, even if it passes.
-    testOptions.unitTests.all {
-        testLogging {
-            events 'passed', 'skipped', 'failed', 'standardOut', 'standardError'
-        }
-    }
-
-    sourceSets { prod { java.srcDirs = ['src/prod/java', 'src/prod/java/'] } }
 }
 
 ext {
-    supportLibVersion = '25.3.1'
+    supportLibVersion = '26.0.0-beta1'
     rxjavaVersion = '2.0.1'
     retrofitVersion = '2.2.0'
     zxingLibVersion = '3.3.0'
@@ -92,15 +67,15 @@ dependencies {
     // Zxing
     compile "com.google.zxing:core:$zxingLibVersion"
     // Material date time picker
-    compile "com.wdullaer:materialdatetimepicker:$datetimePickerVersion"
+    compile("com.wdullaer:materialdatetimepicker:$datetimePickerVersion"){
+        exclude group:'com.android.support'
+    }
     // CircleImageView
-    compile "de.hdodenhof:circleimageview:$circleimageviewVersion"
+    compile("de.hdodenhof:circleimageview:$circleimageviewVersion"){
+        exclude group:'com.android.support'
+    }
 
     testCompile "junit:junit:$junitVersion"
-    testCompile "org.mockito:mockito-all:$mockitoVersion"
-
-    // Mockito
-    androidTestCompile "org.mockito:mockito-core:$mockitoVersion"
 
     // Espresso
     androidTestCompile "com.android.support:support-annotations:$supportLibVersion"
diff --git a/app/src/androidTest/java/io/github/marktony/espresso/packages/PackagesScreenTest.java b/app/src/androidTest/java/io/github/marktony/espresso/packages/PackagesScreenTest.java
index beca415..da9dce2 100644
--- a/app/src/androidTest/java/io/github/marktony/espresso/packages/PackagesScreenTest.java
+++ b/app/src/androidTest/java/io/github/marktony/espresso/packages/PackagesScreenTest.java
@@ -24,6 +24,7 @@
 
 /**
  * Created by lizhaotailang on 2017/5/12.
+ * The tests for {@link io.github.marktony.espresso.mvp.packages.PackagesFragment}.
  */
 
 @RunWith(AndroidJUnit4.class)
diff --git a/app/src/androidTest/java/io/github/marktony/espresso/settings/SettingsScreenTest.java b/app/src/androidTest/java/io/github/marktony/espresso/settings/SettingsScreenTest.java
index cb40f27..ee17c75 100644
--- a/app/src/androidTest/java/io/github/marktony/espresso/settings/SettingsScreenTest.java
+++ b/app/src/androidTest/java/io/github/marktony/espresso/settings/SettingsScreenTest.java
@@ -24,6 +24,7 @@
 
 /**
  * Created by lizhaotailang on 2017/5/14.
+ * The tests for {@link io.github.marktony.espresso.ui.SettingsFragment}.
  */
 
 @RunWith(AndroidJUnit4.class)
diff --git a/app/src/main/java/io/github/marktony/espresso/mvp/addpackage/AddPackageFragment.java b/app/src/main/java/io/github/marktony/espresso/mvp/addpackage/AddPackageFragment.java
index 3abacf1..634223f 100644
--- a/app/src/main/java/io/github/marktony/espresso/mvp/addpackage/AddPackageFragment.java
+++ b/app/src/main/java/io/github/marktony/espresso/mvp/addpackage/AddPackageFragment.java
@@ -212,12 +212,12 @@ public void initViews(View view) {
         activity.setSupportActionBar((Toolbar) view.findViewById(R.id.toolbar));
         activity.getSupportActionBar().setDisplayHomeAsUpEnabled(true);
 
-        editTextName = (TextInputEditText) view.findViewById(R.id.editTextName);
-        editTextNumber = (TextInputEditText) view.findViewById(R.id.editTextNumber);
-        textViewScanCode = (AppCompatTextView) view.findViewById(R.id.textViewScanCode);
-        fab = (FloatingActionButton) view.findViewById(R.id.fab);
-        progressBar = (ProgressBar) view.findViewById(R.id.progressBar);
-        scrollView = (NestedScrollView) view.findViewById(R.id.scrollView);
+        editTextName = view.findViewById(R.id.editTextName);
+        editTextNumber = view.findViewById(R.id.editTextNumber);
+        textViewScanCode = view.findViewById(R.id.textViewScanCode);
+        fab = view.findViewById(R.id.fab);
+        progressBar = view.findViewById(R.id.progressBar);
+        scrollView = view.findViewById(R.id.scrollView);
 
     }
 
diff --git a/app/src/main/java/io/github/marktony/espresso/mvp/companies/CompaniesFragment.java b/app/src/main/java/io/github/marktony/espresso/mvp/companies/CompaniesFragment.java
index 9ee5be3..1e01261 100644
--- a/app/src/main/java/io/github/marktony/espresso/mvp/companies/CompaniesFragment.java
+++ b/app/src/main/java/io/github/marktony/espresso/mvp/companies/CompaniesFragment.java
@@ -103,7 +103,7 @@ public boolean onOptionsItemSelected(MenuItem item) {
 
     @Override
     public void initViews(View view) {
-        recyclerView = (RecyclerView) view.findViewById(R.id.recyclerViewCompaniesList);
+        recyclerView = view.findViewById(R.id.recyclerViewCompaniesList);
         final LinearLayoutManager layoutManager = new LinearLayoutManager(getContext());
         recyclerView.setLayoutManager(layoutManager);
     }
diff --git a/app/src/main/java/io/github/marktony/espresso/mvp/companydetails/CompanyDetailFragment.java b/app/src/main/java/io/github/marktony/espresso/mvp/companydetails/CompanyDetailFragment.java
index a37543b..928f815 100644
--- a/app/src/main/java/io/github/marktony/espresso/mvp/companydetails/CompanyDetailFragment.java
+++ b/app/src/main/java/io/github/marktony/espresso/mvp/companydetails/CompanyDetailFragment.java
@@ -136,10 +136,10 @@ public void initViews(View view) {
         activity.setSupportActionBar((Toolbar) view.findViewById(R.id.toolbar));
         activity.getSupportActionBar().setDisplayHomeAsUpEnabled(true);
 
-        fab = (FloatingActionButton) view.findViewById(R.id.fab);
-        textViewCompanyName = (AppCompatTextView) view.findViewById(R.id.textViewCompany);
-        textViewTel = (AppCompatTextView) view.findViewById(R.id.textViewCompanyPhoneNumber);
-        textViewWebsite = (AppCompatTextView) view.findViewById(R.id.textViewCompanyWebsite);
+        fab = view.findViewById(R.id.fab);
+        textViewCompanyName = view.findViewById(R.id.textViewCompany);
+        textViewTel = view.findViewById(R.id.textViewCompanyPhoneNumber);
+        textViewWebsite = view.findViewById(R.id.textViewCompanyWebsite);
     }
 
     @Override
diff --git a/app/src/main/java/io/github/marktony/espresso/mvp/packagedetails/PackageDetailsFragment.java b/app/src/main/java/io/github/marktony/espresso/mvp/packagedetails/PackageDetailsFragment.java
index cea7254..86ed830 100644
--- a/app/src/main/java/io/github/marktony/espresso/mvp/packagedetails/PackageDetailsFragment.java
+++ b/app/src/main/java/io/github/marktony/espresso/mvp/packagedetails/PackageDetailsFragment.java
@@ -166,12 +166,12 @@ public void initViews(View view) {
         activity.setSupportActionBar((Toolbar) view.findViewById(R.id.toolbar));
         activity.getSupportActionBar().setDisplayHomeAsUpEnabled(true);
 
-        recyclerView = (RecyclerView) view.findViewById(R.id.recyclerView);
+        recyclerView = view.findViewById(R.id.recyclerView);
         recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
-        fab = (FloatingActionButton) view.findViewById(R.id.fab);
-        swipeRefreshLayout = (SwipeRefreshLayout) view.findViewById(R.id.swipeRefreshLayout);
+        fab = view.findViewById(R.id.fab);
+        swipeRefreshLayout = view.findViewById(R.id.swipeRefreshLayout);
         swipeRefreshLayout.setColorSchemeColors(ContextCompat.getColor(getContext(), R.color.colorPrimary));
-        toolbarLayout = (CollapsingToolbarLayout) view.findViewById(R.id.toolbar_layout);
+        toolbarLayout = view.findViewById(R.id.toolbar_layout);
 
     }
 
diff --git a/app/src/main/java/io/github/marktony/espresso/mvp/packages/MainActivity.java b/app/src/main/java/io/github/marktony/espresso/mvp/packages/MainActivity.java
index 36e87e8..b3c56c5 100644
--- a/app/src/main/java/io/github/marktony/espresso/mvp/packages/MainActivity.java
+++ b/app/src/main/java/io/github/marktony/espresso/mvp/packages/MainActivity.java
@@ -228,7 +228,7 @@ public void onDrawerStateChanged(int newState) {
 
         }
 
-        drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
+        drawer = findViewById(R.id.drawer_layout);
         drawer.closeDrawer(GravityCompat.START);
         return true;
     }
@@ -261,10 +261,10 @@ protected void onSaveInstanceState(Bundle outState) {
      */
     private void initViews() {
 
-        toolbar = (Toolbar) findViewById(R.id.toolbar);
+        toolbar = findViewById(R.id.toolbar);
         setSupportActionBar(toolbar);
 
-        drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
+        drawer = findViewById(R.id.drawer_layout);
         ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                 this, drawer, toolbar,
                 R.string.navigation_drawer_open,
@@ -273,7 +273,7 @@ private void initViews() {
         drawer.setDrawerListener(toggle);
         toggle.syncState();
 
-        navigationView = (NavigationView) findViewById(R.id.nav_view);
+        navigationView = findViewById(R.id.nav_view);
         navigationView.setNavigationItemSelectedListener(this);
 
     }
diff --git a/app/src/main/java/io/github/marktony/espresso/mvp/packages/PackagesFragment.java b/app/src/main/java/io/github/marktony/espresso/mvp/packages/PackagesFragment.java
index 1627850..142b32d 100644
--- a/app/src/main/java/io/github/marktony/espresso/mvp/packages/PackagesFragment.java
+++ b/app/src/main/java/io/github/marktony/espresso/mvp/packages/PackagesFragment.java
@@ -201,12 +201,12 @@ public boolean onContextItemSelected(MenuItem item) {
     @Override
     public void initViews(View view) {
 
-        fab = (FloatingActionButton) view.findViewById(R.id.fab);
-        bottomNavigationView = (BottomNavigationView) view.findViewById(R.id.bottomNavigationView);
-        emptyView = (LinearLayout) view.findViewById(R.id.emptyView);
-        recyclerView = (RecyclerView) view.findViewById(R.id.recyclerView);
+        fab =  view.findViewById(R.id.fab);
+        bottomNavigationView = view.findViewById(R.id.bottomNavigationView);
+        emptyView =  view.findViewById(R.id.emptyView);
+        recyclerView =  view.findViewById(R.id.recyclerView);
         recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
-        refreshLayout = (SwipeRefreshLayout) view.findViewById(R.id.refreshLayout);
+        refreshLayout =  view.findViewById(R.id.refreshLayout);
         refreshLayout.setColorSchemeColors(ContextCompat.getColor(getContext(), R.color.colorPrimary));
 
         // ItemTouchHelper helps to handle the drag or swipe action.
diff --git a/app/src/main/java/io/github/marktony/espresso/mvp/search/SearchFragment.java b/app/src/main/java/io/github/marktony/espresso/mvp/search/SearchFragment.java
index b5acaa1..90395e5 100644
--- a/app/src/main/java/io/github/marktony/espresso/mvp/search/SearchFragment.java
+++ b/app/src/main/java/io/github/marktony/espresso/mvp/search/SearchFragment.java
@@ -119,9 +119,9 @@ public void initViews(View view) {
         activity.setSupportActionBar((Toolbar) view.findViewById(R.id.toolbar));
         activity.getSupportActionBar().setDisplayHomeAsUpEnabled(true);
 
-        searchView = (SearchView) view.findViewById(R.id.searchView);
+        searchView = view.findViewById(R.id.searchView);
         searchView.setIconified(false);
-        recyclerView = (RecyclerView) view.findViewById(R.id.recyclerView);
+        recyclerView = view.findViewById(R.id.recyclerView);
         recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
     }
 
diff --git a/app/src/main/java/io/github/marktony/espresso/ui/LicensesFragment.java b/app/src/main/java/io/github/marktony/espresso/ui/LicensesFragment.java
index 3c04085..137cc0f 100644
--- a/app/src/main/java/io/github/marktony/espresso/ui/LicensesFragment.java
+++ b/app/src/main/java/io/github/marktony/espresso/ui/LicensesFragment.java
@@ -43,7 +43,7 @@ public void onCreate(@Nullable Bundle savedInstanceState) {
     public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
         View view = inflater.inflate(R.layout.fragment_licenses, container, false);
 
-        WebView webView = (WebView) view.findViewById(R.id.webView);
+        WebView webView = view.findViewById(R.id.webView);
         webView.loadUrl("file:///android_asset/license.html");
 
         return view;
diff --git a/app/src/main/java/io/github/marktony/espresso/ui/onboarding/OnboardingActivity.java b/app/src/main/java/io/github/marktony/espresso/ui/onboarding/OnboardingActivity.java
index 90db507..502a207 100644
--- a/app/src/main/java/io/github/marktony/espresso/ui/onboarding/OnboardingActivity.java
+++ b/app/src/main/java/io/github/marktony/espresso/ui/onboarding/OnboardingActivity.java
@@ -61,6 +61,8 @@ public class OnboardingActivity extends AppCompatActivity {
 
     private static final int MSG_DATA_INSERT_FINISH = 1;
 
+    private Handler handler = new Handler(new HandlerCallback());
+
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
@@ -138,16 +140,17 @@ public void onClick(View v) {
 
     private void initViews() {
         OnboardingPagerAdapter pagerAdapter = new OnboardingPagerAdapter(getSupportFragmentManager());
-        viewPager = (ViewPager) findViewById(R.id.view_pager);
+        viewPager = findViewById(R.id.view_pager);
         viewPager.setAdapter(pagerAdapter);
-        buttonFinish = (AppCompatButton) findViewById(R.id.buttonFinish);
+        buttonFinish = findViewById(R.id.buttonFinish);
         buttonFinish.setText(R.string.onboarding_finish_button_description_wait);
         buttonFinish.setEnabled(false);
-        buttonNext = (ImageButton) findViewById(R.id.imageButtonNext);
-        buttonPre = (ImageButton) findViewById(R.id.imageButtonPre);
-        indicators = new ImageView[] {(ImageView) findViewById(R.id.imageViewIndicator0),
-                (ImageView) findViewById(R.id.imageViewIndicator1),
-                (ImageView) findViewById(R.id.imageViewIndicator2)};
+        buttonNext = findViewById(R.id.imageButtonNext);
+        buttonPre = findViewById(R.id.imageButtonPre);
+        indicators = new ImageView[] {
+                findViewById(R.id.imageViewIndicator0),
+                findViewById(R.id.imageViewIndicator1),
+                findViewById(R.id.imageViewIndicator2) };
     }
 
     private void initData() {
@@ -164,17 +167,20 @@ private void updateIndicators(int position) {
         }
     }
 
-    private Handler handler = new Handler() {
+    private class HandlerCallback implements Handler.Callback {
+
         @Override
-        public void handleMessage(Message msg) {
-            switch (msg.what) {
+        public boolean handleMessage(Message message) {
+            switch (message.what) {
                 case MSG_DATA_INSERT_FINISH:
+
                     buttonFinish.setText(R.string.onboarding_finish_button_description);
                     buttonFinish.setEnabled(true);
                     break;
             }
+            return true;
         }
-    };
+    }
 
     private class InitCompaniesDataTask extends AsyncTask<Void, Void, Void> {
 
diff --git a/app/src/main/java/io/github/marktony/espresso/ui/onboarding/OnboardingFragment.java b/app/src/main/java/io/github/marktony/espresso/ui/onboarding/OnboardingFragment.java
index 8bb1ea0..52a2d86 100644
--- a/app/src/main/java/io/github/marktony/espresso/ui/onboarding/OnboardingFragment.java
+++ b/app/src/main/java/io/github/marktony/espresso/ui/onboarding/OnboardingFragment.java
@@ -89,9 +89,9 @@ public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle sa
     }
 
     private void initViews(View view) {
-        sectionLabel = (AppCompatTextView) view.findViewById(R.id.section_label);
-        sectionIntro = (AppCompatTextView) view.findViewById(R.id.section_intro);
-        sectionImg = (ImageView) view.findViewById(R.id.section_img);
+        sectionLabel = view.findViewById(R.id.section_label);
+        sectionIntro = view.findViewById(R.id.section_intro);
+        sectionImg = view.findViewById(R.id.section_img);
     }
 
 }
diff --git a/app/src/prod/java/io/github/marktony/espresso/Injection.java b/app/src/prod/java/io/github/marktony/espresso/Injection.java
deleted file mode 100644
index fdf8c27..0000000
--- a/app/src/prod/java/io/github/marktony/espresso/Injection.java
+++ /dev/null
@@ -1,25 +0,0 @@
-package io.github.marktony.espresso;
-
-import android.content.Context;
-import android.support.annotation.NonNull;
-
-import io.github.marktony.espresso.data.source.PackagesRepository;
-import io.github.marktony.espresso.data.source.local.PackagesLocalDataSource;
-import io.github.marktony.espresso.data.source.remote.PackagesRemoteDataSource;
-
-/**
- * Created by lizhaotailang on 2017/5/14.
- * Enables injection of production implementations for
- * {@link PackagesRepository} at compile time.
- */
-
-public class Injection {
-
-    public static PackagesRepository providePackagesRepository(@NonNull Context context) {
-        return PackagesRepository.getInstance(
-                PackagesRemoteDataSource.getInstance(),
-                PackagesLocalDataSource.getInstance()
-        );
-    }
-
-}
diff --git a/build.gradle b/build.gradle
index dfb47b3..4126c15 100644
--- a/build.gradle
+++ b/build.gradle
@@ -2,13 +2,14 @@
 
 buildscript {
     repositories {
+        maven { url 'https://maven.google.com' }
         jcenter()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:2.3.1'
+        classpath 'com.android.tools.build:gradle:3.0.0-alpha1'
 
         // Realm database
-        classpath "io.realm:realm-gradle-plugin:3.0.0"
+        classpath "io.realm:realm-gradle-plugin:3.2.1"
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files
     }
@@ -17,6 +18,7 @@ buildscript {
 allprojects {
     repositories {
         jcenter()
+        maven { url 'https://maven.google.com' }
     }
 }
 
diff --git a/gradle.properties b/gradle.properties
index aac7c9b..ede038c 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -9,7 +9,7 @@
 
 # Specifies the JVM arguments used for the daemon process.
 # The setting is particularly useful for tweaking memory settings.
-org.gradle.jvmargs=-Xmx1536m
+org.gradle.jvmargs=-Xmx1000m
 
 # When configured, Gradle will run in incubating parallel mode.
 # This option should only be used with decoupled projects. More details, visit
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index dc28a0a..8b71aca 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -3,4 +3,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-3.3-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.0-milestone-1-all.zip