update travis

.travis.yml

@@ -10,13 +10,19 @@ sudo: false
 android:
   components:
     - tools
+    - platform-tools
     - build-tools-27.0.3
     - android-27
-    - extra-android-m2repository
-    - extra-android-support
+
+before_cache:
+  - rm -f $HOME/.gradle/caches/modules-2/modules-2.lock
+cache:
+  directories:
+    - $HOME/.gradle/caches/
+    - $HOME/.gradle/wrapper/
 
 before_install:
- - chmod +x gradlew
+  - yes | sdkmanager 'platforms;android-27'
 
 script:
   - ./gradlew assembleRelease

example/build.gradle

@@ -23,7 +23,11 @@ dependencies {
     implementation fileTree(include: ['*.jar'], dir: 'libs')
     testImplementation 'junit:junit:4.12'
 
+    implementation 'com.android.support:appcompat-v7:27.1.1'
+    implementation 'com.android.support:recyclerview-v7:27.1.1'
+
     implementation 'com.nineoldandroids:library:2.4.0'
+
     implementation 'com.github.bumptech.glide:glide:3.7.0'
     implementation 'me.iwf.photopicker:PhotoPicker:0.9.5@aar'
 

example/src/main/java/top/zibin/luban/example/MainActivity.java

@@ -36,11 +36,11 @@ public class MainActivity extends AppCompatActivity {
     super.onCreate(savedInstanceState);
     setContentView(R.layout.activity_main);
 
-    RecyclerView mRecyclerView = (RecyclerView) findViewById(R.id.recycler_view);
+    RecyclerView mRecyclerView = findViewById(R.id.recycler_view);
     mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
     mRecyclerView.setAdapter(mAdapter);
 
-    Button fab = (Button) findViewById(R.id.fab);
+    Button fab = findViewById(R.id.fab);
     fab.setOnClickListener(new View.OnClickListener() {
       @Override
       public void onClick(View view) {