Travis CI cache

.travis.yml

@@ -1,5 +1,26 @@
 language: android
 
+jdk:
+  - oraclejdk8
+
+before_cache:
+  # Do not cache a few Gradle files/directories (see https://docs.travis-ci.com/user/languages/java/#Caching)
+  - rm -f  $HOME/.gradle/caches/modules-2/modules-2.lock
+  - rm -fr $HOME/.gradle/caches/*/plugin-resolution/
+
+cache:
+  directories:
+    # Android SDK
+    - $HOME/android-sdk-dl
+    - $HOME/android-sdk
+
+    # Gradle dependencies
+    - $HOME/.gradle/caches/
+    - $HOME/.gradle/wrapper/
+
+    # Android build cache (see http://tools.android.com/tech-docs/build-cache)
+    - $HOME/.android/build-cache
+
 android:
   components:
     - tools
@@ -10,10 +31,9 @@ android:
 
     - extra-android-m2repository
 
+env:
+  - ANDROID_HOME=$HOME/android-sdk
+
 script:
    - ./gradlew build connectedCheck
 
-sudo: false
-
-jdk:
-  - oraclejdk8