update travis ci
diff --git a/.travis.yml b/.travis.yml
index 7d06826..414bb88 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,8 +5,11 @@
     - oraclejdk8
     - oraclejdk11
 
-before_install:
-    - ./mvnw checkstyle:check
+cache:
+  directories:
+    - $HOME/.m2
+
+install: true
 
 script:
     - travis_wait 30 ./mvnw clean install -DskipTests=false -Dcheckstyle.skip=false -Dmaven.javadoc.skip=true