Issue 4248 - Add codestyle check

libadblockplus-android-tests/build.xml

 <?xml version="1.0" encoding="UTF-8"?>
 <project name="Adblock Plus Library Tests" default="help">
 
     <!-- The local.properties file is created and updated by the 'android' tool.
          It contains the path to the SDK. It should *NOT* be checked into
          Version Control Systems. -->
     <property file="local.properties" />
 
     <!-- The ant.properties file can be created by you. It is only edited by the
          'android' tool to add properties to it.
@@ skipping 71 matching lines @@
 
          ***********************
          ****** IMPORTANT ******
          ***********************
          In all cases you must update the value of version-tag below to read 'custom' instead of an integer,
          in order to avoid having your file be overridden by tools such as "android update project"
     -->
     <!-- version-tag: 1 -->
     <import file="${sdk.dir}/tools/ant/build.xml" />
 
+    <!-- checkstyle target for java code -->
+    <target name="checkstyle"
+        description="Generates a report of code convention violations.">
+
+        <taskdef
+            resource="com/puppycrawl/tools/checkstyle/ant/checkstyle-ant-task.properties"
+            classpath="../third_party/checkstyle/java/lib/checkstyle-6.19-all.jar"/>
+    
+        <property
+            name="checkstyle.header.file"
+            value="../third_party/checkstyle/java/res/header.txt"/>
+
+        <checkstyle
+            config="../third_party/checkstyle/java/rules/eyeo_checks.xml"
+            failOnViolation="true">
+            <fileset dir="src" includes="**/*.java"/>
+            <formatter type="plain"/>
+        </checkstyle>
+
+    </target>
+
     <!-- custom test target to perform specific test/method only -->
     <target
         name="testOnly"
         depends="-test-project-check"
         description="Runs a single test case, given with -DtestClass=package.path.to.Class">
 
         <property name="test.runner" value="android.test.InstrumentationTestRunner" />
         <property name="tested.project.absolute.dir" location="${tested.project.dir}" />
 
         <!-- Application package of the tested project extracted from its manifest file -->
         <xpath
             input="${tested.project.absolute.dir}/AndroidManifest.xml"
             expression="/manifest/@package"
             output="tested.project.app.package" />
 
         <run-tests-helper>
             <extra-instrument-args>
                 <arg value="-e" />
                   <arg value="class" />
                   <arg value="${testClass}" />
             </extra-instrument-args>
         </run-tests-helper>
     </target>
 
 </project>