Add PMD settings

app/quality.gradle

@@ -1,6 +1,7 @@
 apply plugin: 'checkstyle'
+apply plugin: 'pmd'
 
-check.dependsOn 'checkstyle'
+check.dependsOn 'checkstyle', 'pmd'
 
 checkstyle {
     toolVersion = '7.5.1'
@@ -17,7 +18,28 @@ task checkstyle(type: Checkstyle) {
     reports {
         html {
             enabled true
-            destination "$project.buildDir/reports/checkstyle/checkstyle.html"
+            destination "${project.buildDir}/reports/checkstyle/checkstyle.html"
+        }
+    }
+}
+
+task pmd(type: Pmd) {
+    ignoreFailures = true
+    ruleSetFiles = files("${project.rootDir}/ruleset.xml")
+    ruleSets = []
+
+    source 'src'
+    include '**/*.java'
+    exclude '**/gen/**'
+
+    reports {
+        xml.enabled = false
+        html.enabled = true
+        xml {
+            destination "${project.buildDir}/reports/pmd/pmd.xml"
+        }
+        html {
+            destination "${project.buildDir}/reports/pmd/pmd.html"
         }
     }
 }

ruleset.xml

@@ -0,0 +1,14 @@
+<?xml version="1.0"?>
+<ruleset xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" name="Commons Android App Rules"
+    xmlns="http://pmd.sf.net/ruleset/1.0.0"
+    xsi:noNamespaceSchemaLocation="http://pmd.sf.net/ruleset_xml_schema.xsd"
+    xsi:schemaLocation="http://pmd.sf.net/ruleset/1.0.0 http://pmd.sf.net/ruleset_xml_schema.xsd">
+
+    <description>Custom ruleset for Commons Android app</description>
+
+    <exclude-pattern>.*/R.java</exclude-pattern>
+    <exclude-pattern>.*/gen/.*</exclude-pattern>
+
+    <rule ref="rulesets/java/android.xml" />
+    <rule ref="rulesets/java/basic.xml" />
+</ruleset>