diff --git a/gerrit-gwtexpui/src/main/java/com/google/gwtexpui/linker/server/UserAgentRule.java b/gerrit-gwtexpui/src/main/java/com/google/gwtexpui/linker/server/UserAgentRule.java
index 366b6c57a3..758578c643 100644
--- a/gerrit-gwtexpui/src/main/java/com/google/gwtexpui/linker/server/UserAgentRule.java
+++ b/gerrit-gwtexpui/src/main/java/com/google/gwtexpui/linker/server/UserAgentRule.java
@@ -45,13 +45,13 @@ public class UserAgentRule implements Rule {
 
     ua = ua.toLowerCase();
 
-    if (ua.indexOf("opera") != -1) {
+    if (ua.contains("opera")) {
       return "opera";
 
-    } else if (ua.indexOf("webkit") != -1) {
+    } else if (ua.contains("webkit")) {
       return "safari";
 
-    } else if (ua.indexOf("msie") != -1) {
+    } else if (ua.contains("msie")) {
       // GWT 2.0 uses document.documentMode here, which we can't do
       // on the server side.
 
@@ -73,7 +73,7 @@ public class UserAgentRule implements Rule {
       }
       return null;
 
-    } else if (ua.indexOf("gecko") != -1) {
+    } else if (ua.contains("gecko")) {
       Matcher m = gecko.matcher(ua);
       if (m.matches() && m.groupCount() == 2) {
         if (makeVersion(m) >= 1008) {
diff --git a/gerrit-httpd/src/main/java/com/google/gerrit/httpd/gitweb/GitWebServlet.java b/gerrit-httpd/src/main/java/com/google/gerrit/httpd/gitweb/GitWebServlet.java
index 0769865cf2..6aa3895613 100644
--- a/gerrit-httpd/src/main/java/com/google/gerrit/httpd/gitweb/GitWebServlet.java
+++ b/gerrit-httpd/src/main/java/com/google/gerrit/httpd/gitweb/GitWebServlet.java
@@ -123,7 +123,7 @@ class GitWebServlet extends HttpServlet {
 
     if (!_env.envMap.containsKey("SystemRoot")) {
       String os = System.getProperty("os.name");
-      if (os != null && os.toLowerCase().indexOf("windows") != -1) {
+      if (os != null && os.toLowerCase().contains("windows")) {
         String sysroot = System.getenv("SystemRoot");
         if (sysroot == null || sysroot.isEmpty()) {
           sysroot = "C:\\WINDOWS";
diff --git a/gerrit-httpd/src/main/java/com/google/gerrit/httpd/restapi/RestApiServlet.java b/gerrit-httpd/src/main/java/com/google/gerrit/httpd/restapi/RestApiServlet.java
index 636ccaf48c..983d5dae60 100644
--- a/gerrit-httpd/src/main/java/com/google/gerrit/httpd/restapi/RestApiServlet.java
+++ b/gerrit-httpd/src/main/java/com/google/gerrit/httpd/restapi/RestApiServlet.java
@@ -931,7 +931,7 @@ public class RestApiServlet extends HttpServlet {
   private static boolean acceptsGzip(HttpServletRequest req) {
     if (req != null) {
       String accepts = req.getHeader(HttpHeaders.ACCEPT_ENCODING);
-      return accepts != null && accepts.indexOf("gzip") != -1;
+      return accepts != null && accepts.contains("gzip");
     }
     return false;
   }
diff --git a/gerrit-pgm/src/main/java/com/google/gerrit/pgm/util/ProxyUtil.java b/gerrit-pgm/src/main/java/com/google/gerrit/pgm/util/ProxyUtil.java
index bc55b3c960..c2a52ece3e 100644
--- a/gerrit-pgm/src/main/java/com/google/gerrit/pgm/util/ProxyUtil.java
+++ b/gerrit-pgm/src/main/java/com/google/gerrit/pgm/util/ProxyUtil.java
@@ -61,7 +61,7 @@ final class ProxyUtil {
       return;
     }
 
-    final URL u = new URL((s.indexOf("://") == -1) ? "http://" + s : s);
+    final URL u = new URL((!s.contains("://")) ? "http://" + s : s);
     if (!"http".equals(u.getProtocol())) {
       throw new MalformedURLException("Invalid http_proxy: " + s
           + ": Only http supported.");
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/schema/Schema_81.java b/gerrit-server/src/main/java/com/google/gerrit/server/schema/Schema_81.java
index bc3b3907c6..1e3b2b7be5 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/schema/Schema_81.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/schema/Schema_81.java
@@ -80,7 +80,7 @@ public class Schema_81 extends SchemaVersion {
         public boolean accept(File pathname) {
           String n = pathname.getName();
           return (n.endsWith(".jar") || n.endsWith(".jar.disabled"))
-              && pathname.isFile() && n.indexOf("replication") >= 0;
+              && pathname.isFile() && n.contains("replication");
         }
       });
     }
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/util/HostPlatform.java b/gerrit-server/src/main/java/com/google/gerrit/server/util/HostPlatform.java
index 09594e2d6d..ea4b7f9842 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/util/HostPlatform.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/util/HostPlatform.java
@@ -33,7 +33,7 @@ public final class HostPlatform {
           }
         });
     return osDotName != null
-        && osDotName.toLowerCase().indexOf("windows") != -1;
+        && osDotName.toLowerCase().contains("windows");
   }
 
   private HostPlatform() {