diff --git a/boot/src/main/java/com/taobao/arthas/boot/ProcessUtils.java b/boot/src/main/java/com/taobao/arthas/boot/ProcessUtils.java
index 33a94e21b..d6ed32c5f 100644
--- a/boot/src/main/java/com/taobao/arthas/boot/ProcessUtils.java
+++ b/boot/src/main/java/com/taobao/arthas/boot/ProcessUtils.java
@@ -375,7 +375,7 @@ public class ProcessUtils {
 
         // find the shortest path, jre path longer than jdk path
         if (javaList.size() > 1) {
-            Collections.sort(javaList, new Comparator<File>() {
+            javaList.sort(new Comparator<File>() {
                 @Override
                 public int compare(File file1, File file2) {
                     try {
diff --git a/core/src/main/java/com/taobao/arthas/core/shell/cli/CompletionUtils.java b/core/src/main/java/com/taobao/arthas/core/shell/cli/CompletionUtils.java
index f2e51e267..61525852c 100644
--- a/core/src/main/java/com/taobao/arthas/core/shell/cli/CompletionUtils.java
+++ b/core/src/main/java/com/taobao/arthas/core/shell/cli/CompletionUtils.java
@@ -209,10 +209,8 @@ public class CompletionUtils {
         // retrieve the class name
         String className;
         if (StringUtils.isBlank(lastToken)) {
-            // tokens = { " ", "CLASS_NAME", " "}
             className = tokens.get(tokens.size() - 2).value();
         } else {
-            // tokens = { " ", "CLASS_NAME", " ", "PARTIAL_METHOD_NAME"}
             className = tokens.get(tokens.size() - 3).value();
         }
 
diff --git a/core/src/main/java/com/taobao/arthas/core/shell/cli/impl/CliTokenImpl.java b/core/src/main/java/com/taobao/arthas/core/shell/cli/impl/CliTokenImpl.java
index ca956e556..8d30f7525 100644
--- a/core/src/main/java/com/taobao/arthas/core/shell/cli/impl/CliTokenImpl.java
+++ b/core/src/main/java/com/taobao/arthas/core/shell/cli/impl/CliTokenImpl.java
@@ -36,10 +36,12 @@ public class CliTokenImpl implements CliToken {
         return !text;
     }
 
+    @Override
     public String raw() {
         return raw;
     }
 
+    @Override
     public String value() {
         return value;
     }
diff --git a/core/src/main/java/com/taobao/arthas/core/shell/session/impl/SessionManagerImpl.java b/core/src/main/java/com/taobao/arthas/core/shell/session/impl/SessionManagerImpl.java
index 3edf548be..899c84a61 100644
--- a/core/src/main/java/com/taobao/arthas/core/shell/session/impl/SessionManagerImpl.java
+++ b/core/src/main/java/com/taobao/arthas/core/shell/session/impl/SessionManagerImpl.java
@@ -55,8 +55,6 @@ public class SessionManagerImpl implements SessionManager {
         session.put(Session.COMMAND_MANAGER, commandManager);
         session.put(Session.INSTRUMENTATION, instrumentation);
         session.put(Session.PID, pid);
-        //session.put(Session.SERVER, server);
-        //session.put(Session.TTY, term);
         String sessionId = UUID.randomUUID().toString();
         session.put(Session.ID, sessionId);