diff --git a/java/rocksjni/comparator.cc b/java/rocksjni/comparator.cc
index 8dcda6aa6f..420897939d 100644
--- a/java/rocksjni/comparator.cc
+++ b/java/rocksjni/comparator.cc
@@ -18,7 +18,7 @@
 #include "rocksjni/comparatorjnicallback.h"
 #include "rocksjni/portal.h"
 
-//<editor-fold desc="org.rocksdb.ComparatorOptions">
+// <editor-fold desc="org.rocksdb.ComparatorOptions">
 
 void Java_org_rocksdb_ComparatorOptions_newComparatorOptions(
     JNIEnv* env, jobject jobj, jstring jpath, jboolean jshare_table_files,
@@ -37,10 +37,9 @@ void Java_org_rocksdb_ComparatorOptions_newComparatorOptions(
 
   rocksdb::BackupableDBOptionsJni::setHandle(env, jobj, bopt);
 }
+// </editor-fold>
 
-//</editor-fold>
-
-//<editor-fold desc="org.rocksdb.AbstractComparator>
+// <editor-fold desc="org.rocksdb.AbstractComparator>
 
 /*
  * Class:     org_rocksdb_AbstractComparator
@@ -51,10 +50,9 @@ void Java_org_rocksdb_AbstractComparator_disposeInternal(
     JNIEnv* env, jobject jobj, jlong handle) {
   delete reinterpret_cast<rocksdb::BaseComparatorJniCallback*>(handle);
 }
+// </editor-fold>
 
-//</editor-fold>
-
-//<editor-fold desc="org.rocksdb.Comparator>
+// <editor-fold desc="org.rocksdb.Comparator>
 
 /*
  * Class:     org_rocksdb_Comparator
@@ -63,14 +61,15 @@ void Java_org_rocksdb_AbstractComparator_disposeInternal(
  */
 void Java_org_rocksdb_Comparator_createNewComparator0(
     JNIEnv* env, jobject jobj, jlong copt_handle) {
-  const rocksdb::ComparatorJniCallbackOptions* copt = reinterpret_cast<rocksdb::ComparatorJniCallbackOptions*>(copt_handle);
-  const rocksdb::ComparatorJniCallback* c = new rocksdb::ComparatorJniCallback(env, jobj, copt);
+  const rocksdb::ComparatorJniCallbackOptions* copt =
+    reinterpret_cast<rocksdb::ComparatorJniCallbackOptions*>(copt_handle);
+  const rocksdb::ComparatorJniCallback* c =
+    new rocksdb::ComparatorJniCallback(env, jobj, copt);
   rocksdb::AbstractComparatorJni::setHandle(env, jobj, c);
 }
+// </editor-fold>
 
-//</editor-fold>
-
-//<editor-fold desc="org.rocksdb.DirectComparator>
+// <editor-fold desc="org.rocksdb.DirectComparator>
 
 /*
  * Class:     org_rocksdb_DirectComparator
@@ -79,10 +78,10 @@ void Java_org_rocksdb_Comparator_createNewComparator0(
  */
 void Java_org_rocksdb_DirectComparator_createNewDirectComparator0(
     JNIEnv* env, jobject jobj, jlong copt_handle) {
-  const rocksdb::ComparatorJniCallbackOptions* copt = reinterpret_cast<rocksdb::ComparatorJniCallbackOptions*>(copt_handle);
-  const rocksdb::DirectComparatorJniCallback* c = new rocksdb::DirectComparatorJniCallback(env, jobj, copt);
+  const rocksdb::ComparatorJniCallbackOptions* copt =
+    reinterpret_cast<rocksdb::ComparatorJniCallbackOptions*>(copt_handle);
+  const rocksdb::DirectComparatorJniCallback* c =
+    new rocksdb::DirectComparatorJniCallback(env, jobj, copt);
   rocksdb::AbstractComparatorJni::setHandle(env, jobj, c);
 }
-
-//</editor-fold>
-
+// </editor-fold>
diff --git a/java/rocksjni/comparatorjnicallback.cc b/java/rocksjni/comparatorjnicallback.cc
index 22bba334c7..1f271fe42c 100644
--- a/java/rocksjni/comparatorjnicallback.cc
+++ b/java/rocksjni/comparatorjnicallback.cc
@@ -7,14 +7,15 @@
 // rocksdb::Comparator.
 
 #include "rocksjni/comparatorjnicallback.h"
-#include "portal.h"
+#include "rocksjni/portal.h"
 
 namespace rocksdb {
 BaseComparatorJniCallback::BaseComparatorJniCallback(
-    JNIEnv* env, jobject jComparator, const ComparatorJniCallbackOptions* copt) {
+    JNIEnv* env, jobject jComparator,
+    const ComparatorJniCallbackOptions* copt) {
 
-  //mutex is used for synchronisation when we are re-using
-  //the global java slice objects
+  // mutex is used for synchronisation when we are re-using
+  // the global java slice objects
   mutex_ = new port::Mutex(copt->use_adaptive_mutex);
 
   // Note: Comparator methods may be accessed by multiple threads,
@@ -30,11 +31,13 @@ BaseComparatorJniCallback::BaseComparatorJniCallback(
   // so we cache it in a global var
   jmethodID jNameMethodId = AbstractComparatorJni::getNameMethodId(env);
   jstring jsName = (jstring)env->CallObjectMethod(m_jComparator, jNameMethodId);
-  m_name = JniUtil::copyString(env, jsName); //also releases jsName
+  m_name = JniUtil::copyString(env, jsName);  // also releases jsName
 
   m_jCompareMethodId = AbstractComparatorJni::getCompareMethodId(env);
-  m_jFindShortestSeparatorMethodId = AbstractComparatorJni::getFindShortestSeparatorMethodId(env);
-  m_jFindShortSuccessorMethodId = AbstractComparatorJni::getFindShortSuccessorMethodId(env);
+  m_jFindShortestSeparatorMethodId =
+    AbstractComparatorJni::getFindShortestSeparatorMethodId(env);
+  m_jFindShortSuccessorMethodId =
+    AbstractComparatorJni::getFindShortSuccessorMethodId(env);
 }
 
 /**
@@ -42,24 +45,25 @@ BaseComparatorJniCallback::BaseComparatorJniCallback(
  */
 JNIEnv* BaseComparatorJniCallback::getJniEnv() const {
   JNIEnv *env;
-  jint rs = m_jvm->AttachCurrentThread((void **)&env, NULL);
+  jint rs = m_jvm->AttachCurrentThread(reinterpret_cast<void **>(&env), NULL);
   assert(rs == JNI_OK);
   return env;
-};
+}
 
 const char* BaseComparatorJniCallback::Name() const {
   return m_name.c_str();
 }
 
 int BaseComparatorJniCallback::Compare(const Slice& a, const Slice& b) const {
-
   JNIEnv* m_env = getJniEnv();
 
   mutex_->Lock();
 
   AbstractSliceJni::setHandle(m_env, m_jSliceA, &a);
   AbstractSliceJni::setHandle(m_env, m_jSliceB, &b);
-  jint result = m_env->CallIntMethod(m_jComparator, m_jCompareMethodId, m_jSliceA, m_jSliceB);
+  jint result =
+    m_env->CallIntMethod(m_jComparator, m_jCompareMethodId, m_jSliceA,
+      m_jSliceB);
 
   mutex_->Unlock();
 
@@ -68,8 +72,8 @@ int BaseComparatorJniCallback::Compare(const Slice& a, const Slice& b) const {
   return result;
 }
 
-void BaseComparatorJniCallback::FindShortestSeparator(std::string* start, const Slice& limit) const {
-
+void BaseComparatorJniCallback::FindShortestSeparator(
+  std::string* start, const Slice& limit) const {
   if (start == nullptr) {
     return;
   }
@@ -82,22 +86,24 @@ void BaseComparatorJniCallback::FindShortestSeparator(std::string* start, const
   mutex_->Lock();
 
   AbstractSliceJni::setHandle(m_env, m_jSliceLimit, &limit);
-  jstring jsResultStart = (jstring)m_env->CallObjectMethod(m_jComparator, m_jFindShortestSeparatorMethodId, jsStart, m_jSliceLimit);
+  jstring jsResultStart =
+    (jstring)m_env->CallObjectMethod(m_jComparator,
+      m_jFindShortestSeparatorMethodId, jsStart, m_jSliceLimit);
 
   mutex_->Unlock();
 
   m_env->DeleteLocalRef(jsStart);
 
-  if(jsResultStart != nullptr) {
-    //update start with result
-    *start = JniUtil::copyString(m_env, jsResultStart); //also releases jsResultStart
+  if (jsResultStart != nullptr) {
+    // update start with result
+    *start =
+      JniUtil::copyString(m_env, jsResultStart);  // also releases jsResultStart
   }
 
   m_jvm->DetachCurrentThread();
 }
 
 void BaseComparatorJniCallback::FindShortSuccessor(std::string* key) const {
-
   if (key == nullptr) {
     return;
   }
@@ -107,13 +113,16 @@ void BaseComparatorJniCallback::FindShortSuccessor(std::string* key) const {
   const char* keyUtf = key->c_str();
   jstring jsKey = m_env->NewStringUTF(keyUtf);
 
-  jstring jsResultKey = (jstring)m_env->CallObjectMethod(m_jComparator, m_jFindShortSuccessorMethodId, jsKey);
+  jstring jsResultKey =
+    (jstring)m_env->CallObjectMethod(m_jComparator,
+      m_jFindShortSuccessorMethodId, jsKey);
 
   m_env->DeleteLocalRef(jsKey);
 
-  if(jsResultKey != nullptr) {
-    //update key with result
-    *key = JniUtil::copyString(m_env, jsResultKey); //also releases jsResultKey
+  if (jsResultKey != nullptr) {
+    // update key with result
+    *key =
+      JniUtil::copyString(m_env, jsResultKey);  // also releases jsResultKey
   }
 
   m_jvm->DetachCurrentThread();
@@ -121,7 +130,7 @@ void BaseComparatorJniCallback::FindShortSuccessor(std::string* key) const {
 
 BaseComparatorJniCallback::~BaseComparatorJniCallback() {
   JNIEnv* m_env = getJniEnv();
-  
+
   m_env->DeleteGlobalRef(m_jComparator);
   m_env->DeleteGlobalRef(m_jSliceA);
   m_env->DeleteGlobalRef(m_jSliceB);
@@ -129,21 +138,23 @@ BaseComparatorJniCallback::~BaseComparatorJniCallback() {
 
   // Note: do not need to explicitly detach, as this function is effectively
   // called from the Java class's disposeInternal method, and so already
-  // has an attached thread, getJniEnv above is just a no-op Attach to get the env
-  //jvm->DetachCurrentThread();
+  // has an attached thread, getJniEnv above is just a no-op Attach to get
+  // the env jvm->DetachCurrentThread();
 }
 
 ComparatorJniCallback::ComparatorJniCallback(
-    JNIEnv* env, jobject jComparator, const ComparatorJniCallbackOptions* copt) : BaseComparatorJniCallback(env, jComparator, copt) {
-
+    JNIEnv* env, jobject jComparator,
+    const ComparatorJniCallbackOptions* copt) :
+    BaseComparatorJniCallback(env, jComparator, copt) {
   m_jSliceA = env->NewGlobalRef(SliceJni::construct0(env));
   m_jSliceB = env->NewGlobalRef(SliceJni::construct0(env));
   m_jSliceLimit = env->NewGlobalRef(SliceJni::construct0(env));
 }
 
 DirectComparatorJniCallback::DirectComparatorJniCallback(
-    JNIEnv* env, jobject jComparator, const ComparatorJniCallbackOptions* copt) : BaseComparatorJniCallback(env, jComparator, copt) {
-
+    JNIEnv* env, jobject jComparator,
+    const ComparatorJniCallbackOptions* copt) :
+    BaseComparatorJniCallback(env, jComparator, copt) {
   m_jSliceA = env->NewGlobalRef(DirectSliceJni::construct0(env));
   m_jSliceB = env->NewGlobalRef(DirectSliceJni::construct0(env));
   m_jSliceLimit = env->NewGlobalRef(DirectSliceJni::construct0(env));
diff --git a/java/rocksjni/comparatorjnicallback.h b/java/rocksjni/comparatorjnicallback.h
index 8ca0ac64f2..cda32fce10 100644
--- a/java/rocksjni/comparatorjnicallback.h
+++ b/java/rocksjni/comparatorjnicallback.h
@@ -10,6 +10,7 @@
 #define JAVA_ROCKSJNI_COMPARATORJNICALLBACK_H_
 
 #include <jni.h>
+#include <string>
 #include "rocksdb/comparator.h"
 #include "rocksdb/slice.h"
 #include "port/port.h"
@@ -43,15 +44,18 @@ struct ComparatorJniCallbackOptions {
  * introduce locking in regions of those methods via mutex_.
  */
 class BaseComparatorJniCallback : public Comparator {
-  public:
-    BaseComparatorJniCallback(JNIEnv* env, jobject jComparator, const ComparatorJniCallbackOptions* copt);
+ public:
+    BaseComparatorJniCallback(
+      JNIEnv* env, jobject jComparator,
+      const ComparatorJniCallbackOptions* copt);
     virtual ~BaseComparatorJniCallback();
     virtual const char* Name() const;
     virtual int Compare(const Slice& a, const Slice& b) const;
-    virtual void FindShortestSeparator(std::string* start, const Slice& limit) const;
+    virtual void FindShortestSeparator(
+      std::string* start, const Slice& limit) const;
     virtual void FindShortSuccessor(std::string* key) const;
 
-  private:
+ private:
     port::Mutex* mutex_;
     JavaVM* m_jvm;
     jobject m_jComparator;
@@ -61,20 +65,24 @@ class BaseComparatorJniCallback : public Comparator {
     jmethodID m_jFindShortSuccessorMethodId;
     JNIEnv* getJniEnv() const;
 
-  protected:
+ protected:
     jobject m_jSliceA;
     jobject m_jSliceB;
     jobject m_jSliceLimit;
 };
 
 class ComparatorJniCallback : public BaseComparatorJniCallback {
-    public:
-      ComparatorJniCallback(JNIEnv* env, jobject jComparator, const ComparatorJniCallbackOptions* copt);
+ public:
+      ComparatorJniCallback(
+        JNIEnv* env, jobject jComparator,
+        const ComparatorJniCallbackOptions* copt);
 };
 
 class DirectComparatorJniCallback : public BaseComparatorJniCallback {
-    public:
-      DirectComparatorJniCallback(JNIEnv* env, jobject jComparator, const ComparatorJniCallbackOptions* copt);
+ public:
+      DirectComparatorJniCallback(
+        JNIEnv* env, jobject jComparator,
+        const ComparatorJniCallbackOptions* copt);
 };
 }  // namespace rocksdb
 
diff --git a/java/rocksjni/options.cc b/java/rocksjni/options.cc
index 4367fc708d..ceb4ce0311 100644
--- a/java/rocksjni/options.cc
+++ b/java/rocksjni/options.cc
@@ -16,6 +16,7 @@
 #include "include/org_rocksdb_ReadOptions.h"
 #include "include/org_rocksdb_ComparatorOptions.h"
 
+#include "rocksjni/comparatorjnicallback.h"
 #include "rocksjni/portal.h"
 #include "rocksdb/db.h"
 #include "rocksdb/options.h"
@@ -25,7 +26,6 @@
 #include "rocksdb/slice_transform.h"
 #include "rocksdb/rate_limiter.h"
 #include "rocksdb/comparator.h"
-#include "comparatorjnicallback.h"
 
 /*
  * Class:     org_rocksdb_Options
@@ -1794,7 +1794,8 @@ void Java_org_rocksdb_ComparatorOptions_newComparatorOptions(
  */
 jboolean Java_org_rocksdb_ComparatorOptions_useAdaptiveMutex(
     JNIEnv * env, jobject jobj, jlong jhandle) {
-  return reinterpret_cast<rocksdb::ComparatorJniCallbackOptions*>(jhandle)->use_adaptive_mutex;
+  return reinterpret_cast<rocksdb::ComparatorJniCallbackOptions*>(jhandle)
+    ->use_adaptive_mutex;
 }
 
 /*
@@ -1804,8 +1805,8 @@ jboolean Java_org_rocksdb_ComparatorOptions_useAdaptiveMutex(
  */
 void Java_org_rocksdb_ComparatorOptions_setUseAdaptiveMutex(
     JNIEnv * env, jobject jobj, jlong jhandle, jboolean juse_adaptive_mutex) {
-  reinterpret_cast<rocksdb::ComparatorJniCallbackOptions*>(jhandle)->use_adaptive_mutex =
-      static_cast<bool>(juse_adaptive_mutex);
+  reinterpret_cast<rocksdb::ComparatorJniCallbackOptions*>(jhandle)
+    ->use_adaptive_mutex = static_cast<bool>(juse_adaptive_mutex);
 }
 
 /*
diff --git a/java/rocksjni/portal.h b/java/rocksjni/portal.h
index bd40d4290f..32452ae0b4 100644
--- a/java/rocksjni/portal.h
+++ b/java/rocksjni/portal.h
@@ -12,6 +12,8 @@
 
 #include <jni.h>
 #include <limits>
+#include <string>
+
 #include "rocksdb/db.h"
 #include "rocksdb/filter_policy.h"
 #include "rocksdb/status.h"
@@ -364,7 +366,7 @@ class ColumnFamilyHandleJni {
 };
 
 class ComparatorOptionsJni {
-  public:
+ public:
     // Get the java class id of org.rocksdb.ComparatorOptions.
     static jclass getJClass(JNIEnv* env) {
       jclass jclazz = env->FindClass("org/rocksdb/ComparatorOptions");
@@ -383,7 +385,8 @@ class ComparatorOptionsJni {
 
     // Pass the ComparatorJniCallbackOptions pointer to the java side.
     static void setHandle(
-        JNIEnv* env, jobject jobj, const rocksdb::ComparatorJniCallbackOptions* op) {
+      JNIEnv* env, jobject jobj,
+      const rocksdb::ComparatorJniCallbackOptions* op) {
       env->SetLongField(
           jobj, getHandleFieldID(env),
           reinterpret_cast<jlong>(op));
@@ -418,37 +421,41 @@ class AbstractComparatorJni {
 
   // Get the java method `compare` of org.rocksdb.Comparator.
   static jmethodID getCompareMethodId(JNIEnv* env) {
-    static jmethodID mid = env->GetMethodID(
-        getJClass(env), "compare", "(Lorg/rocksdb/AbstractSlice;Lorg/rocksdb/AbstractSlice;)I");
+    static jmethodID mid = env->GetMethodID(getJClass(env),
+      "compare",
+      "(Lorg/rocksdb/AbstractSlice;Lorg/rocksdb/AbstractSlice;)I");
     assert(mid != nullptr);
     return mid;
   }
 
   // Get the java method `findShortestSeparator` of org.rocksdb.Comparator.
   static jmethodID getFindShortestSeparatorMethodId(JNIEnv* env) {
-    static jmethodID mid = env->GetMethodID(
-        getJClass(env), "findShortestSeparator", "(Ljava/lang/String;Lorg/rocksdb/AbstractSlice;)Ljava/lang/String;");
+    static jmethodID mid = env->GetMethodID(getJClass(env),
+      "findShortestSeparator",
+      "(Ljava/lang/String;Lorg/rocksdb/AbstractSlice;)Ljava/lang/String;");
     assert(mid != nullptr);
     return mid;
   }
 
   // Get the java method `findShortSuccessor` of org.rocksdb.Comparator.
   static jmethodID getFindShortSuccessorMethodId(JNIEnv* env) {
-    static jmethodID mid = env->GetMethodID(
-        getJClass(env), "findShortSuccessor", "(Ljava/lang/String;)Ljava/lang/String;");
+    static jmethodID mid = env->GetMethodID(getJClass(env),
+      "findShortSuccessor",
+      "(Ljava/lang/String;)Ljava/lang/String;");
     assert(mid != nullptr);
     return mid;
   }
 
   // Get the pointer to ComparatorJniCallback.
-  static rocksdb::BaseComparatorJniCallback* getHandle(JNIEnv* env, jobject jobj) {
+  static rocksdb::BaseComparatorJniCallback* getHandle(
+    JNIEnv* env, jobject jobj) {
     return reinterpret_cast<rocksdb::BaseComparatorJniCallback*>(
         env->GetLongField(jobj, getHandleFieldID(env)));
   }
 
   // Pass the ComparatorJniCallback pointer to the java side.
   static void setHandle(
-      JNIEnv* env, jobject jobj, const rocksdb::BaseComparatorJniCallback* op) {
+    JNIEnv* env, jobject jobj, const rocksdb::BaseComparatorJniCallback* op) {
     env->SetLongField(
         jobj, getHandleFieldID(env),
         reinterpret_cast<jlong>(op));
@@ -585,8 +592,7 @@ class ListJni {
 };
 
 class JniUtil {
-  public:
-
+ public:
     /**
      * Copies a jstring to a std::string
      * and releases the original jstring
diff --git a/java/rocksjni/slice.cc b/java/rocksjni/slice.cc
index e54b9a745a..0d8b92c9cf 100644
--- a/java/rocksjni/slice.cc
+++ b/java/rocksjni/slice.cc
@@ -17,7 +17,7 @@
 #include "rocksdb/slice.h"
 #include "rocksjni/portal.h"
 
-//<editor-fold desc="org.rocksdb.AbstractSlice>
+// <editor-fold desc="org.rocksdb.AbstractSlice>
 
 /*
  * Class:     org_rocksdb_AbstractSlice
@@ -73,7 +73,8 @@ jstring Java_org_rocksdb_AbstractSlice_toString0(
 jint Java_org_rocksdb_AbstractSlice_compare0(
     JNIEnv* env, jobject jobj, jlong handle, jlong otherHandle) {
   const rocksdb::Slice* slice = reinterpret_cast<rocksdb::Slice*>(handle);
-  const rocksdb::Slice* otherSlice = reinterpret_cast<rocksdb::Slice*>(otherHandle);
+  const rocksdb::Slice* otherSlice =
+    reinterpret_cast<rocksdb::Slice*>(otherHandle);
   return slice->compare(*otherSlice);
 }
 
@@ -85,7 +86,8 @@ jint Java_org_rocksdb_AbstractSlice_compare0(
 jboolean Java_org_rocksdb_AbstractSlice_startsWith0(
     JNIEnv* env, jobject jobj, jlong handle, jlong otherHandle) {
   const rocksdb::Slice* slice = reinterpret_cast<rocksdb::Slice*>(handle);
-  const rocksdb::Slice* otherSlice = reinterpret_cast<rocksdb::Slice*>(otherHandle);
+  const rocksdb::Slice* otherSlice =
+    reinterpret_cast<rocksdb::Slice*>(otherHandle);
   return slice->starts_with(*otherSlice);
 }
 
@@ -99,9 +101,9 @@ void Java_org_rocksdb_AbstractSlice_disposeInternal(
   delete reinterpret_cast<rocksdb::Slice*>(handle);
 }
 
-//</editor-fold>
+// </editor-fold>
 
-//<editor-fold desc="org.rocksdb.Slice>
+// <editor-fold desc="org.rocksdb.Slice>
 
 /*
  * Class:     org_rocksdb_Slice
@@ -113,13 +115,11 @@ void Java_org_rocksdb_Slice_createNewSlice0(
 
   const jsize dataSize = env->GetArrayLength(data);
   const int len = dataSize - offset;
-  //jbyte ptrData[len];
   jbyte* ptrData = new jbyte[len];
   env->GetByteArrayRegion(data, offset, len, ptrData);
 
   const rocksdb::Slice* slice = new rocksdb::Slice((const char*)ptrData, len);
   rocksdb::AbstractSliceJni::setHandle(env, jobj, slice);
-
 }
 
 /*
@@ -135,14 +135,15 @@ void Java_org_rocksdb_Slice_createNewSlice1(
   jboolean isCopy;
   jbyte* ptrData = env->GetByteArrayElements(data, &isCopy);
   const char* buf = new char[len];
-  memcpy((void*)buf, ptrData, len);
+  memcpy(const_cast<char*>(buf), ptrData, len);
 
-  const rocksdb::Slice* slice = new rocksdb::Slice(buf, env->GetArrayLength(data));
+  const rocksdb::Slice* slice =
+    new rocksdb::Slice(buf, env->GetArrayLength(data));
   rocksdb::AbstractSliceJni::setHandle(env, jobj, slice);
 
   env->ReleaseByteArrayElements(data, ptrData, JNI_ABORT);
 
-  //NOTE: buf will be deleted in the org.rocksdb.Slice#dispose method
+  // NOTE: buf will be deleted in the org.rocksdb.Slice#dispose method
 }
 
 /*
@@ -155,7 +156,8 @@ jbyteArray Java_org_rocksdb_Slice_data0(
   const rocksdb::Slice* slice = reinterpret_cast<rocksdb::Slice*>(handle);
   const int len = slice->size();
   const jbyteArray data = env->NewByteArray(len);
-  env->SetByteArrayRegion(data, 0, len, (jbyte*)slice->data());
+  env->SetByteArrayRegion(data, 0, len,
+    reinterpret_cast<jbyte*>(const_cast<char*>(slice->data())));
   return data;
 }
 
@@ -170,9 +172,9 @@ void Java_org_rocksdb_Slice_disposeInternalBuf(
     delete [] slice->data_;
 }
 
-//</editor-fold>
+// </editor-fold>
 
-//<editor-fold desc="org.rocksdb.DirectSlice>
+// <editor-fold desc="org.rocksdb.DirectSlice>
 
 /*
  * Class:     org_rocksdb_DirectSlice
@@ -181,7 +183,8 @@ void Java_org_rocksdb_Slice_disposeInternalBuf(
  */
 void Java_org_rocksdb_DirectSlice_createNewDirectSlice0(
     JNIEnv* env, jobject jobj, jobject data, jint length) {
-  const char* ptrData = (char*)env->GetDirectBufferAddress(data);
+  const char* ptrData =
+    reinterpret_cast<char*>(env->GetDirectBufferAddress(data));
   const rocksdb::Slice* slice = new rocksdb::Slice(ptrData, length);
   rocksdb::AbstractSliceJni::setHandle(env, jobj, slice);
 }
@@ -193,7 +196,8 @@ void Java_org_rocksdb_DirectSlice_createNewDirectSlice0(
  */
 void Java_org_rocksdb_DirectSlice_createNewDirectSlice1(
     JNIEnv* env, jobject jobj, jobject data) {
-  const char* ptrData = (char*)env->GetDirectBufferAddress(data);
+  const char* ptrData =
+    reinterpret_cast<char*>(env->GetDirectBufferAddress(data));
   const rocksdb::Slice* slice = new rocksdb::Slice(ptrData);
   rocksdb::AbstractSliceJni::setHandle(env, jobj, slice);
 }
@@ -206,7 +210,8 @@ void Java_org_rocksdb_DirectSlice_createNewDirectSlice1(
 jobject Java_org_rocksdb_DirectSlice_data0(
     JNIEnv* env, jobject jobj, jlong handle) {
   const rocksdb::Slice* slice = reinterpret_cast<rocksdb::Slice*>(handle);
-  return env->NewDirectByteBuffer((void*)slice->data(), slice->size());
+  return env->NewDirectByteBuffer(const_cast<char*>(slice->data()),
+    slice->size());
 }
 
 /*
@@ -228,6 +233,7 @@ jbyte Java_org_rocksdb_DirectSlice_get0(
 void Java_org_rocksdb_DirectSlice_clear0(
     JNIEnv* env, jobject jobj, jlong handle) {
   rocksdb::Slice* slice = reinterpret_cast<rocksdb::Slice*>(handle);
+  delete [] slice->data_;
   slice->clear();
 }
 
@@ -242,4 +248,4 @@ void Java_org_rocksdb_DirectSlice_removePrefix0(
   slice->remove_prefix(length);
 }
 
-//</editor-fold>
+// </editor-fold>