diff --git a/java/src/main/java/org/rocksdb/AbstractComparator.java b/java/src/main/java/org/rocksdb/AbstractComparator.java
index 1abdb4774..c2412d7f2 100644
--- a/java/src/main/java/org/rocksdb/AbstractComparator.java
+++ b/java/src/main/java/org/rocksdb/AbstractComparator.java
@@ -14,7 +14,7 @@ package org.rocksdb;
  *   @see org.rocksdb.Comparator
  *   @see org.rocksdb.DirectComparator
  */
-public abstract class AbstractComparator<T extends AbstractSlice>
+public abstract class AbstractComparator<T extends AbstractSlice<?>>
     extends RocksObject {
 
   /**
diff --git a/java/src/main/java/org/rocksdb/AbstractSlice.java b/java/src/main/java/org/rocksdb/AbstractSlice.java
index 2b0d80c6f..20fba41ac 100644
--- a/java/src/main/java/org/rocksdb/AbstractSlice.java
+++ b/java/src/main/java/org/rocksdb/AbstractSlice.java
@@ -99,7 +99,7 @@ abstract class AbstractSlice<T> extends RocksObject {
    *    2) == 0 if this == other
    *    3) &gt; 0 if this &gt; other
    */
-  public int compare(final AbstractSlice other) {
+  public int compare(final AbstractSlice<?> other) {
     assert (other != null);
     assert (isInitialized());
     return compare0(nativeHandle_, other.nativeHandle_);
@@ -118,7 +118,7 @@ abstract class AbstractSlice<T> extends RocksObject {
   @Override
   public boolean equals(final Object other) {
     if (other != null && other instanceof AbstractSlice) {
-      return compare((AbstractSlice)other) == 0;
+      return compare((AbstractSlice<?>)other) == 0;
     } else {
       return false;
     }
@@ -134,7 +134,7 @@ abstract class AbstractSlice<T> extends RocksObject {
    * @return true when this slice starts with the
    *   {@code prefix} slice
    */
-  public boolean startsWith(final AbstractSlice prefix) {
+  public boolean startsWith(final AbstractSlice<?> prefix) {
     if (prefix != null) {
       assert (isInitialized());
       return startsWith0(nativeHandle_, prefix.nativeHandle_);
diff --git a/java/src/main/java/org/rocksdb/ColumnFamilyOptions.java b/java/src/main/java/org/rocksdb/ColumnFamilyOptions.java
index 898a6cb45..d7783c90c 100644
--- a/java/src/main/java/org/rocksdb/ColumnFamilyOptions.java
+++ b/java/src/main/java/org/rocksdb/ColumnFamilyOptions.java
@@ -118,7 +118,8 @@ public class ColumnFamilyOptions extends RocksObject
   }
 
   @Override
-  public ColumnFamilyOptions setComparator(AbstractComparator comparator) {
+  public ColumnFamilyOptions setComparator(
+      AbstractComparator<? extends AbstractSlice<?>> comparator) {
     assert (isInitialized());
     setComparatorHandle(nativeHandle_, comparator.nativeHandle_);
     comparator_ = comparator;
@@ -705,5 +706,5 @@ public class ColumnFamilyOptions extends RocksObject
 
   MemTableConfig memTableConfig_;
   TableFormatConfig tableFormatConfig_;
-  AbstractComparator comparator_;
+  AbstractComparator<? extends AbstractSlice<?>> comparator_;
 }
diff --git a/java/src/main/java/org/rocksdb/ColumnFamilyOptionsInterface.java b/java/src/main/java/org/rocksdb/ColumnFamilyOptionsInterface.java
index c1be7f294..e2e55ffb3 100644
--- a/java/src/main/java/org/rocksdb/ColumnFamilyOptionsInterface.java
+++ b/java/src/main/java/org/rocksdb/ColumnFamilyOptionsInterface.java
@@ -109,7 +109,7 @@ public interface ColumnFamilyOptionsInterface {
    * @param comparator java instance.
    * @return the instance of the current Object.
    */
-  Object setComparator(AbstractComparator comparator);
+  Object setComparator(AbstractComparator<? extends AbstractSlice<?>> comparator);
 
   /**
    * <p>Set the merge operator to be used for merging two merge operands
diff --git a/java/src/main/java/org/rocksdb/Options.java b/java/src/main/java/org/rocksdb/Options.java
index 56385154d..f99783209 100644
--- a/java/src/main/java/org/rocksdb/Options.java
+++ b/java/src/main/java/org/rocksdb/Options.java
@@ -163,7 +163,8 @@ public class Options extends RocksObject
   }
 
   @Override
-  public Options setComparator(AbstractComparator comparator) {
+  public Options setComparator(
+      AbstractComparator<? extends AbstractSlice<?>> comparator) {
     assert (isInitialized());
     setComparatorHandle(nativeHandle_, comparator.nativeHandle_);
     comparator_ = comparator;
@@ -1253,5 +1254,5 @@ public class Options extends RocksObject
   MemTableConfig memTableConfig_;
   TableFormatConfig tableFormatConfig_;
   RateLimiterConfig rateLimiterConfig_;
-  AbstractComparator comparator_;
+  AbstractComparator<? extends AbstractSlice<?>> comparator_;
 }
diff --git a/java/src/main/java/org/rocksdb/WriteBatchWithIndex.java b/java/src/main/java/org/rocksdb/WriteBatchWithIndex.java
index 5204146c4..bddf04d7a 100644
--- a/java/src/main/java/org/rocksdb/WriteBatchWithIndex.java
+++ b/java/src/main/java/org/rocksdb/WriteBatchWithIndex.java
@@ -58,8 +58,8 @@ public class WriteBatchWithIndex extends AbstractWriteBatch {
    *   inserting a duplicate key, in this way an iterator will never
    *   show two entries with the same key.
    */
-  public WriteBatchWithIndex(AbstractComparator fallbackIndexComparator, int reservedBytes,
-      boolean overwriteKey) {
+  public WriteBatchWithIndex(AbstractComparator<? extends AbstractSlice<?>>
+      fallbackIndexComparator, int reservedBytes, boolean overwriteKey) {
     super();
     newWriteBatchWithIndex(fallbackIndexComparator.nativeHandle_, reservedBytes, overwriteKey);
   }