diff --git a/src/dorkbox/collections/LockFreeIntStringMap.java b/src/dorkbox/collections/LockFreeIntStringMap.java
deleted file mode 100644
index b226698..0000000
--- a/src/dorkbox/collections/LockFreeIntStringMap.java
+++ /dev/null
@@ -1,225 +0,0 @@
-package dorkbox.collections;
-
-import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
-/**
- * This class uses the "single-writer-principle" for lock-free publication.
- * <p>
- * Since there are only 2 methods to guarantee that modifications can only be called one-at-a-time (either it is only called by
- * one thread, or only one thread can access it at a time) -- we chose the 2nd option -- and use 'synchronized' to make sure that only
- * one thread can access this modification methods at a time. Getting or checking the presence of values can then happen in a lock-free
- * manner.
- * <p>
- * According to my benchmarks, this is approximately 25% faster than ConcurrentHashMap for (all types of) reads, and a lot slower for
- * contended writes.
- * <p>
- * This data structure is for many-read/few-write scenarios
- *
- * This is an unordered map that uses int keys. This implementation is a cuckoo hash map using 3 hashes, random walking, and a small stash
- * for problematic keys. Null values are allowed. No allocation is done except when growing the table size. <br>
- * <br>
- * This map performs very fast get, containsKey, and remove (typically O(1), worst case O(log(n))). Put may be a bit slower,
- * depending on hash collisions. Load factors greater than 0.91 greatly increase the chances the map will have to rehash to the
- * next higher POT size.
- */
-@SuppressWarnings("unchecked")
-public
-class LockFreeIntStringMap<V> {
-    public static final String version = Collections.version;
-
-    private static final AtomicReferenceFieldUpdater<LockFreeIntStringMap, IntMap> mapREF = AtomicReferenceFieldUpdater.newUpdater(
-            LockFreeIntStringMap.class,
-            IntMap.class,
-            "map");
-
-    private volatile IntMap<V> map;
-
-
-    public LockFreeIntStringMap() {
-        this.map = new IntMap<V>();
-    }
-
-    /**
-     * Constructs an empty <tt>IntMap</tt> with the specified initial
-     * capacity and the default load factor (0.75).
-     *
-     * @param initialCapacity the initial capacity.
-     *
-     * @throws IllegalArgumentException if the initial capacity is negative.
-     */
-    public
-    LockFreeIntStringMap(int initialCapacity) {
-        map = new IntMap<V>(initialCapacity);
-    }
-
-    /**
-     * Constructs an empty <tt>IntMap</tt> with the specified initial
-     * capacity and the default load factor (0.75).
-     *
-     * @throws IllegalArgumentException if the initial capacity is negative.
-     */
-    public
-    LockFreeIntStringMap(LockFreeIntStringMap map) {
-        this.map = new IntMap<V>(map.map);
-    }
-
-    /**
-     * Constructs an empty <tt>IntMap</tt> with the specified initial
-     * capacity and load factor.
-     *
-     * @param initialCapacity the initial capacity
-     * @param loadFactor the load factor
-     *
-     * @throws IllegalArgumentException if the initial capacity is negative
-     *         or the load factor is nonpositive
-     */
-    public
-    LockFreeIntStringMap(int initialCapacity, float loadFactor) {
-        this.map = new IntMap<V>(initialCapacity, loadFactor);
-    }
-
-
-    public
-    int size() {
-        // use the SWP to get a lock-free get of the value
-        return mapREF.get(this)
-                       .size;
-    }
-
-    public
-    boolean isEmpty() {
-        // use the SWP to get a lock-free get of the value
-        return mapREF.get(this)
-                       .size == 0;
-    }
-
-    public
-    boolean containsKey(final int key) {
-        // use the SWP to get a lock-free get of the value
-        return mapREF.get(this)
-                     .containsKey(key);
-    }
-
-    public
-    boolean containsKey(final String key) {
-        // use the SWP to get a lock-free get of the value
-        return mapREF.get(this)
-                     .containsKey(key.hashCode());
-    }
-
-    /**
-     * Returns true if the specified value is in the map. Note this traverses the entire map and compares every value, which may be
-     * an expensive operation.
-     *
-     * @param identity If true, uses == to compare the specified value with values in the map. If false, uses
-     *         {@link #equals(Object)}.
-     */
-    public
-    boolean containsValue(final Object value, boolean identity) {
-        // use the SWP to get a lock-free get of the value
-        return mapREF.get(this)
-                     .containsValue(value, identity);
-    }
-
-    public
-    V get(final int key) {
-        // use the SWP to get a lock-free get of the value
-        return (V) mapREF.get(this)
-                         .get(key);
-    }
-
-    public
-    V get(final String key) {
-        // use the SWP to get a lock-free get of the value
-        return (V) mapREF.get(this)
-                         .get(key.hashCode());
-    }
-
-    public synchronized
-    V put(final int key, final V value) {
-        return map.put(key, value);
-    }
-
-    public synchronized
-    V put(final String key, final V value) {
-        return map.put(key.hashCode(), value);
-    }
-
-    public synchronized
-    V remove(final int key) {
-        return map.remove(key);
-    }
-
-    public synchronized
-    V remove(final String key) {
-        return map.remove(key.hashCode());
-    }
-
-    public synchronized
-    void putAll(final IntMap<V> map) {
-        this.map.putAll(map);
-    }
-
-    /**
-     * DO NOT MODIFY THE MAP VIA THIS (unless you synchronize around it!) It will result in unknown object visibility!
-     *
-     * Returns an iterator for the keys in the map. Remove is supported. Note that the same iterator instance is returned each
-     * time this method is called. Use the {@link IntMap.Entries} constructor for nested or multi-threaded iteration.
-     */
-    public
-    IntMap.Keys keys() {
-        return mapREF.get(this)
-                     .keys();
-    }
-
-    /**
-     * DO NOT MODIFY THE MAP VIA THIS (unless you synchronize around it!) It will result in unknown object visibility!
-     *
-     * Returns an iterator for the values in the map. Remove is supported. Note that the same iterator instance is returned each
-     * time this method is called. Use the {@link IntMap.Entries} constructor for nested or multi-threaded iteration.
-     */
-    public
-    IntMap.Values<V> values() {
-        return mapREF.get(this)
-                     .values();
-    }
-
-    /**
-     * DO NOT MODIFY THE MAP VIA THIS (unless you synchronize around it!) It will result in unknown object visibility!
-     *
-     * Returns an iterator for the entries in the map. Remove is supported. Note that the same iterator instance is returned each
-     * time this method is called. Use the {@link IntMap.Entries} constructor for nested or multi-threaded iteration.
-     */
-    public
-    IntMap.Entries<V> entries() {
-        return mapREF.get(this)
-                     .entries();
-    }
-
-    public synchronized
-    void clear() {
-        map.clear();
-    }
-
-    /**
-     * Identity equals only!
-     */
-    @Override
-    public
-    boolean equals(final Object o) {
-        return this == o;
-    }
-
-    @Override
-    public
-    int hashCode() {
-        return mapREF.get(this)
-                     .hashCode();
-    }
-
-    @Override
-    public
-    String toString() {
-        return mapREF.get(this)
-                     .toString();
-    }
-}
diff --git a/src/dorkbox/collections/LockFreeIntStringMap.kt b/src/dorkbox/collections/LockFreeIntStringMap.kt
new file mode 100644
index 0000000..d05b434
--- /dev/null
+++ b/src/dorkbox/collections/LockFreeIntStringMap.kt
@@ -0,0 +1,209 @@
+/*
+ * Copyright 2023 dorkbox, llc
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package dorkbox.collections
+
+import java.io.Serializable
+import java.util.concurrent.atomic.*
+
+/**
+ * This class uses the "single-writer-principle" for lock-free publication.
+ *
+ *
+ * Since there are only 2 methods to guarantee that modifications can only be called one-at-a-time (either it is only called by
+ * one thread, or only one thread can access it at a time) -- we chose the 2nd option -- and use 'synchronized' to make sure that only
+ * one thread can access this modification methods at a time. Getting or checking the presence of values can then happen in a lock-free
+ * manner.
+ *
+ *
+ * According to my benchmarks, this is approximately 25% faster than ConcurrentHashMap for (all types of) reads, and a lot slower for
+ * contended writes.
+ *
+ *
+ * This data structure is for many-read/few-write scenarios
+ */
+class LockFreeIntStringMap : MutableMap<Int, String?>, Cloneable, Serializable {
+
+    @Volatile
+    private var hashMap: IntMap<String?>
+
+
+    // synchronized is used here to ensure the "single writer principle", and make sure that ONLY one thread at a time can enter this
+    // section. Because of this, we can have unlimited reader threads all going at the same time, without contention (which is our
+    // use-case 99% of the time)
+
+    /**
+     * Constructs an empty <tt>HashMap</tt> with the default initial capacity
+     * (16) and the default load factor (0.75).
+     */
+    constructor() {
+        hashMap = IntMap()
+    }
+
+    /**
+     * Constructs an empty <tt>HashMap</tt> with the specified initial
+     * capacity and the default load factor (0.75).
+     *
+     * @param initialCapacity the initial capacity.
+     *
+     * @throws IllegalArgumentException if the initial capacity is negative.
+     */
+    constructor(initialCapacity: Int) {
+        hashMap = IntMap(initialCapacity)
+    }
+
+    /**
+     * Constructs a new <tt>HashMap</tt> with the same mappings as the
+     * specified <tt>Map</tt>.  The <tt>HashMap</tt> is created with
+     * default load factor (0.75) and an initial capacity sufficient to
+     * hold the mappings in the specified <tt>Map</tt>.
+     *
+     * @param map the map whose mappings are to be placed in this map
+     *
+     * @throws NullPointerException if the specified map is null
+     */
+    constructor(map: Map<Int, String?>) {
+        hashMap = IntMap(map.size)
+        map.forEach { (index, key) ->
+            hashMap.put(index, key)
+        }
+    }
+
+    constructor(map: LockFreeIntStringMap) {
+        hashMap = IntMap(map.hashMap)
+    }
+
+    /**
+     * Constructs an empty <tt>HashMap</tt> with the specified initial
+     * capacity and load factor.
+     *
+     * @param initialCapacity the initial capacity
+     * @param loadFactor the load factor
+     *
+     * @throws IllegalArgumentException if the initial capacity is negative
+     * or the load factor is nonpositive
+     */
+    constructor(initialCapacity: Int, loadFactor: Float) {
+        hashMap = IntMap(initialCapacity, loadFactor)
+    }
+
+    val map: IntMap<String>
+    get() {
+        @Suppress("UNCHECKED_CAST")
+        return mapREF[this] as IntMap<String>
+    }
+
+
+    override val size: Int
+        get() {
+            // use the SWP to get a lock-free get of the value
+            return mapREF[this].size
+        }
+
+    override val keys: MutableSet<Int>
+        get() {
+            return map.keys()
+        }
+
+    override val values: MutableCollection<String?>
+        get() {
+            @Suppress("UNCHECKED_CAST")
+            return map.values() as MutableCollection<String?>
+        }
+
+    override val entries: MutableSet<MutableMap.MutableEntry<Int, String?>>
+        get() {
+            @Suppress("UNCHECKED_CAST")
+            return map.entries() as MutableSet<MutableMap.MutableEntry<Int, String?>>
+        }
+
+    override fun isEmpty(): Boolean {
+        // use the SWP to get a lock-free get of the value
+        return mapREF[this].isEmpty()
+    }
+
+    override fun containsKey(key: Int): Boolean {
+        // use the SWP to get a lock-free get of the value
+        return mapREF[this].containsKey(key)
+    }
+
+    override fun containsValue(value: String?): Boolean {
+        // use the SWP to get a lock-free get of the value
+        return mapREF[this].containsValue(value)
+    }
+
+    override operator fun get(key: Int): String? {
+        return mapREF[this][key] as String?
+    }
+
+    @Synchronized
+    override fun put(key: Int, value: String?): String? {
+        return hashMap.put(key, value)
+    }
+
+    @Synchronized
+    override fun putAll(from: Map<out Int, String?>) {
+        hashMap.putAll(from)
+    }
+
+    @Synchronized
+    override fun remove(key: Int): String? {
+        return hashMap.remove(key)
+    }
+
+    @Synchronized
+    fun removeAllValues(value: String) {
+        val iterator = hashMap.entries().iterator()
+        while (iterator.hasNext()) {
+            val value1 = iterator.next()
+            if (value1.value == value) {
+                iterator.remove()
+            }
+        }
+    }
+
+    @Synchronized
+    fun replaceAll(hashMap: IntMap<String?>) {
+        this.hashMap.clear()
+        this.hashMap.putAll(hashMap)
+    }
+
+    @Synchronized
+    override fun clear() {
+        hashMap.clear()
+    }
+
+    override fun equals(other: Any?): Boolean {
+        return (mapREF[this] == other)
+    }
+
+    override fun hashCode(): Int {
+        return mapREF[this].hashCode()
+    }
+
+    override fun toString(): String {
+        return mapREF[this].toString()
+    }
+
+    // this must be at the end of the file!
+    companion object {
+        const val version = Collections.version
+
+        // Recommended for best performance while adhering to the "single writer principle". Must be static-final
+        private val mapREF = AtomicReferenceFieldUpdater.newUpdater(
+            LockFreeIntStringMap::class.java, IntMap::class.java, "hashMap"
+        )
+    }
+}