diff --git a/teavm-classlib/src/main/java/org/teavm/classlib/java/util/TAbstractMap.java b/teavm-classlib/src/main/java/org/teavm/classlib/java/util/TAbstractMap.java
new file mode 100644
index 000000000..8e422840c
--- /dev/null
+++ b/teavm-classlib/src/main/java/org/teavm/classlib/java/util/TAbstractMap.java
@@ -0,0 +1,275 @@
+/*
+ *  Copyright 2014 Alexey Andreev.
+ *
+ *  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 org.teavm.classlib.java.util;
+
+import org.teavm.classlib.java.io.TSerializable;
+import org.teavm.classlib.java.lang.TObject;
+import org.teavm.classlib.java.lang.TUnsupportedOperationException;
+
+/**
+ *
+ * @author Alexey Andreev <konsoletyper@gmail.com>
+ */
+public abstract class TAbstractMap<K, V> extends TObject implements TMap<K, V> {
+    public static class SimpleEntry<K, V> implements TMap.Entry<K, V>, TSerializable {
+        private K key;
+        private V value;
+
+        public SimpleEntry(K key, V value) {
+            this.key = key;
+            this.value = value;
+        }
+
+        public SimpleEntry(TMap.Entry<? extends K,? extends V> entry) {
+            this(entry.getKey(), entry.getValue());
+        }
+
+        @Override
+        public V getValue() {
+            return value;
+        }
+
+        @Override
+        public V setValue(V value) {
+            V old = this.value;
+            this.value = value;
+            return old;
+        }
+
+        @Override
+        public K getKey() {
+            return key;
+        }
+
+        @Override
+        public boolean equals(Object obj) {
+            if (!(obj instanceof TMap.Entry)) {
+                return false;
+            }
+            TMap.Entry<?, ?> other = (TMap.Entry<?, ?>)obj;
+            if (getKey() == null ? other.getKey() != null : !getKey().equals(other.getKey())) {
+                return false;
+            }
+            return getValue() == null ? other.getValue() == null : getValue().equals(other.getValue());
+        }
+
+        @Override
+        public int hashCode() {
+            return (getKey() == null ? 0 : getKey().hashCode()) ^ (getValue() == null ? 0 : getValue().hashCode());
+        }
+
+        @Override
+        public String toString() {
+            return String.valueOf(getKey()) + "=" + String.valueOf(getValue());
+        }
+    }
+
+    public static class SimpleImmutableEntry<K, V> implements TMap.Entry<K, V>, TSerializable {
+        private K key;
+        private V value;
+
+        public SimpleImmutableEntry(K key, V value) {
+            this.key = key;
+            this.value = value;
+        }
+
+        public SimpleImmutableEntry(TMap.Entry<? extends K,? extends V> entry) {
+            this(entry.getKey(), entry.getValue());
+        }
+
+        @Override
+        public V getValue() {
+            return value;
+        }
+
+        @Override
+        public V setValue(V value) {
+            throw new TUnsupportedOperationException();
+        }
+
+        @Override
+        public K getKey() {
+            return key;
+        }
+
+        @Override
+        public boolean equals(Object obj) {
+            if (!(obj instanceof TMap.Entry)) {
+                return false;
+            }
+            TMap.Entry<?, ?> other = (TMap.Entry<?, ?>)obj;
+            if (getKey() == null ? other.getKey() != null : !getKey().equals(other.getKey())) {
+                return false;
+            }
+            return getValue() == null ? other.getValue() == null : getValue().equals(other.getValue());
+        }
+
+        @Override
+        public int hashCode() {
+            return (getKey() == null ? 0 : getKey().hashCode()) ^ (getValue() == null ? 0 : getValue().hashCode());
+        }
+
+        @Override
+        public String toString() {
+            return String.valueOf(getKey()) + "=" + String.valueOf(getValue());
+        }
+    }
+
+    private KeySet cachedKeySet;
+    private Values cachedValues;
+
+    protected TAbstractMap() {
+    }
+
+    @Override
+    public int size() {
+        return entrySet().size();
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return size() == 0;
+    }
+
+    @Override
+    public boolean containsValue(Object value) {
+        for (TIterator<TMap.Entry<K, V>> iter = entrySet().iterator(); iter.hasNext();) {
+            V knownValue = iter.next().getValue();
+            if (TObjects.equals(value, knownValue)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    @Override
+    public boolean containsKey(Object key) {
+        for (TIterator<TMap.Entry<K, V>> iter = entrySet().iterator(); iter.hasNext();) {
+            K knownKey = iter.next().getKey();
+            if (TObjects.equals(key, knownKey)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    @Override
+    public V get(Object key) {
+        for (TIterator<TMap.Entry<K, V>> iter = entrySet().iterator(); iter.hasNext();) {
+            TMap.Entry<K, V> entry = iter.next();
+            if (TObjects.equals(key, entry.getKey())) {
+                return entry.getValue();
+            }
+        }
+        return null;
+    }
+
+    @Override
+    public V put(K key, V value) {
+        throw new TUnsupportedOperationException();
+    }
+
+    @Override
+    public void putAll(TMap<? extends K,? extends V> m) {
+        for (TIterator<? extends TMap.Entry<? extends K, ? extends V>> iter = m.entrySet().iterator();
+                iter.hasNext();) {
+            TMap.Entry<? extends K, ? extends V> entry = iter.next();
+            put(entry.getKey(), entry.getValue());
+        }
+    }
+
+    @Override
+    public V remove(Object key) {
+        for (TIterator<TMap.Entry<K, V>> iter = entrySet().iterator(); iter.hasNext();) {
+            TMap.Entry<K, V> entry = iter.next();
+            if (TObjects.equals(key, entry.getKey())) {
+                iter.remove();
+                return entry.getValue();
+            }
+        }
+        return null;
+    }
+
+    @Override
+    public abstract TSet<TMap.Entry<K,V>> entrySet();
+
+    @Override
+    public void clear() {
+        entrySet().clear();
+    }
+
+    @Override
+    public TSet<K> keySet() {
+        if (cachedKeySet == null) {
+            cachedKeySet = new KeySet();
+        }
+        return cachedKeySet;
+    }
+
+    @Override
+    public TCollection<V> values() {
+        if (cachedValues == null) {
+            cachedValues = new Values();
+        }
+        return cachedValues;
+    }
+
+    private class KeySet extends TAbstractSet<K> {
+        @Override
+        public TIterator<K> iterator() {
+            final TIterator<TMap.Entry<K, V>> iter = TAbstractMap.this.entrySet().iterator();
+            return new TIterator<K>() {
+                @Override public boolean hasNext() {
+                    return iter.hasNext();
+                }
+                @Override public K next() {
+                    return iter.next().getKey();
+                }
+                @Override public void remove() {
+                    iter.remove();
+                }
+            };
+        }
+
+        @Override
+        public int size() {
+            return TAbstractMap.this.size();
+        }
+    }
+
+    private class Values extends TAbstractCollection<V> {
+        @Override
+        public int size() {
+            return TAbstractMap.this.size();
+        }
+
+        @Override
+        public TIterator<V> iterator() {
+            final TIterator<TMap.Entry<K, V>> iter = TAbstractMap.this.entrySet().iterator();
+            return new TIterator<V>() {
+                @Override public boolean hasNext() {
+                    return iter.hasNext();
+                }
+                @Override public V next() {
+                    return iter.next().getValue();
+                }
+                @Override public void remove() {
+                    iter.remove();
+                }
+            };
+        }
+    }
+}
diff --git a/teavm-classlib/src/main/java/org/teavm/classlib/java/util/TAbstractSet.java b/teavm-classlib/src/main/java/org/teavm/classlib/java/util/TAbstractSet.java
new file mode 100644
index 000000000..9cced5978
--- /dev/null
+++ b/teavm-classlib/src/main/java/org/teavm/classlib/java/util/TAbstractSet.java
@@ -0,0 +1,47 @@
+/*
+ *  Copyright 2014 Alexey Andreev.
+ *
+ *  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 org.teavm.classlib.java.util;
+
+/**
+ *
+ * @author Alexey Andreev <konsoletyper@gmail.com>
+ */
+public abstract class TAbstractSet<E> extends TAbstractCollection<E> implements TSet<E> {
+    public TAbstractSet() {
+        super();
+    }
+
+    @Override
+    public boolean removeAll(TCollection<?> c) {
+        boolean modified = false;
+        if (size() < c.size()) {
+            for (TIterator<E> iter = iterator(); iter.hasNext();) {
+                E elem = iter.next();
+                if (c.contains(elem)) {
+                    modified = true;
+                    iter.remove();
+                }
+            }
+        } else {
+            for (TIterator<?> iter = c.iterator(); iter.hasNext();) {
+                if (remove(iter.next())) {
+                    modified = true;
+                }
+            }
+        }
+        return modified;
+    }
+}
diff --git a/teavm-classlib/src/main/java/org/teavm/classlib/java/util/TMap.java b/teavm-classlib/src/main/java/org/teavm/classlib/java/util/TMap.java
index 61f095350..a49464bc9 100644
--- a/teavm-classlib/src/main/java/org/teavm/classlib/java/util/TMap.java
+++ b/teavm-classlib/src/main/java/org/teavm/classlib/java/util/TMap.java
@@ -15,8 +15,6 @@
  */
 package org.teavm.classlib.java.util;
 
-import org.teavm.classlib.java.lang.TObject;
-
 /**
  *
  * @author Alexey Andreev <konsoletyper@gmail.com>
@@ -34,15 +32,15 @@ public interface TMap<K, V> {
 
     boolean isEmpty();
 
-    boolean containsKey(TObject key);
+    boolean containsKey(Object key);
 
-    boolean containsValue(TObject value);
+    boolean containsValue(Object value);
 
-    V get(TObject key);
+    V get(Object key);
 
     V put(K key, V value);
 
-    V remove(TObject key);
+    V remove(Object key);
 
     void putAll(TMap<? extends K,? extends V> m);
 
diff --git a/teavm-classlib/src/main/java/org/teavm/classlib/java/util/TObjects.java b/teavm-classlib/src/main/java/org/teavm/classlib/java/util/TObjects.java
new file mode 100644
index 000000000..24ce4c006
--- /dev/null
+++ b/teavm-classlib/src/main/java/org/teavm/classlib/java/util/TObjects.java
@@ -0,0 +1,58 @@
+/*
+ *  Copyright 2014 Alexey Andreev.
+ *
+ *  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 org.teavm.classlib.java.util;
+
+import org.teavm.classlib.java.lang.TObject;
+
+/**
+ *
+ * @author Alexey Andreev <konsoletyper@gmail.com>
+ */
+public final class TObjects extends TObject {
+    public static boolean equals(Object a, Object b) {
+        if (a == b) {
+            return true;
+        }
+        return a == null ? b == null : a.equals(b);
+    }
+
+    public static int hashCode(Object o) {
+        return o == null ? 0 : o.hashCode();
+    }
+
+    public static String toString(Object o) {
+        return toString(o, "null");
+    }
+
+    public static String toString(Object o, String nullDefault) {
+        return o != null ? o.toString() : nullDefault;
+    }
+
+    public static <T> int compare(T a, T b, TComparator<? super T> c) {
+        return a == null && b == null ? 0 : c.compare(a, b);
+    }
+
+    public static <T> T requireNonNull(T obj) {
+        return requireNonNull(obj, "");
+    }
+
+    public static <T> T requireNonNull(T obj, String message) {
+        if (obj == null) {
+            throw new NullPointerException(message);
+        }
+        return obj;
+    }
+}