diff --git a/classlib/src/main/java/org/teavm/classlib/java/util/TAbstractMap.java b/classlib/src/main/java/org/teavm/classlib/java/util/TAbstractMap.java
index 550702dad..2246f76b8 100644
--- a/classlib/src/main/java/org/teavm/classlib/java/util/TAbstractMap.java
+++ b/classlib/src/main/java/org/teavm/classlib/java/util/TAbstractMap.java
@@ -292,7 +292,7 @@ public abstract class TAbstractMap<K, V> extends TObject implements TMap<K, V> {
     private class KeySet extends TAbstractSet<K> {
         @Override
         public TIterator<K> iterator() {
-            final TIterator<TMap.Entry<K, V>> it = TAbstractMap.this.entrySet().iterator();
+            final TIterator<TMap.Entry<K, V>> it = entrySet().iterator();
             return new TIterator<>() {
                 @Override public boolean hasNext() {
                     return it.hasNext();
@@ -320,16 +320,16 @@ public abstract class TAbstractMap<K, V> extends TObject implements TMap<K, V> {
 
         @Override
         public TIterator<V> iterator() {
-            final TIterator<TMap.Entry<K, V>> iter = TAbstractMap.this.entrySet().iterator();
-            return new TIterator<V>() {
+            final TIterator<TMap.Entry<K, V>> it = entrySet().iterator();
+            return new TIterator<>() {
                 @Override public boolean hasNext() {
-                    return iter.hasNext();
+                    return it.hasNext();
                 }
                 @Override public V next() {
-                    return iter.next().getValue();
+                    return it.next().getValue();
                 }
                 @Override public void remove() {
-                    iter.remove();
+                    it.remove();
                 }
             };
         }
diff --git a/classlib/src/main/java/org/teavm/classlib/java/util/TCollection.java b/classlib/src/main/java/org/teavm/classlib/java/util/TCollection.java
index 0b6979c88..3168da37a 100644
--- a/classlib/src/main/java/org/teavm/classlib/java/util/TCollection.java
+++ b/classlib/src/main/java/org/teavm/classlib/java/util/TCollection.java
@@ -15,7 +15,6 @@
  */
 package org.teavm.classlib.java.util;
 
-import java.util.Spliterator;
 import java.util.function.IntFunction;
 import java.util.function.Predicate;
 import org.teavm.classlib.java.lang.TIterable;
@@ -59,7 +58,7 @@ public interface TCollection<E> extends TIterable<E> {
 
     @SuppressWarnings("unchecked")
     default TStream<E> stream() {
-        return new TStreamOverSpliterator<>((Spliterator<E>) spliterator());
+        return new TStreamOverSpliterator<>(spliterator());
     }
 
     default boolean removeIf(Predicate<? super E> filter) {
diff --git a/classlib/src/main/java/org/teavm/classlib/java/util/TNavigableMap.java b/classlib/src/main/java/org/teavm/classlib/java/util/TNavigableMap.java
index 99fa032bc..ace028567 100644
--- a/classlib/src/main/java/org/teavm/classlib/java/util/TNavigableMap.java
+++ b/classlib/src/main/java/org/teavm/classlib/java/util/TNavigableMap.java
@@ -57,4 +57,14 @@ public interface TNavigableMap<K, V> extends TSortedMap<K, V> {
     TNavigableMap<K, V> headMap(K toKey, boolean inclusive);
 
     TNavigableMap<K, V> tailMap(K fromKey, boolean inclusive);
+
+    @Override
+    default TSequencedSet<K> sequencedKeySet() {
+        return navigableKeySet();
+    }
+
+    @Override
+    default TNavigableMap<K, V> reversed() {
+        return descendingMap();
+    }
 }
diff --git a/classlib/src/main/java/org/teavm/classlib/java/util/TNavigableSet.java b/classlib/src/main/java/org/teavm/classlib/java/util/TNavigableSet.java
index 0e2715d64..03073252f 100644
--- a/classlib/src/main/java/org/teavm/classlib/java/util/TNavigableSet.java
+++ b/classlib/src/main/java/org/teavm/classlib/java/util/TNavigableSet.java
@@ -42,4 +42,27 @@ public interface TNavigableSet<E> extends TSortedSet<E> {
     TNavigableSet<E> headSet(E toElement, boolean inclusive);
 
     TNavigableSet<E> tailSet(E fromElement, boolean inclusive);
+
+    @Override
+    default E removeFirst() {
+        if (isEmpty()) {
+            throw new TNoSuchElementException();
+        } else {
+            return pollFirst();
+        }
+    }
+
+    @Override
+    default E removeLast() {
+        if (isEmpty()) {
+            throw new TNoSuchElementException();
+        } else {
+            return pollLast();
+        }
+    }
+
+    @Override
+    default TNavigableSet<E> reversed() {
+        return descendingSet();
+    }
 }
diff --git a/classlib/src/main/java/org/teavm/classlib/java/util/TReversedSortedSet.java b/classlib/src/main/java/org/teavm/classlib/java/util/TReversedSortedSet.java
new file mode 100644
index 000000000..a24b2cab8
--- /dev/null
+++ b/classlib/src/main/java/org/teavm/classlib/java/util/TReversedSortedSet.java
@@ -0,0 +1,320 @@
+/*
+ *  Copyright 2023 ihromant.
+ *
+ *  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;
+
+class TReversedSortedSet<E> extends TAbstractSet<E> implements TSortedSet<E> {
+    private final TSortedSet<E> base;
+
+    TReversedSortedSet(TSortedSet<E> base) {
+        this.base = base;
+    }
+
+    @Override
+    public TIterator<E> iterator() {
+        return new DescendingSortedSetIterator<>(base);
+    }
+
+    @Override
+    public boolean add(E e) {
+        base.add(e);
+        return true;
+    }
+
+    @Override
+    public boolean addAll(TCollection<? extends E> c) {
+        return base.addAll(c);
+    }
+
+    @Override
+    public void clear() {
+        base.clear();
+    }
+
+    @Override
+    public boolean contains(Object o) {
+        return base.contains(o);
+    }
+
+    @Override
+    public boolean containsAll(TCollection<?> c) {
+        return base.containsAll(c);
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return base.isEmpty();
+    }
+
+    @Override
+    public boolean remove(Object o) {
+        return base.remove(o);
+    }
+
+    @Override
+    public E removeFirst() {
+        return base.removeLast();
+    }
+
+    @Override
+    public E removeLast() {
+        return base.removeFirst();
+    }
+
+    @Override
+    public boolean removeAll(TCollection<?> c) {
+        return base.removeAll(c);
+    }
+
+    @Override
+    public boolean retainAll(TCollection<?> c) {
+        return base.retainAll(c);
+    }
+
+    @Override
+    public int size() {
+        return base.size();
+    }
+
+    @Override
+    public TComparator<? super E> comparator() {
+        TComparator<? super E> comp = base.comparator();
+        return comp != null ? comp.reversed() : TCollections.reverseOrder();
+    }
+
+    @Override
+    public E first() {
+        return base.last();
+    }
+
+    @Override
+    public E last() {
+        return base.first();
+    }
+
+    @Override
+    public E getFirst() {
+        return base.last();
+    }
+
+    @Override
+    public E getLast() {
+        return base.first();
+    }
+
+    @Override
+    public TSortedSet<E> headSet(E to) {
+        return new DescSubset<>(base, null, to);
+    }
+
+    @Override
+    public TSortedSet<E> subSet(E from, E to) {
+        return new DescSubset<>(base, from, to);
+    }
+
+    @Override
+    public TSortedSet<E> tailSet(E from) {
+        return new DescSubset<>(base, from, null);
+    }
+
+    static class DescSubset<E> extends TAbstractSet<E> implements TSortedSet<E> {
+        final TSortedSet<E> base;
+        final E head;
+        final E tail;
+        private final TComparator<E> reversed;
+
+        @SuppressWarnings("unchecked")
+        DescSubset(TSortedSet<E> base, E head, E tail) {
+            this.base = base;
+            this.head = head;
+            this.tail = tail;
+            this.reversed = (TComparator<E>) TCollections.reverseOrder(base.comparator());
+        }
+
+        private boolean aboveHeadInc(E e) {
+            return head == null || reversed.compare(e, head) >= 0;
+        }
+
+        private boolean belowTailExc(E e) {
+            return tail == null || reversed.compare(e, tail) < 0;
+        }
+
+        @Override
+        public TIterator<E> iterator() {
+            return new TIterator<>() {
+                private final TIterator<E> it = new DescendingSortedSetIterator<>(base);
+                private E current;
+                private boolean finished;
+
+                @Override
+                public boolean hasNext() {
+                    if (finished) {
+                        return false;
+                    }
+                    if (current != null) {
+                        return true;
+                    }
+                    while (it.hasNext()) {
+                        E e = it.next();
+                        if (!aboveHeadInc(e)) {
+                            continue;
+                        }
+                        if (!belowTailExc(e)) {
+                            finished = true;
+                            return false;
+                        }
+                        current = e;
+                        return true;
+                    }
+                    return false;
+                }
+
+                @Override
+                public E next() {
+                    if (hasNext()) {
+                        E e = current;
+                        current = null;
+                        return e;
+                    } else {
+                        throw new TNoSuchElementException();
+                    }
+                }
+
+                @Override
+                public void remove() {
+                    throw new UnsupportedOperationException();
+                }
+            };
+        }
+
+        @Override
+        public boolean add(E e) {
+            if (aboveHeadInc(e) && belowTailExc(e)) {
+                return base.add(e);
+            } else {
+                throw new IllegalArgumentException();
+            }
+        }
+
+        @SuppressWarnings("unchecked")
+        @Override
+        public boolean remove(Object o) {
+            E e = (E) o;
+            if (aboveHeadInc(e) && belowTailExc(e)) {
+                return base.remove(o);
+            } else {
+                return false;
+            }
+        }
+
+        @Override
+        public int size() {
+            int size = 0;
+            for (var it = iterator(); it.hasNext(); it.next()) {
+                size++;
+            }
+            return size;
+        }
+
+        @Override
+        public TComparator<? super E> comparator() {
+            TComparator<? super E> comp = base.comparator();
+            return comp != null ? comp.reversed() : TCollections.reverseOrder();
+        }
+
+        @Override
+        public E first() {
+            return iterator().next();
+        }
+
+        @Override
+        public E last() {
+            TIterator<E> it = iterator();
+            if (!it.hasNext()) {
+                throw new TNoSuchElementException();
+            }
+            E last = it.next();
+            while (it.hasNext()) {
+                last = it.next();
+            }
+            return last;
+        }
+
+        @Override
+        public TSortedSet<E> subSet(E from, E to) {
+            if (aboveHeadInc(from) && belowTailExc(from)
+                    && aboveHeadInc(to) && belowTailExc(to)
+                    && reversed.compare(from, to) <= 0) {
+                return new DescSubset<>(base, from, to);
+            } else {
+                throw new IllegalArgumentException();
+            }
+        }
+
+        @Override
+        public TSortedSet<E> headSet(E to) {
+            if (aboveHeadInc(to) && belowTailExc(to)) {
+                return new DescSubset<>(base, head, to);
+            } else {
+                throw new IllegalArgumentException();
+            }
+        }
+
+        @Override
+        public TSortedSet<E> tailSet(E from) {
+            if (aboveHeadInc(from) && belowTailExc(from)) {
+                return new DescSubset<>(base, null, tail);
+            } else {
+                throw new IllegalArgumentException();
+            }
+        }
+    }
+
+    private static class DescendingSortedSetIterator<E> implements TIterator<E> {
+        private final TSortedSet<E> base;
+        private TSortedSet<E> remaining;
+        private E current;
+
+        private DescendingSortedSetIterator(TSortedSet<E> base) {
+            this.base = base;
+            this.remaining = base;
+        }
+
+        @Override
+        public boolean hasNext() {
+            return !remaining.isEmpty();
+        }
+
+        @Override
+        public E next() {
+            if (remaining.isEmpty()) {
+                throw new TNoSuchElementException();
+            }
+            current = remaining.last();
+            remaining = base.headSet(current);
+            return current;
+        }
+
+        @Override
+        public void remove() {
+            if (current == null) {
+                throw new IllegalStateException();
+            } else {
+                base.remove(current);
+                current = null;
+            }
+        }
+    }
+}
diff --git a/classlib/src/main/java/org/teavm/classlib/java/util/TSortedMap.java b/classlib/src/main/java/org/teavm/classlib/java/util/TSortedMap.java
index 4815accc3..0d5e715c6 100644
--- a/classlib/src/main/java/org/teavm/classlib/java/util/TSortedMap.java
+++ b/classlib/src/main/java/org/teavm/classlib/java/util/TSortedMap.java
@@ -21,7 +21,7 @@ package org.teavm.classlib.java.util;
  * @param <K>
  * @param <V>
  */
-public interface TSortedMap<K, V> extends TMap<K, V> {
+public interface TSortedMap<K, V> extends TSequencedMap<K, V> {
     TComparator<? super K> comparator();
 
     TSortedMap<K, V> subMap(K fromKey, K toKey);
diff --git a/classlib/src/main/java/org/teavm/classlib/java/util/TSortedSet.java b/classlib/src/main/java/org/teavm/classlib/java/util/TSortedSet.java
index d9d92be93..43368149c 100644
--- a/classlib/src/main/java/org/teavm/classlib/java/util/TSortedSet.java
+++ b/classlib/src/main/java/org/teavm/classlib/java/util/TSortedSet.java
@@ -20,7 +20,7 @@ package org.teavm.classlib.java.util;
  * @author Alexey Andreev
  * @param <E>
  */
-public interface TSortedSet<E> extends TSet<E> {
+public interface TSortedSet<E> extends TSet<E>, TSequencedSet<E> {
     TComparator<? super E> comparator();
 
     TSortedSet<E> subSet(E fromElement, E toElement);
@@ -32,4 +32,33 @@ public interface TSortedSet<E> extends TSet<E> {
     E first();
 
     E last();
+
+    @Override
+    default E getFirst() {
+        return first();
+    }
+
+    @Override
+    default E getLast() {
+        return last();
+    }
+
+    @Override
+    default E removeFirst() {
+        E e = this.first();
+        this.remove(e);
+        return e;
+    }
+
+    @Override
+    default E removeLast() {
+        E e = this.last();
+        this.remove(e);
+        return e;
+    }
+
+    @Override
+    default TSortedSet<E> reversed() {
+        return new TReversedSortedSet<>(this);
+    }
 }
diff --git a/classlib/src/main/java/org/teavm/classlib/java/util/TTreeMap.java b/classlib/src/main/java/org/teavm/classlib/java/util/TTreeMap.java
index 30775eff7..fad62b590 100644
--- a/classlib/src/main/java/org/teavm/classlib/java/util/TTreeMap.java
+++ b/classlib/src/main/java/org/teavm/classlib/java/util/TTreeMap.java
@@ -364,10 +364,7 @@ public class TTreeMap<K, V> extends TAbstractMap<K, V> implements TCloneable, TS
 
     @Override
     public TSet<Entry<K, V>> entrySet() {
-        if (cachedEntrySet == null) {
-            cachedEntrySet = new EntrySet<>(this, null, true, false, null, true, false, false);
-        }
-        return cachedEntrySet;
+        return sequencedEntrySet();
     }
 
     @Override
@@ -469,7 +466,7 @@ public class TTreeMap<K, V> extends TAbstractMap<K, V> implements TCloneable, TS
     public Entry<K, V> pollFirstEntry() {
         TreeNode<K, V> node = firstNode(false);
         if (node != null) {
-            root = deleteNode(root, node.getKey());
+            remove(node.getKey());
         }
         return node;
     }
@@ -478,11 +475,32 @@ public class TTreeMap<K, V> extends TAbstractMap<K, V> implements TCloneable, TS
     public Entry<K, V> pollLastEntry() {
         TreeNode<K, V> node = firstNode(true);
         if (node != null) {
-            root = deleteNode(root, node.getKey());
+            remove(node.getKey());
         }
         return node;
     }
 
+    @Override
+    public TCollection<V> values() {
+        return sequencedValues();
+    }
+
+    @Override
+    public TSequencedCollection<V> sequencedValues() {
+        if (cachedValues == null) {
+            cachedValues = new NavigableMapValues<>(this);
+        }
+        return (TSequencedCollection<V>) cachedValues;
+    }
+
+    @Override
+    public TSequencedSet<Entry<K, V>> sequencedEntrySet() {
+        if (cachedEntrySet == null) {
+            cachedEntrySet = new EntrySet<>(this, null, true, false, null, true, false, false);
+        }
+        return cachedEntrySet;
+    }
+
     @Override
     public TNavigableMap<K, V> descendingMap() {
         return new MapView<>(this, null, false, false, null, false, false, true);
@@ -542,7 +560,7 @@ public class TTreeMap<K, V> extends TAbstractMap<K, V> implements TCloneable, TS
         return copy;
     }
 
-    static class EntrySet<K, V> extends TAbstractSet<Entry<K, V>> {
+    static class EntrySet<K, V> extends TAbstractSet<Entry<K, V>> implements TSequencedSet<Entry<K, V>> {
         private int modCount = -1;
         private TTreeMap<K, V> owner;
         private K from;
@@ -619,7 +637,7 @@ public class TTreeMap<K, V> extends TAbstractMap<K, V> implements TCloneable, TS
             } else {
                 toPath = owner.pathToFirst(true);
             }
-            return new EntryIterator<>(owner, toPath, from, fromIncluded, fromChecked, true);
+            return new EntryIterator<>(owner, toPath, from, fromChecked, fromIncluded, true);
         }
 
         @Override
@@ -651,6 +669,11 @@ public class TTreeMap<K, V> extends TAbstractMap<K, V> implements TCloneable, TS
         public boolean isEmpty() {
             return size() == 0;
         }
+
+        @Override
+        public TSequencedSet<Entry<K, V>> reversed() {
+            return new EntrySet<>(owner, from, fromIncluded, fromChecked, to, toIncluded, toChecked, !reverse);
+        }
     }
 
     static class EntryIterator<K, V> implements TIterator<Entry<K, V>> {
@@ -772,11 +795,7 @@ public class TTreeMap<K, V> extends TAbstractMap<K, V> implements TCloneable, TS
 
         @Override
         public TSet<Entry<K, V>> entrySet() {
-            if (entrySetCache == null) {
-                entrySetCache = new EntrySet<>(owner, from, fromIncluded,
-                        fromChecked, to, toIncluded, toChecked, reverse);
-            }
-            return entrySetCache;
+            return sequencedEntrySet();
         }
 
         @Override
@@ -1021,7 +1040,7 @@ public class TTreeMap<K, V> extends TAbstractMap<K, V> implements TCloneable, TS
         public Entry<K, V> pollFirstEntry() {
             TreeNode<K, V> node = !reverse ? firstNode() : lastNode();
             if (node != null) {
-                owner.deleteNode(owner.root, node.getKey());
+                owner.remove(node.getKey());
             }
             return node;
         }
@@ -1030,11 +1049,33 @@ public class TTreeMap<K, V> extends TAbstractMap<K, V> implements TCloneable, TS
         public Entry<K, V> pollLastEntry() {
             TreeNode<K, V> node = !reverse ? lastNode() : firstNode();
             if (node != null) {
-                owner.deleteNode(owner.root, node.getKey());
+                owner.remove(node.getKey());
             }
             return node;
         }
 
+        @Override
+        public TCollection<V> values() {
+            return sequencedValues();
+        }
+
+        @Override
+        public TSequencedCollection<V> sequencedValues() {
+            if (cachedValues == null) {
+                cachedValues = new NavigableMapValues<>(this);
+            }
+            return (TSequencedCollection<V>) cachedValues;
+        }
+
+        @Override
+        public TSequencedSet<Entry<K, V>> sequencedEntrySet() {
+            if (entrySetCache == null) {
+                entrySetCache = new EntrySet<>(owner, from, fromIncluded,
+                        fromChecked, to, toIncluded, toChecked, reverse);
+            }
+            return entrySetCache;
+        }
+
         @Override
         public TNavigableMap<K, V> descendingMap() {
             return new MapView<>(owner, from, fromIncluded, fromChecked, to, toIncluded, toChecked, !reverse);
@@ -1086,13 +1127,13 @@ public class TTreeMap<K, V> extends TAbstractMap<K, V> implements TCloneable, TS
             if (!reverse) {
                 return new MapView<>(owner, fromKey, inclusive, true, to, toIncluded, toChecked, false);
             } else {
-                return new MapView<>(owner, from, fromIncluded, toChecked, fromKey, inclusive, true, true);
+                return new MapView<>(owner, from, fromIncluded, fromChecked, fromKey, inclusive, true, true);
             }
         }
     }
 
     static class NavigableKeySet<K, V> extends TAbstractSet<K> implements TNavigableSet<K> {
-        private TNavigableMap<K, V> map;
+        private final TNavigableMap<K, V> map;
 
         NavigableKeySet(TNavigableMap<K, V> map) {
             this.map = map;
@@ -1115,7 +1156,7 @@ public class TTreeMap<K, V> extends TAbstractMap<K, V> implements TCloneable, TS
 
         @Override
         public TSortedSet<K> tailSet(K fromElement) {
-            return map.headMap(fromElement, true).navigableKeySet();
+            return map.tailMap(fromElement, true).navigableKeySet();
         }
 
         @Override
@@ -1192,7 +1233,41 @@ public class TTreeMap<K, V> extends TAbstractMap<K, V> implements TCloneable, TS
 
         @Override
         public TNavigableSet<K> tailSet(K fromElement, boolean inclusive) {
-            return map.headMap(fromElement, inclusive).navigableKeySet();
+            return map.tailMap(fromElement, inclusive).navigableKeySet();
+        }
+    }
+
+    static class NavigableMapValues<K, V> extends TAbstractCollection<V> implements TSequencedCollection<V> {
+        private final TNavigableMap<K, V> map;
+
+        NavigableMapValues(TNavigableMap<K, V> map) {
+            this.map = map;
+        }
+
+        @Override
+        public int size() {
+            return map.size();
+        }
+
+        @Override
+        public TIterator<V> iterator() {
+            final TIterator<TMap.Entry<K, V>> it = map.entrySet().iterator();
+            return new TIterator<>() {
+                @Override public boolean hasNext() {
+                    return it.hasNext();
+                }
+                @Override public V next() {
+                    return it.next().getValue();
+                }
+                @Override public void remove() {
+                    it.remove();
+                }
+            };
+        }
+
+        @Override
+        public TSequencedCollection<V> reversed() {
+            return new NavigableMapValues<>(map.reversed());
         }
     }
 }
diff --git a/classlib/src/main/java/org/teavm/classlib/java/util/stream/TStreamSupport.java b/classlib/src/main/java/org/teavm/classlib/java/util/stream/TStreamSupport.java
index 66828478d..8a33baef3 100644
--- a/classlib/src/main/java/org/teavm/classlib/java/util/stream/TStreamSupport.java
+++ b/classlib/src/main/java/org/teavm/classlib/java/util/stream/TStreamSupport.java
@@ -17,6 +17,7 @@ package org.teavm.classlib.java.util.stream;
 
 import java.util.Spliterator;
 import java.util.function.Supplier;
+import org.teavm.classlib.java.util.TSpliterator;
 import org.teavm.classlib.java.util.stream.impl.TStreamOverSpliterator;
 import org.teavm.classlib.java.util.stream.impl.TStreamOverSpliteratorSupplier;
 
@@ -24,7 +25,7 @@ public final class TStreamSupport {
     private TStreamSupport() {
     }
 
-    public static <T> TStream<T> stream(Spliterator<T> spliterator, boolean parallel) {
+    public static <T> TStream<T> stream(TSpliterator<T> spliterator, boolean parallel) {
         return new TStreamOverSpliterator<>(spliterator);
     }
 
diff --git a/classlib/src/main/java/org/teavm/classlib/java/util/stream/impl/TStreamOverSpliterator.java b/classlib/src/main/java/org/teavm/classlib/java/util/stream/impl/TStreamOverSpliterator.java
index 92006c5fa..407a749de 100644
--- a/classlib/src/main/java/org/teavm/classlib/java/util/stream/impl/TStreamOverSpliterator.java
+++ b/classlib/src/main/java/org/teavm/classlib/java/util/stream/impl/TStreamOverSpliterator.java
@@ -18,11 +18,12 @@ package org.teavm.classlib.java.util.stream.impl;
 import java.util.Spliterator;
 import java.util.function.Consumer;
 import java.util.function.Predicate;
+import org.teavm.classlib.java.util.TSpliterator;
 
 public class TStreamOverSpliterator<T> extends TSimpleStreamImpl<T> {
-    private Spliterator<T> spliterator;
+    private TSpliterator<T> spliterator;
 
-    public TStreamOverSpliterator(Spliterator<T> spliterator) {
+    public TStreamOverSpliterator(TSpliterator<T> spliterator) {
         this.spliterator = spliterator;
     }
 
diff --git a/tests/src/test/java/org/teavm/classlib/java/util/TreeMapTest.java b/tests/src/test/java/org/teavm/classlib/java/util/TreeMapTest.java
index 6b13f2ae8..06e05e08a 100644
--- a/tests/src/test/java/org/teavm/classlib/java/util/TreeMapTest.java
+++ b/tests/src/test/java/org/teavm/classlib/java/util/TreeMapTest.java
@@ -47,6 +47,7 @@
  */
 package org.teavm.classlib.java.util;
 
+import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotSame;
@@ -55,15 +56,21 @@ import static org.junit.Assert.assertSame;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 import java.io.Serializable;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.Iterator;
+import java.util.List;
 import java.util.Map;
 import java.util.NavigableMap;
+import java.util.NoSuchElementException;
+import java.util.SequencedMap;
 import java.util.Set;
 import java.util.SortedMap;
 import java.util.TreeMap;
+import java.util.function.Function;
+import java.util.stream.Collectors;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.teavm.junit.TeaVMTestRunner;
@@ -728,4 +735,124 @@ public class TreeMapTest {
             }
         }
     }
+
+    private static final List<Integer> BASE_LIST = Arrays.asList(1, 6, 2, 5, 3, 4);
+
+    private SequencedMap<Integer, String> generateMap() {
+        return BASE_LIST.stream().collect(Collectors.toMap(Function.identity(), i -> Integer.toString(i),
+                (a, b) -> a, TreeMap::new));
+    }
+
+    @Test
+    public void testSequencedMap() {
+        SequencedMap<Integer, String> map = generateMap();
+        assertEquals(Map.entry(1, "1"), map.pollFirstEntry());
+        assertArrayEquals(new Integer[] { 2, 3, 4, 5, 6 }, map.keySet().toArray(new Integer[0]));
+        assertEquals(Map.entry(6, "6"), map.pollLastEntry());
+        assertArrayEquals(new Integer[] { 2, 3, 4, 5 }, map.keySet().toArray(new Integer[0]));
+        assertEquals(Map.entry(5, "5"), map.pollLastEntry());
+        assertArrayEquals(new Integer[] { 2, 3, 4 }, map.keySet().toArray(new Integer[0]));
+        assertEquals(Map.entry(2, "2"), map.firstEntry());
+        assertEquals(Map.entry(4, "4"), map.lastEntry());
+        try {
+            map.putFirst(1, "1");
+            fail();
+        } catch (UnsupportedOperationException e) {
+            // ok
+        }
+        map.put(7, "7");
+        try {
+            map.putLast(3, "3");
+            fail();
+        } catch (UnsupportedOperationException e) {
+            // ok
+        }
+        assertArrayEquals(new Integer[] { 2, 3, 4, 7 }, map.keySet().toArray(new Integer[0]));
+        map = generateMap().reversed();
+        assertEquals(Map.entry(6, "6"), map.pollFirstEntry());
+        assertArrayEquals(new Integer[] { 5, 4, 3, 2, 1 }, map.keySet().toArray(new Integer[0]));
+        assertEquals(Map.entry(1, "1"), map.pollLastEntry());
+        assertArrayEquals(new Integer[] { 5, 4, 3, 2 }, map.keySet().toArray(new Integer[0]));
+        assertEquals(Map.entry(2, "2"), map.pollLastEntry());
+        assertArrayEquals(new Integer[] { 5, 4, 3 }, map.keySet().toArray(new Integer[0]));
+        assertEquals(Map.entry(5, "5"), map.firstEntry());
+        assertEquals(Map.entry(3, "3"), map.lastEntry());
+        try {
+            map.putFirst(1, "1");
+            fail();
+        } catch (UnsupportedOperationException e) {
+            // ok
+        }
+        map.put(7, "7");
+        try {
+            map.putLast(6, "6");
+            fail();
+        } catch (UnsupportedOperationException e) {
+            // ok
+        }
+        assertArrayEquals(new Integer[] { 7, 5, 4, 3 }, map.keySet().toArray(new Integer[0]));
+    }
+
+    @Test
+    public void testSequencedIterators() {
+        SequencedMap<Integer, String> map = generateMap();
+        Iterator<Integer> it = map.keySet().iterator();
+        assertTrue(it.hasNext());
+        assertEquals(1, it.next().intValue());
+        assertTrue(it.hasNext());
+        assertEquals(2, it.next().intValue());
+        it.remove();
+        assertArrayEquals(new Integer[] { 1, 3, 4, 5, 6 }, map.keySet().toArray(new Integer[0]));
+        map = map.reversed();
+        it = map.keySet().iterator();
+        assertTrue(it.hasNext());
+        assertEquals(6, it.next().intValue());
+        assertTrue(it.hasNext());
+        assertEquals(5, it.next().intValue());
+        it.remove();
+        assertArrayEquals(new Integer[] { 6, 4, 3, 1 }, map.keySet().toArray(new Integer[0]));
+        map = generateMap();
+        Iterator<String> sit = map.sequencedValues().iterator();
+        assertTrue(sit.hasNext());
+        assertEquals("1", sit.next());
+        assertTrue(sit.hasNext());
+        assertEquals("2", sit.next());
+        sit.remove();
+        assertArrayEquals(new String[] { "1", "3", "4", "5", "6" }, map.values().toArray(new String[0]));
+        map = map.reversed();
+        sit = map.sequencedValues().iterator();
+        assertTrue(sit.hasNext());
+        assertEquals("6", sit.next());
+        assertTrue(sit.hasNext());
+        assertEquals("5", sit.next());
+        sit.remove();
+        assertArrayEquals(new String[] { "6", "4", "3", "1" }, map.values().toArray(new String[0]));
+    }
+
+    @Test
+    public void testEmpty() {
+        var empty = new TreeMap<>();
+        assertNull(empty.pollFirstEntry());
+        assertNull(empty.pollLastEntry());
+        assertNull(empty.firstEntry());
+        assertNull(empty.lastEntry());
+        try {
+            empty.entrySet().iterator().next();
+            fail();
+        } catch (NoSuchElementException e) {
+            // ok
+        }
+        try {
+            empty.keySet().iterator().next();
+            fail();
+        } catch (NoSuchElementException e) {
+            // ok
+        }
+        try {
+            empty.values().iterator().next();
+            fail();
+        } catch (NoSuchElementException e) {
+            // ok
+        }
+    }
 }
diff --git a/tests/src/test/java/org/teavm/classlib/java/util/TreeSetTest.java b/tests/src/test/java/org/teavm/classlib/java/util/TreeSetTest.java
new file mode 100644
index 000000000..365b8e1ae
--- /dev/null
+++ b/tests/src/test/java/org/teavm/classlib/java/util/TreeSetTest.java
@@ -0,0 +1,201 @@
+/*
+ *  Copyright 2023 ihromant.
+ *
+ *  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 static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+import java.util.Iterator;
+import java.util.List;
+import java.util.NoSuchElementException;
+import java.util.SortedSet;
+import java.util.TreeSet;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.teavm.junit.TeaVMTestRunner;
+
+@RunWith(TeaVMTestRunner.class)
+public class TreeSetTest {
+    @Test
+    public void testSortedSetReadOnly() {
+        SortedSet<String> set = new TreeSet<>(List.of("1", "2", "3", "4", "5", "6"));
+        SortedSet<String> reversed = set.reversed();
+        Iterator<String> it = reversed.iterator();
+        assertEquals("6", it.next());
+        assertEquals("5", it.next());
+        assertEquals("6", reversed.getFirst());
+        assertEquals("1", reversed.getLast());
+        SortedSet<String> subset = reversed.subSet("3", "1");
+        it = subset.iterator();
+        assertTrue(it.hasNext());
+        assertEquals("3", it.next());
+        assertTrue(it.hasNext());
+        assertEquals("2", it.next());
+        try {
+            assertFalse(it.hasNext());
+            it.next();
+            fail();
+        } catch (NoSuchElementException e) {
+            // ok
+        }
+        subset = reversed.headSet("4");
+        it = subset.iterator();
+        assertTrue(it.hasNext());
+        assertEquals("6", it.next());
+        assertTrue(it.hasNext());
+        assertEquals("5", it.next());
+        try {
+            assertFalse(it.hasNext());
+            it.next();
+            fail();
+        } catch (NoSuchElementException e) {
+            // ok
+        }
+        subset = reversed.tailSet("2");
+        it = subset.iterator();
+        assertTrue(it.hasNext());
+        assertEquals("2", it.next());
+        assertTrue(it.hasNext());
+        assertEquals("1", it.next());
+        try {
+            assertFalse(it.hasNext());
+            it.next();
+            fail();
+        } catch (NoSuchElementException e) {
+            // ok
+        }
+    }
+
+    @Test
+    public void testSequencedCollectionIterator() {
+        SortedSet<String> set = new TreeSet<>(List.of("a", "b", "c", "d")).reversed();
+        Iterator<String> it = set.iterator();
+        assertEquals("d", it.next());
+        assertEquals("c", it.next());
+        it.remove();
+        assertArrayEquals(new String[] { "d", "b", "a" }, set.toArray());
+        set = new TreeSet<>(List.of("a", "b", "c", "d")).reversed();
+        it = set.iterator();
+        assertEquals("d", it.next());
+        assertEquals("c", it.next());
+        it.remove();
+        assertEquals("b", it.next());
+        it.remove();
+        assertEquals("a", it.next());
+        try {
+            it.next();
+            fail();
+        } catch (NoSuchElementException e) {
+            // ok
+        }
+        assertArrayEquals(new String[] { "d", "a" }, set.toArray());
+    }
+
+    @Test
+    public void sequenceCollectionMethodsOnEmpty() {
+        var empty = new TreeSet<>();
+
+        try {
+            empty.getFirst();
+            fail();
+        } catch (NoSuchElementException e) {
+            // ok
+        }
+        try {
+            empty.getLast();
+            fail();
+        } catch (NoSuchElementException e) {
+            // ok
+        }
+
+        try {
+            empty.removeFirst();
+            fail();
+        } catch (NoSuchElementException e) {
+            // ok
+        }
+        try {
+            empty.removeLast();
+            fail();
+        } catch (NoSuchElementException e) {
+            // ok
+        }
+        try {
+            empty.addFirst("r");
+            fail();
+        } catch (UnsupportedOperationException e) {
+            // ok
+        }
+        try {
+            empty.addLast("r");
+            fail();
+        } catch (UnsupportedOperationException e) {
+            // ok
+        }
+    }
+
+    @Test
+    public void testMutationsIterator() {
+        SortedSet<String> set = new TreeSet<>(List.of("a", "b", "c", "d"));
+        set.add("e");
+        set.add("f");
+        Iterator<String> it = set.iterator();
+        assertEquals("a", it.next());
+        it.remove();
+        assertEquals("b", it.next());
+        it.remove();
+        assertEquals("c", it.next());
+        it.remove();
+        assertEquals("d", it.next());
+        it.remove();
+        assertEquals("e", it.next());
+        it.remove();
+        assertEquals("f", it.next());
+        it.remove();
+        assertTrue(set.isEmpty());
+        try {
+            it.next();
+            fail();
+        } catch (NoSuchElementException e) {
+            // ok
+        }
+        set = new TreeSet<>(List.of("a", "b", "c", "d"));
+        set.add("e");
+        set.add("f");
+        it = set.reversed().iterator();
+        assertEquals("f", it.next());
+        it.remove();
+        assertEquals("e", it.next());
+        it.remove();
+        assertEquals("d", it.next());
+        it.remove();
+        assertEquals("c", it.next());
+        it.remove();
+        assertEquals("b", it.next());
+        it.remove();
+        assertEquals("a", it.next());
+        it.remove();
+        assertTrue(set.isEmpty());
+        try {
+            it.next();
+            fail();
+        } catch (NoSuchElementException e) {
+            // ok
+        }
+    }
+}