@Override
  protected SortedMap<String, String> makeEmptyMap() {
    return transformValues(Maps.<String, String>newTreeMap(), Functions.<String>identity());
  }

  @Override
  protected SortedMap<String, String> makePopulatedMap() {
    SortedMap<String, Integer> underlying = Maps.newTreeMap();
    underlying.put("a", 1);
    underlying.put("b", 2);
    underlying.put("c", 3);

     * @param <V> the value type of {@link TreeMap}
     * @return a new instance of {@link TreeMap}
     * @see TreeMap#TreeMap()
     */
    public static <K, V> TreeMap<K, V> newTreeMap() {
        return new TreeMap<>();
    }

    /**
     * Creates and returns a new instance of {@link TreeMap}.
     *
     * @param <K> the key type of {@link TreeMap}

    Comparator<? super K> comparator = orNaturalOrder(left.comparator());
    SortedMap<K, V> onlyOnLeft = newTreeMap(comparator);
    SortedMap<K, V> onlyOnRight = newTreeMap(comparator);
    onlyOnRight.putAll(right); // will whittle it down
    SortedMap<K, V> onBoth = newTreeMap(comparator);
    SortedMap<K, ValueDifference<V>> differences = newTreeMap(comparator);

 */

package com.google.common.collect;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.collect.Maps.newTreeMap;
import static java.util.Collections.singletonMap;
import static java.util.Collections.unmodifiableSortedMap;

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.Comparator;

    Comparator<? super K> comparator = orNaturalOrder(left.comparator());
    SortedMap<K, V> onlyOnLeft = newTreeMap(comparator);
    SortedMap<K, V> onlyOnRight = newTreeMap(comparator);
    onlyOnRight.putAll(right); // will whittle it down
    SortedMap<K, V> onBoth = newTreeMap(comparator);
    SortedMap<K, ValueDifference<V>> differences = newTreeMap(comparator);

    TreeMap<Integer, Integer> map = Maps.newTreeMap(SOME_COMPARATOR);
    assertEquals(emptyMap(), map);
    assertThat(map.comparator()).isEqualTo(SOME_COMPARATOR);
  }

  public void testTreeMapWithInitialMap() {
    SortedMap<Integer, Integer> map = Maps.newTreeMap();
    map.put(5, 10);
    map.put(3, 20);
    map.put(1, 30);
    TreeMap<Integer, Integer> copy = Maps.newTreeMap(map);
    assertEquals(copy, map);

import org.jspecify.annotations.NullMarked;

@GwtCompatible
@NullMarked
public class FilteredSortedMapTest extends AbstractFilteredMapTest {
  @Override
  SortedMap<String, Integer> createUnfiltered() {
    return Maps.newTreeMap();
  }

  public void testFirstAndLastKeyFilteredMap() {
    SortedMap<String, Integer> unfiltered = createUnfiltered();
    unfiltered.put("apple", 2);
    unfiltered.put("banana", 6);
    unfiltered.put("cat", 3);

  public void testSameComparator() {
    assertTrue(SortedIterables.hasSameComparator(Ordering.natural(), Sets.newTreeSet()));
    assertTrue(SortedIterables.hasSameComparator(Ordering.natural(), Maps.newTreeMap().keySet()));
    assertTrue(
        SortedIterables.hasSameComparator(
            Ordering.natural().reverse(), Sets.newTreeSet(Ordering.natural().reverse())));
  }

  public void testComparator() {

    Supplier<TreeMap<Integer, Character>> factory =
        new Supplier<TreeMap<Integer, Character>>() {
          @Override
          public TreeMap<Integer, Character> get() {
            return Maps.newTreeMap();
          }
        };
    Map<String, Map<Integer, Character>> backingMap = new LinkedHashMap<>();
    Table<String, Integer, Character> table = newCustomTable(backingMap, factory);
    populate(table, data);

      NavigableMap<Cut<K>, RangeMapEntry<K, V>> entriesByLowerBound = Maps.newTreeMap();
      entriesByLowerBound.putAll(((TreeRangeMap<K, V>) rangeMap).entriesByLowerBound);
      return new TreeRangeMap<>(entriesByLowerBound);
    } else {
      NavigableMap<Cut<K>, RangeMapEntry<K, V>> entriesByLowerBound = Maps.newTreeMap();
      for (Entry<Range<K>, ? extends V> entry : rangeMap.asMapOfRanges().entrySet()) {