How to use

ForwardingNavigableMap

in

com.google.common.collect

/**
 * A sensible definition of {@link #ceilingKey} in terms of {@code ceilingEntry}. If you override
 * {@code ceilingEntry}, you may wish to override {@code ceilingKey} to forward to this
 * implementation.
 */
protected K standardCeilingKey(K key) {
 return keyOrNull(ceilingEntry(key));
}

@Override
public K lowerKey(K key) {
 return delegate().lowerKey(key);
}

/**
 * A sensible definition of {@link #lastEntry} in terms of the {@code iterator()} of the {@link
 * #entrySet} of {@link #descendingMap}. If you override {@code descendingMap}, you may wish to
 * override {@code lastEntry} to forward to this implementation.
 */
protected Entry<K, V> standardLastEntry() {
 return Iterables.getFirst(descendingMap().entrySet(), null);
}

/**
 * A sensible definition of {@link #lowerKey} in terms of {@code lowerEntry}. If you override
 * {@link #lowerEntry}, you may wish to override {@code lowerKey} to forward to this
 * implementation.
 */
protected K standardLowerKey(K key) {
 return keyOrNull(lowerEntry(key));
}

/**
 * A sensible definition of {@link #higherKey} in terms of {@code higherEntry}. If you override
 * {@code higherEntry}, you may wish to override {@code higherKey} to forward to this
 * implementation.
 */
protected K standardHigherKey(K key) {
 return keyOrNull(higherEntry(key));
}

/**
 * A sensible definition of {@link #floorKey} in terms of {@code floorEntry}. If you override
 * {@code floorEntry}, you may wish to override {@code floorKey} to forward to this
 * implementation.
 */
protected K standardFloorKey(K key) {
 return keyOrNull(floorEntry(key));
}

/**
 * A sensible definition of {@link #firstEntry} in terms of the {@code iterator()} of {@link
 * #entrySet}. If you override {@code entrySet}, you may wish to override {@code firstEntry} to
 * forward to this implementation.
 */
protected Entry<K, V> standardFirstEntry() {
 return Iterables.getFirst(entrySet(), null);
}

/**
 * A sensible definition of {@link #headMap(Object)} in terms of {@link #headMap(Object,
 * boolean)}. If you override {@code headMap(K, boolean)}, you may wish to override {@code
 * headMap} to forward to this implementation.
 */
protected SortedMap<K, V> standardHeadMap(K toKey) {
 return headMap(toKey, false);
}

/**
 * A sensible definition of {@link #lastKey} in terms of {@code lastEntry}. If you override {@code
 * lastEntry}, you may wish to override {@code lastKey} to forward to this implementation.
 */
protected K standardLastKey() {
 Entry<K, V> entry = lastEntry();
 if (entry == null) {
  throw new NoSuchElementException();
 } else {
  return entry.getKey();
 }
}

/**
 * A sensible definition of {@link #firstKey} in terms of {@code firstEntry}. If you override
 * {@code firstEntry}, you may wish to override {@code firstKey} to forward to this
 * implementation.
 */
protected K standardFirstKey() {
 Entry<K, V> entry = firstEntry();
 if (entry == null) {
  throw new NoSuchElementException();
 } else {
  return entry.getKey();
 }
}

/**
 * A sensible definition of {@link #lowerKey} in terms of {@code lowerEntry}. If you override
 * {@link #lowerEntry}, you may wish to override {@code lowerKey} to forward to this
 * implementation.
 */
protected K standardLowerKey(K key) {
 return keyOrNull(lowerEntry(key));
}

/**
 * A sensible definition of {@link #higherKey} in terms of {@code higherEntry}. If you override
 * {@code higherEntry}, you may wish to override {@code higherKey} to forward to this
 * implementation.
 */
protected K standardHigherKey(K key) {
 return keyOrNull(higherEntry(key));
}

/**
 * A sensible definition of {@link #floorKey} in terms of {@code floorEntry}. If you override
 * {@code floorEntry}, you may wish to override {@code floorKey} to forward to this
 * implementation.
 */
protected K standardFloorKey(K key) {
 return keyOrNull(floorEntry(key));
}

/**
 * A sensible definition of {@link #firstEntry} in terms of the {@code iterator()} of {@link
 * #entrySet}. If you override {@code entrySet}, you may wish to override {@code firstEntry} to
 * forward to this implementation.
 */
protected Entry<K, V> standardFirstEntry() {
 return Iterables.getFirst(entrySet(), null);
}

/**
 * A sensible definition of {@link #headMap(Object)} in terms of {@link #headMap(Object,
 * boolean)}. If you override {@code headMap(K, boolean)}, you may wish to override {@code
 * headMap} to forward to this implementation.
 */
protected SortedMap<K, V> standardHeadMap(K toKey) {
 return headMap(toKey, false);
}

/**
 * A sensible definition of {@link #lastKey} in terms of {@code lastEntry}. If you override {@code
 * lastEntry}, you may wish to override {@code lastKey} to forward to this implementation.
 */
protected K standardLastKey() {
 Entry<K, V> entry = lastEntry();
 if (entry == null) {
  throw new NoSuchElementException();
 } else {
  return entry.getKey();
 }
}

/**
 * A sensible definition of {@link #firstKey} in terms of {@code firstEntry}. If you override
 * {@code firstEntry}, you may wish to override {@code firstKey} to forward to this
 * implementation.
 */
protected K standardFirstKey() {
 Entry<K, V> entry = firstEntry();
 if (entry == null) {
  throw new NoSuchElementException();
 } else {
  return entry.getKey();
 }
}

/**
 * A sensible definition of {@link #pollFirstEntry} in terms of the {@code iterator} of the {@code
 * entrySet} of {@code descendingMap}. If you override {@code descendingMap}, you may wish to
 * override {@code pollFirstEntry} to forward to this implementation.
 */
protected Entry<K, V> standardPollLastEntry() {
 return Iterators.pollNext(descendingMap().entrySet().iterator());
}

/**
 * A sensible definition of {@link #ceilingKey} in terms of {@code ceilingEntry}. If you override
 * {@code ceilingEntry}, you may wish to override {@code ceilingKey} to forward to this
 * implementation.
 */
protected K standardCeilingKey(K key) {
 return keyOrNull(ceilingEntry(key));
}

/**
 * A sensible definition of {@link #lowerKey} in terms of {@code lowerEntry}. If you override
 * {@link #lowerEntry}, you may wish to override {@code lowerKey} to forward to this
 * implementation.
 */
protected K standardLowerKey(K key) {
 return keyOrNull(lowerEntry(key));
}