java容器 接口NavigableMap源码分析
目录
简介
lowerXXX,floorXXX,ceilingXXX,higherXXX，总共8个
firstEntry,lastEntry,pollFirstEntry,pollLastEntry
subMap,tailMap,headMap，每个2个
简介
/**
* 一个SortedMap扩展了navigation方法，为给定的搜索目标返回最接近的匹配。
* 方法lowerEntry, floorEntry, ceilingEntry, 和 higherEntry返回
* Map.Entry对象，分别与小于、小于或等于、大于或等于、大于给定键关联的条目对象，如果没有这样的键，则返回null。
* 类似地，方法lowerKey、floorKey、ceilingKey和higherKey只返回关联的键。所有这些方法都是为定位而设计的，而不是遍历条目。
*
* 可按升序或降序键顺序访问和遍历NavigableMap。
* descendingMap方法返回映射的一个视图，该视图具有所有反向的关系和反转方向的方法。
* ascending操作和视图的性能可能比descending操作和视图的性能更快。
* 方法subMap、headMap和tailMap与类似名称的SortedMap方法不同，它们接受额外的参数来描述下界和上界是包含的还是排他的。
* 任何NavigableMap的子映射都必须实现NavigableMap接口。
*
*
该接口还定义了firstEntry、pollFirstEntry、lastEntry和pollLastEntry方法，
* 这些方法返回和/或删除最小和最大的映射(如果存在的话)，否则返回null。
*
*
返回entry方法的实现应该返回Map.Entry对，表示生成映射时的快照，因此通常不支持可选的setValue方法。
* 但是请注意，可以使用put方法更改关联映射中的映射。
*
*
方法subMap(K, K)、headMap(K)和tailMap(K)被指定为返回SortedMap，
* 以允许对SortedMap的现有实现进行兼容的改进以实现NavigableMap，但是这个接口的扩展和实现被鼓励重写这些方法以返回NavigableMap。
* 类似地，可以覆盖keySet()来返回NavigableSet。
*
*
* @author Doug Lea
* @author Josh Bloch
* @param the type of keys maintained by this map
* @param the type of mapped values
* @since 1.6
*/
public interface NavigableMap extends SortedMap
lowerXXX,floorXXX,ceilingXXX,higherXXX，总共8个
/**
* 返回严格小于给定键的与最大键关联的键-值映射，如果没有这样的键，则返回null。
*
* @param key the key
* @return an entry with the greatest key less than {@code key},
* or {@code null} if there is no such key
* @throws ClassCastException if the specified key cannot be compared
* with the keys currently in the map
* @throws NullPointerException if the specified key is null
* and this map does not permit null keys
*/
Map.Entry lowerEntry(K key);
/**
* 返回严格小于给定键的最大键，如果没有这样的键，则返回null。
*
* @param key the key
* @return the greatest key less than {@code key},
* or {@code null} if there is no such key
* @throws ClassCastException if the specified key cannot be compared
* with the keys currently in the map
* @throws NullPointerException if the specified key is null
* and this map does not permit null keys
*/
K lowerKey(K key);
/**
* 返回与小于或等于给定键的最大键相关联的键-值映射，如果没有这样的键，则返回null。
*
* @param key the key
* @return an entry with the greatest key less than or equal to
* {@code key}, or {@code null} if there is no such key
* @throws ClassCastException if the specified key cannot be compared
* with the keys currently in the map
* @throws NullPointerException if the specified key is null
* and this map does not permit null keys
*/
Map.Entry floorEntry(K key);
/**
* Returns the greatest key less than or equal to the given key,
* or {@code null} if there is no such key.
*
* @param key the key
* @return the greatest key less than or equal to {@code key},
* or {@code null} if there is no such key
* @throws ClassCastException if the specified key cannot be compared
* with the keys currently in the map
* @throws NullPointerException if the specified key is null
* and this map does not permit null keys
*/
K floorKey(K key);
/**
* 返回与大于或等于给定键的最小键关联的键-值映射，如果没有这样的键，则返回null。
*
* @param key the key
* @return an entry with the least key greater than or equal to
* {@code key}, or {@code null} if there is no such key
* @throws ClassCastException if the specified key cannot be compared
* with the keys currently in the map
* @throws NullPointerException if the specified key is null
* and this map does not permit null keys
*/
Map.Entry ceilingEntry(K key);
/**
* 返回大于或等于给定键的最小键，如果没有这样的键，则返回null。
*
* @param key the key
* @return the least key greater than or equal to {@code key},
* or {@code null} if there is no such key
* @throws ClassCastException if the specified key cannot be compared
* with the keys currently in the map
* @throws NullPointerException if the specified key is null
* and this map does not permit null keys
*/
K ceilingKey(K key);
/**
* 返回与严格大于给定键的最小键关联的键-值映射，如果没有这样的键，则返回null。
*
* @param key the key
* @return an entry with the least key greater than {@code key},
* or {@code null} if there is no such key
* @throws ClassCastException if the specified key cannot be compared
* with the keys currently in the map
* @throws NullPointerException if the specified key is null
* and this map does not permit null keys
*/
Map.Entry higherEntry(K key);
/**
* 返回严格大于给定键的最小键，如果没有这样的键，则返回null。
*
* @param key the key
* @return the least key greater than {@code key},
* or {@code null} if there is no such key
* @throws ClassCastException if the specified key cannot be compared
* with the keys currently in the map
* @throws NullPointerException if the specified key is null
* and this map does not permit null keys
*/
K higherKey(K key); firstEntry,lastEntry,pollFirstEntry,pollLastEntry
/**
* 返回与此映射中最小键关联的键-值映射，如果映射为空则返回null。
*
* @return an entry with the least key,
* or {@code null} if this map is empty
*/
Map.Entry firstEntry();
/**
* 返回与此映射中最大键关联的键-值映射，如果映射为空则返回null。
*
* @return an entry with the greatest key,
* or {@code null} if this map is empty
*/
Map.Entry lastEntry();
/**
* 删除并返回与此映射中最小键关联的键-值映射，如果映射为空则返回null。
*
* @return the removed first entry of this map,
* or {@code null} if this map is empty
*/
Map.Entry pollFirstEntry();
/**
* 删除并返回与此映射中最大键关联的键-值映射，如果映射为空则返回null。
*
* @return the removed last entry of this map,
* or {@code null} if this map is empty
*/
Map.Entry pollLastEntry(); descendingMap,navigableKeySet,descendingKeySet
/**
* 返回此映射中包含的映射的逆序视图。descending映射由该映射支持，因此对映射的更改反映在descending映射中，反之亦然。
* 如果在对任何一个map的集合视图进行迭代时(除了通过迭代器自己的删除操作之外)，其中一个map被修改，那么迭代的结果是未定义的。
*
* 返回的映射的顺序相当于Collections.reverseOrder(comparator())。
* 表达式{@code m.descendingMap().descendingMap()}返回一个m的视图，它本质上等价于m。
*
* @return a reverse order view of this map
*/
NavigableMap descendingMap();
/**
* 返回包含在此映射中的键的NavigableSet视图。
* 集合的迭代器按升序返回键。集合由映射支持，因此对映射的更改将反映在集合中，反之亦然。
* 如果在对集合进行迭代时修改了映射(除了通过迭代器自己的删除操作)，则迭代的结果是未定义的。
* 集合支持元素删除，它通过Iterator.remove, Set.remove, removeAll, retainAll, and clear 操作。
* 它不支持add或addAll操作。
*
* @return a navigable set view of the keys in this map
*/
NavigableSet navigableKeySet();
/**
* 返回包含在此映射中的键的逆序NavigableSet视图。
* 集合的迭代器按降序返回键。集合由映射支持，因此对映射的更改将反映在集合中，反之亦然。
* 如果在对集合进行迭代时修改了映射(除了通过迭代器自己的删除操作)，则迭代的结果是未定义的。
* 集合支持元素删除，它通过Iterator.remove, Set.remove, removeAll, retainAll, and clear 操作。
* 它不支持add或addAll操作。
*
* @return a reverse order navigable set view of the keys in this map
*/
NavigableSet descendingKeySet();
subMap,tailMap,headMap，每个2个
/**
* 返回该映射中键值范围从fromKey到toKey的部分的视图。
* 如果fromKey和toKey相等，则返回的映射为空，除非fromInclusive和toInclusive都为true。
* 返回的映射得到此映射的支持，因此返回映射中的更改将反映在此映射中，反之亦然。
* 返回的映射支持此映射支持的所有可选映射操作。
*
* 返回的映射将抛出一个IllegalArgumentException，
* 用于试图将一个键插入到它的范围之外，或者构造一个其端点位于它的范围之外的子映射。
*
* @param fromKey low endpoint of the keys in the returned map
* @param fromInclusive {@code true} if the low endpoint
* is to be included in the returned view
* @param toKey high endpoint of the keys in the returned map
* @param toInclusive {@code true} if the high endpoint
* is to be included in the returned view
* @return a view of the portion of this map whose keys range from
* {@code fromKey} to {@code toKey}
* @throws ClassCastException if {@code fromKey} and {@code toKey}
* cannot be compared to one another using this map's comparator
* (or, if the map has no comparator, using natural ordering).
* Implementations may, but are not required to, throw this
* exception if {@code fromKey} or {@code toKey}
* cannot be compared to keys currently in the map.
* @throws NullPointerException if {@code fromKey} or {@code toKey}
* is null and this map does not permit null keys
* @throws IllegalArgumentException if {@code fromKey} is greater than
* {@code toKey}; or if this map itself has a restricted
* range, and {@code fromKey} or {@code toKey} lies
* outside the bounds of the range
*/
NavigableMap subMap(K fromKey, boolean fromInclusive,
K toKey, boolean toInclusive);
/**
* 返回映射中键值小于(或等于，如果inclusive为true)toKey部分的视图。
* 返回的映射得到此映射的支持，因此返回映射中的更改将反映在此映射中，反之亦然。
* 返回的映射支持此映射支持的所有可选映射操作。
*
* 返回的映射将抛出一个IllegalArgumentException，
* 用于试图将一个键插入到它的范围之外，或者构造一个其端点位于它的范围之外的子映射。
*
* @param toKey high endpoint of the keys in the returned map
* @param inclusive {@code true} if the high endpoint
* is to be included in the returned view
* @return a view of the portion of this map whose keys are less than
* (or equal to, if {@code inclusive} is true) {@code toKey}
* @throws ClassCastException if {@code toKey} is not compatible
* with this map's comparator (or, if the map has no comparator,
* if {@code toKey} does not implement {@link Comparable}).
* Implementations may, but are not required to, throw this
* exception if {@code toKey} cannot be compared to keys
* currently in the map.
* @throws NullPointerException if {@code toKey} is null
* and this map does not permit null keys
* @throws IllegalArgumentException if this map itself has a
* restricted range, and {@code toKey} lies outside the
* bounds of the range
*/
NavigableMap headMap(K toKey, boolean inclusive);
/**
* 返回映射中键值大于(或等于，如果inclusive为true)fromKey的部分的视图。
* 返回的映射得到此映射的支持，因此返回映射中的更改将反映在此映射中，反之亦然。
* 返回的映射支持此映射支持的所有可选映射操作。
*
* 返回的映射将抛出一个IllegalArgumentException，
* 用于试图将一个键插入到它的范围之外，或者构造一个其端点位于它的范围之外的子映射。
*
* @param fromKey low endpoint of the keys in the returned map
* @param inclusive {@code true} if the low endpoint
* is to be included in the returned view
* @return a view of the portion of this map whose keys are greater than
* (or equal to, if {@code inclusive} is true) {@code fromKey}
* @throws ClassCastException if {@code fromKey} is not compatible
* with this map's comparator (or, if the map has no comparator,
* if {@code fromKey} does not implement {@link Comparable}).
* Implementations may, but are not required to, throw this
* exception if {@code fromKey} cannot be compared to keys
* currently in the map.
* @throws NullPointerException if {@code fromKey} is null
* and this map does not permit null keys
* @throws IllegalArgumentException if this map itself has a
* restricted range, and {@code fromKey} lies outside the
* bounds of the range
*/
NavigableMap tailMap(K fromKey, boolean inclusive);
/**
* {@inheritDoc}
*
* 等于 {@code subMap(fromKey, true, toKey, false)}.
*
* @throws ClassCastException {@inheritDoc}
* @throws NullPointerException {@inheritDoc}
* @throws IllegalArgumentException {@inheritDoc}
*/
SortedMap subMap(K fromKey, K toKey);
/**
* {@inheritDoc}
*
* 等于 {@code headMap(toKey, false)}.
*
* @throws ClassCastException {@inheritDoc}
* @throws NullPointerException {@inheritDoc}
* @throws IllegalArgumentException {@inheritDoc}
*/
SortedMap headMap(K toKey);
/**
* {@inheritDoc}
*
* 等于 {@code tailMap(fromKey, true)}.
*
* @throws ClassCastException {@inheritDoc}
* @throws NullPointerException {@inheritDoc}
* @throws IllegalArgumentException {@inheritDoc}
*/
SortedMap tailMap(K fromKey);