Java集合源码学习(21)_Map接口子接口SortedMap和NavigableMap

1：SortedMap继承自Map接口，增加了按顺序操作的几个方法;

2：排序是按照key的自然顺序(必须实现Comparable)或者指定的Comparator

Method Summary Comparator<? superK>comparator() 
          Returns the comparator used to order the keys in this map, or null if this map uses the natural ordering of its keys. Set<Map.Entry<K,V>>entrySet() 
          Returns a Set view of the mappings contained in this map. KfirstKey() 
          Returns the first (lowest) key currently in this map. SortedMap<K,V>headMap(K toKey) 
          Returns a view of the portion of this map whose keys are strictly less than toKey. Set<K>keySet() 
          Returns a Set view of the keys contained in this map. KlastKey() 
          Returns the last (highest) key currently in this map. SortedMap<K,V>subMap(K fromKey, K toKey) 
          Returns a view of the portion of this map whose keys range from fromKey, inclusive, to toKey, exclusive. SortedMap<K,V>tailMap(K fromKey) 
          Returns a view of the portion of this map whose keys are greater than or equal to fromKey. Collection<V>values() 
          Returns a Collection view of the values contained in this map.

1：NavigableMap继承了SortedMap

Method Summary Comparator<? superK>comparator() 
          Returns the comparator used to order the keys in this map, or null if this map uses the natural ordering of its keys. Set<Map.Entry<K,V>>entrySet() 
          Returns a Set view of the mappings contained in this map. KfirstKey() 
          Returns the first (lowest) key currently in this map. SortedMap<K,V>headMap(K toKey) 
          Returns a view of the portion of this map whose keys are strictly less than toKey. Set<K>keySet() 
          Returns a Set view of the keys contained in this map. KlastKey() 
          Returns the last (highest) key currently in this map. SortedMap<K,V>subMap(K fromKey, K toKey) 
          Returns a view of the portion of this map whose keys range from fromKey, inclusive, to toKey, exclusive. SortedMap<K,V>tailMap(K fromKey) 
          Returns a view of the portion of this map whose keys are greater than or equal to fromKey. Collection<V>values() 
          Returns a Collection view of the values contained in this map.


Method Summary Map.Entry<K,V>ceilingEntry(K key) 
          Returns a key-value mapping associated with the least key greater than or equal to the given key, or nullif there is no such key. KceilingKey(K key) 
          Returns the least key greater than or equal to the given key, or null if there is no such key. NavigableSet<K>descendingKeySet() 
          Returns a reverse order NavigableSet view of the keys contained in this map. NavigableMap<K,V>descendingMap() 
          Returns a reverse order view of the mappings contained in this map. Map.Entry<K,V>firstEntry() 
          Returns a key-value mapping associated with the least key in this map, or null if the map is empty. Map.Entry<K,V>floorEntry(K key) 
          Returns a key-value mapping associated with the greatest key less than or equal to the given key, or nullif there is no such key. KfloorKey(K key) 
          Returns the greatest key less than or equal to the given key, or null if there is no such key. SortedMap<K,V>headMap(K toKey) 
          Returns a view of the portion of this map whose keys are strictly less than toKey. NavigableMap<K,V>headMap(K toKey, boolean inclusive) 
          Returns a view of the portion of this map whose keys are less than (or equal to, if inclusive is true)toKey. Map.Entry<K,V>higherEntry(K key) 
          Returns a key-value mapping associated with the least key strictly greater than the given key, or null if there is no such key. KhigherKey(K key) 
          Returns the least key strictly greater than the given key, or null if there is no such key. Map.Entry<K,V>lastEntry() 
          Returns a key-value mapping associated with the greatest key in this map, or null if the map is empty. Map.Entry<K,V>lowerEntry(K key) 
          Returns a key-value mapping associated with the greatest key strictly less than the given key, or null if there is no such key. KlowerKey(K key) 
          Returns the greatest key strictly less than the given key, or null if there is no such key. NavigableSet<K>navigableKeySet() 
          Returns a NavigableSet view of the keys contained in this map. Map.Entry<K,V>pollFirstEntry() 
          Removes and returns a key-value mapping associated with the least key in this map, or null if the map is empty. Map.Entry<K,V>pollLastEntry() 
          Removes and returns a key-value mapping associated with the greatest key in this map, or null if the map is empty. NavigableMap<K,V>subMap(K fromKey, boolean fromInclusive, K toKey, boolean toInclusive) 
          Returns a view of the portion of this map whose keys range from fromKey to toKey. SortedMap<K,V>subMap(K fromKey, K toKey) 
          Returns a view of the portion of this map whose keys range from fromKey, inclusive, to toKey, exclusive. SortedMap<K,V>tailMap(K fromKey) 
          Returns a view of the portion of this map whose keys are greater than or equal to fromKey. NavigableMap<K,V>tailMap(K fromKey, boolean inclusive) 
          Returns a view of the portion of this map whose keys are greater than (or equal to, if inclusive is true)fromKey.

Method Summary Comparator<? superK>comparator() 
          Returns the comparator used to order the keys in this map, or null if this map uses the natural ordering of its keys. Set<Map.Entry<K,V>>entrySet() 
          Returns a Set view of the mappings contained in this map. KfirstKey() 
          Returns the first (lowest) key currently in this map. SortedMap<K,V>headMap(K toKey) 
          Returns a view of the portion of this map whose keys are strictly less than toKey. Set<K>keySet() 
          Returns a Set view of the keys contained in this map. KlastKey() 
          Returns the last (highest) key currently in this map. SortedMap<K,V>subMap(K fromKey, K toKey) 
          Returns a view of the portion of this map whose keys range from fromKey, inclusive, to toKey, exclusive. SortedMap<K,V>tailMap(K fromKey) 
          Returns a view of the portion of this map whose keys are greater than or equal to fromKey. Collection<V>values() 
          Returns a Collection view of the values contained in this map.

Method Summary Map.Entry<K,V>ceilingEntry(K key) 
          Returns a key-value mapping associated with the least key greater than or equal to the given key, or nullif there is no such key. KceilingKey(K key) 
          Returns the least key greater than or equal to the given key, or null if there is no such key. NavigableSet<K>descendingKeySet() 
          Returns a reverse order NavigableSet view of the keys contained in this map. NavigableMap<K,V>descendingMap() 
          Returns a reverse order view of the mappings contained in this map. Map.Entry<K,V>firstEntry() 
          Returns a key-value mapping associated with the least key in this map, or null if the map is empty. Map.Entry<K,V>floorEntry(K key) 
          Returns a key-value mapping associated with the greatest key less than or equal to the given key, or nullif there is no such key. KfloorKey(K key) 
          Returns the greatest key less than or equal to the given key, or null if there is no such key. SortedMap<K,V>headMap(K toKey) 
          Returns a view of the portion of this map whose keys are strictly less than toKey. NavigableMap<K,V>headMap(K toKey, boolean inclusive) 
          Returns a view of the portion of this map whose keys are less than (or equal to, if inclusive is true)toKey. Map.Entry<K,V>higherEntry(K key) 
          Returns a key-value mapping associated with the least key strictly greater than the given key, or null if there is no such key. KhigherKey(K key) 
          Returns the least key strictly greater than the given key, or null if there is no such key. Map.Entry<K,V>lastEntry() 
          Returns a key-value mapping associated with the greatest key in this map, or null if the map is empty. Map.Entry<K,V>lowerEntry(K key) 
          Returns a key-value mapping associated with the greatest key strictly less than the given key, or null if there is no such key. KlowerKey(K key) 
          Returns the greatest key strictly less than the given key, or null if there is no such key. NavigableSet<K>navigableKeySet() 
          Returns a NavigableSet view of the keys contained in this map. Map.Entry<K,V>pollFirstEntry() 
          Removes and returns a key-value mapping associated with the least key in this map, or null if the map is empty. Map.Entry<K,V>pollLastEntry() 
          Removes and returns a key-value mapping associated with the greatest key in this map, or null if the map is empty. NavigableMap<K,V>subMap(K fromKey, boolean fromInclusive, K toKey, boolean toInclusive) 
          Returns a view of the portion of this map whose keys range from fromKey to toKey. SortedMap<K,V>subMap(K fromKey, K toKey) 
          Returns a view of the portion of this map whose keys range from fromKey, inclusive, to toKey, exclusive. SortedMap<K,V>tailMap(K fromKey) 
          Returns a view of the portion of this map whose keys are greater than or equal to fromKey. NavigableMap<K,V>tailMap(K fromKey, boolean inclusive) 
          Returns a view of the portion of this map whose keys are greater than (or equal to, if inclusive is true)fromKey.