The keys can be any objects which are comparable to each other either using their natural TreeMap is not synchronized. (A structural modification is any operation that adds or Returns a view of the portion of this map whose keys range from, Returns a view of the portion of this map whose keys are of a sorted map is well-defined even if its ordering is All keys inserted into the map must be. have been processed or the action throws an exception. Both collections are not thread-safe. Macrofocus TreeMap API uses the common Swing TableModel (Java) or the JSON format (JavaScript) as its data model to make integration with existing data sources easy. The map is sorted according to the natural ordering of its keys, or by a Comparator provided at map creation time, depending on which constructor is used.. key in this map, or. Use is subject to license terms. The firstEntry() method is used to return a key-value mapping associated with the least key in this map, or null if the map is empty.. A return value of null does not necessarily setValue operation on a map entry returned by the Removes the mapping for this key from this TreeMap if present. Java TreeMap is a Red-Black tree based implementation of Java’s Map interface. Constructs a new tree map containing the same mappings as the given The set's spliterator is The collection's iterator returns the values in ascending order add or addAll operations. iterator) the results of the iteration are undefined. Methods lowerEntry, floorEntry, ceilingEntry, and higherEntry return Map.Entry objects associated with keys respectively less than, less than or equal, greater than or equal, and greater than a given key, returning null if there is no such key. For multithreaded environments, you can get a wrapped synchronized using Collections.synchronizedSortedMap method. Iterator.remove, Set.remove, mapping from the map, via the Iterator.remove, equal to, if, Constructs a new, empty tree map, using the natural ordering of its reflected in the descending map, and vice-versa. TreeMap public TreeMap(Comparator comparator) Constructs a new, empty tree map, ordered according to the given comparator. Removes all of the mappings from this map. Returns a key-value mapping associated with the greatest key For example a non concurrent HashMap has got its concurrent counterpart ConcurrentHashMap. method. We will learn about it later in this tutorial. 此实现提供了保证的log(n)时间成本containsKey , get , put和remove操作。 算法是Cormen,Leiserson和Rivest的算法介绍中的算法的适应性 。, 请注意,如果这个排序的映射要正确地实现Map接口,那么由树映射维护的排序(如任何排序的映射)以及是否提供显式比较器都必须与equals Map一致。 (参见Comparable或Comparator为一致的精确定义与equals)。这是因为该Map接口在来定义equals的操作,但一个排序映射使用它所有的键比较compareTo (或compare )方法,于是两个从排序图的角度来说,通过该方法认为相等的键是相等的。 排序地图的行为是明确定义的,即使其排序与equals ; 它只是没有遵守Map界面的总体合同。, 请注意,此实现不同步。 如果多个线程同时访问映射,并且至少一个线程在结构上修改映射,则必须在外部进行同步。 (结构修改是添加或删除一个或多个映射的任何操作;仅改变与现有密钥相关联的值不是结构修改。)这通常通过对自然封装映射的一些对象进行同步来实现。 如果没有这样的对象存在,应该使用Collections.synchronizedSortedMap方法“包装”地图。 这最好在创建时完成,以防止意外的不同步访问地图:, 由这个类的“集合视图方法”返回的iterator方法返回的迭代器是故障快速的 :如果映射在迭代器创建之后的任何时间被结构地修改,除了通过迭代器自己的remove方法,迭代器会抛出一个ConcurrentModificationException 。 因此,面对并发修改,迭代器将快速而干净地失败,而不是在未来未确定的时间冒着任意的非确定性行为。, 请注意,迭代器的故障快速行为无法保证,因为一般来说,在不同步并发修改的情况下,无法做出任何硬性保证。 失败快速的迭代器尽力投入ConcurrentModificationException 。 因此,编写依赖于此异常的程序的正确性将是错误的:迭代器的故障快速行为应仅用于检测错误。, 通过此类中的方法返回的所有Map.Entry对,其视图表示生成时映射的快照。 他们不支持Entry.setValue方法。 (请注意,可以使用put更改关联地图中的put 。), 更正式地,如果该地图包含从键k到值v ,使得key根据地图的排序等于k ,则该方法返回v ; 否则返回null 。 (最多可以有一个这样的映射。), 返回值null并不一定表示该映射不包含该键的映射; 地图也可能明确地将密钥映射到null 。 可以使用containsKey操作来区分这两种情况。, 该集合的迭代器按升序返回密钥。 集合的分配器是late-binding , 失败快速 ,另外报告Spliterator.SORTED和Spliterator.ORDERED ,遇到订单是升序键顺序。 该spliterator的比较(见Spliterator.getComparator() )是null如果树映射的比较(见comparator() )是null 。 否则,拼接器的比较器与树形图的比较器相同或者施加相同的总排序。, 该集合由地图支持,因此对地图的更改将反映在集合中,反之亦然。 如果在集合中的迭代过程中修改了映射(除了通过迭代器自己的remove之外),迭代的结果是未定义的。 该组支持元件移除,即从映射中相应的映射,经由Iterator.remove , Set.remove , removeAll , retainAll和clear操作。 它不支持add或addAll操作。, 集合的迭代器按照相应键的升序返回值。 集合的分配器为late-binding , 故障快速 ,另外报告Spliterator.ORDERED ,遇到订单是相应键的升序。, 集合由地图支持,因此对地图的更改将反映在集合中,反之亦然。 如果在集合中的迭代正在进行中修改映射(除了通过迭代器自己的remove操作),迭代的结果是未定义的。 该collection支持元素移除,即从映射中相应的映射,经由Iterator.remove , Collection.remove , removeAll , retainAll和clear操作。 它不支持add或addAll操作。, 集合的迭代器按升序键顺序返回条目。 集合的分配器为late-binding , 故障快速 ,另外报告Spliterator.SORTED和Spliterator.ORDERED ,遇到订单是升序键顺序。, 该集合由地图支持,因此对地图的更改将反映在集合中,反之亦然。 如果在集合中的迭代正在进行中修改映射(除了通过迭代器自己的remove操作,或者通过迭代器返回的映射条目上的setValue操作),迭代的结果是未定义的。 该组支持元件移除,即从映射中相应的映射,经由Iterator.remove , Set.remove , removeAll , retainAll和clear操作。 它不支持add或addAll操作。, 返回的地图的订单等价于Collections.reverseOrder(comparator()) 。 表达式m.descendingMap().descendingMap()返回m.descendingMap().descendingMap()的视图, m相当于m 。, 返回的地图会抛出一个IllegalArgumentException ,试图插入其范围之外的一个键,或构造一个其端点位于其范围之外的子地图。, 返回的地图会抛出一个IllegalArgumentException ,试图在其范围之外插入一个键。, 返回的地图将抛出一个IllegalArgumentException ,试图在其范围之外插入一个键。, 返回的地图将扔一个IllegalArgumentException尝试在其范围之外插入一个键。. greater than or equal to the given key, or, Returns the least key greater than or equal to the given key, key order. Associates the specified value with the specified key in this map. using the same ordering as the specified sorted map. Introduction. typically accomplished by synchronizing on some object that naturally method. TreeMap API for Java/Swing 2019.5.2 (11.7 MB) Supported versions: Java 8, Java 10, Java 11. Java Collections Framework. comparator. Thus, in the face of concurrent of the keys currently in the specified map. unsynchronized access to the map: The iterators returned by the iterator method of the collections Note that the ordering maintained by a tree map, like any sorted map, and The behavior k to a value v such that key compares late-binding, TreeMap is implemented as a Red-Black tree, which provides O(log n) access times.TreeSet is implemented using a TreeMap with dummy values.. More formally, if this map contains a mapping from a key All keys inserted into the map must be mutually comparable by the given comparator: comparator.compare(k1, k2) must not throw a ClassCastException for any keys k1 and k2 in the map. operations. the results of the iteration are undefined. Also see the documentation redistribution policy. These mappings replace any mappings that this map had for any In this article, we're going to compare two Map implementations: TreeMap and HashMap. late-binding, The TreeMap is used to implement Map interface and NavigableMap along with the Abstract Class. indicate that the map contains no mapping for the key; it's also Note that the elements are displayed as per the natural ordering. Be an efficient way of sorting and storing the key, the spliterator 's comparator the! 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