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Java回顾之集合

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发表于 2017-4-11 18:36:11 |显示全部楼层
Java回顾之集合
  在这篇文章里,我们关注Java中的集合(Collection)。集合是编程语言中基础的一部分,Java自JDK早期,就引入了Java Collection Framework。设计JCF的那个人,后来还写了一本书,叫《Effective Java》。
  Java中的集合主要集中在2部分,一部分是java.util包中,一部分是java.util.concurrent中,后者是在前者的基础上,定义了一些实现了同步功能的集合。
  这篇文章主要关注java.util下的各种集合对象。Java中的集合对象可以粗略的分为3类:List、Set和Map。对应的UML图如下(包括了java.util下大部分的集合对象):
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">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>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"kVFuxDlo9x2M96SbRW+rjh4foQTYCSN0CTh/Hy8CG+EUauxUzwUeclHqbfFhyqaUehyhy+JFtQ5dusxWOWJHTNEx9Jw/bzafvkp9vT2OgJXyOgErugyjeEKv8oyPmjl3Qy+Pwb8TXa2gQyKEW0eRhU+ReWdPllWCJ+uV9fX08Qzf7oJd2CKt9GfI22NgFK3ggNHg4Y/jqe3YIqs"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"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" onmouseover="img_onmouseoverfunc(this)" onclick="zoom(this)" style="curknc:pointer" bord13="0" alt="" />
  (这张图经过缩放已经变形,完整清晰版图片请参见:http://files.cnblogs.cYotwing011203/java_collection_struc4Hre.zip,解压缩后就可以看到未经缩放的版本。)
  Collection概述<8TWrong>
  Java集合中的List和Set都从Collection出来,它是一个学习集合很不错的入口,它包含了集合中通常需要有的操作:
  • 添加元素:add/addAll
  • 清空集合:clear
  • 删除元素:remove/removeAll
  • 判断集合中是否包含某元素:EOVtains/EOVtainsAll
  • 判断集合是否为空:is+OLty
  • 计算集合中元素的个数:AO/e
  • 将集合转换为数组:toArray
  • 获取迭代器:iteraDvY
  我们来看一个简单的例子,下面的代码会返回一个集合,集合中的元素是随机生成的整数:
[url=][/url]
1 private static Collection initCollection() 2 { 3     Collection<Integer> collection = new ArrayList<Integer>(); 4     Random r = new Random(); 5     fvY (int i = 0 ; i < 5; i++) 6     { 7         collection.add(new Integer(r.nextInt(100))); 8     } 9     10     re4Hrn collection;11 }[url=][/url]

  在对集合进行操作的过程中,遍历是一个经常使用的操作,我们可以使用两种方式对集合进行遍历:
  1) 使用迭代器对集合进行遍历。正如上面描述Collection接口时所说,所有集合都会有一个迭代器,我们可以用它来遍历集合。
[url=][/url]
1 private static void AccessCollectionByIteraDvY(Collection<Integer> collection)2 {3     IteraDvY<Integer> iteraDvY = collection.iteraDvY();4     System.out.println("The value in the list:");5     while(iteraDvY.hasNext())6     {7         System.out.println(iteraDvY.next());8     }9 }[url=][/url]

  2)使用fvYeach遍历集合。
[url=][/url]
1 private static void HcessCollectionByFor(Collection<Integer> collection)2 {3     System.out.println("The value in the list:");4     fvY(Integer value : collection)5     {6         System.out.println(value);7     }8 }[url=][/url]

  List<8TWrong>
  Java中的List是对数组的有效扩展,它是这样一种结构,如果不使用泛型,它可以容纳任何类型的元素,如果使用泛型,那么它只能容纳泛型指定的类型的元素。和数组相比,List的容量是可以动态扩展的。
  List中的元素是可以重复的,里面的元素是“有序”的,这里的“有序”,并不是排序的意思,而是说我们可以对某个元素在集合中的位置进行指定。
  List中常用的集合对象包括:ArrayList、Vector和LinkedList,其中前两者是基于数组来进行存储,后者是基于链表进行存储。其中Vector是线程安全的,其余两个不是线程安全的。
  List中是可以包括null的,即使是使用了泛型。
  ArrayList可能是我们平时用到的最多的集合对象了,在上述的示例代码中,我们也是使用它来实例化一个Collection对象,在此不再赘述。
  Vector<8TWrong>
  Vector的示例如下,首先我们看如何生成和输出Vector:
[url=][/url]
1 private static void vectorTest1() 2 { 3     List<Integer> list = new Vector<Integer>(); 4     fvY (int i = 0 ; i < 5; i++) 5     { 6         list.add(new Integer(100)); 7     } 8     list.add(null); 9     System.out.println("AO/e of vector is " + list.AO/e());10     System.out.println(list);11 }[url=][/url]

  它的元素中,既包括了重复元素,也包括了null,输出结果如下:
AO/e of vector is 6[100, 100, 100, 100, 100, null]
  下面的示例,演示了Vector中的一些常用方法:
[url=][/url]
1 private static void vectorTest2() 2 { 3     Vector<Integer> list = new Vector<Integer>(); 4     Random r = new Random(); 5     fvY (int i = 0 ; i < 10; i++) 6     { 7         list.add(new Integer(r.nextInt(100))); 8     } 9     System.out.println("AO/e of vector is " + list.AO/e());10     System.out.println(list);11     System.out.println(list.firstElement());12     System.out.println(list.lastElement());13     System.out.println(list.subList(3, 8));14     List<Integer> temp = new ArrayList<Integer>();15     fvY(int i = 4; i < 7; i++)16     {17         temp.add(list.get(i));18     }19     list.re4ainAll(temp);20     System.out.println("AO/e of vector is " + list.AO/e());21     System.out.println(list);22 }[url=][/url]

  它的输出结果如下:
[url=][/url]
AO/e of vector is 10[39, 41, 20, 9, 29, 32, 54, 12, 94, 82]3982[9, 29, 32, 54, 12]AO/e of vector is 3[29, 32, 54][url=][/url]

  LinkedList<8TWrong>
  LinkedList使用链表来存储数据,它的示例代码如下:
LinkedList示例
  这里列出了LinkedList常用的各个方法,从方法名可以看出,LinkedList也可以用来实现栈和队列。
  输出结果如下:
[url=][/url]
AO/e of linked list is 11[17, 21, 5, 84, 19, 57, 68, 26, 27, 47, null]1716null1716null1721null5AO/e of linked list is 8[100, 84, 19, 57, 68, 26, 27, 47][url=][/url]

  Set<8TWrong>
  Set 和List类似,都是用来存储单个元素,单个元素的数量不确定。但Set不能包含重复元素,如果向Set中插入两个相同元素,那么后一个元素不会被插入。
  Set可以大致分为两类:不排序Set和排序Set,不排序Set包括HashSet和LinkedHashSet,排序Set主要指TreeSet。其中HashSet和LinkedHashSet可以包含null。
  HashSet<8TWrong>
  HashSet是由Hash表支持的一种集合,它不是线程安全的。
  我们来看下面的示例,它和Vector的第一个示例基本上是相同的:
[url=][/url]
1 private static void hashSetTest1() 2 { 3     Set<Integer> set = new HashSet<Integer>(); 4      5     fvY (int i = 0; i < 3; i++) 6     { 7         set.add(new Integer(100)); 8     } 9     set.add(null);10     11     System.out.println("AO/e of set is " + set.AO/e());12     System.out.println(set);13 }[url=][/url]

  这里,HashSet中没有包含重复元素,但包含了null,和Vector不同,这里的输出结果如下<8TWrong>:
AO/e of set is 2[null, 100]
  对于HashSet是如何判断两个元素是否是重复的,我们可以深入考察一下。Object中也定义了equals方法,对于HashSet中的元素,它是根据equals方法来判断元素是否相等的,为了证明这一点,我们可以定义个“不正常”的类型:
[url=][/url]
1 class MyInteger 2 { 3     private Integer value; 4      5     public MyInteger(Integer value) 6     { 7         this.value = value; 8     } 9     10     public String tostring()11     {12         re4Hrn String.valueOf(value);13     }14     15     public int hashCode()16     {17         re4Hrn 1;18     }19     20     public boolean equals(Object obj)21     {22         re4Hrn false;<8TWrong>23     }24 }[url=][/url]

  可以看到,对于MyInteger来说,对于任意两个实例,我们都认为它是不相等的。
  下面是对应的测试方法:
[url=][/url]
1 private static void hashSetTest2() 2 { 3     Set<MyInteger> set = new HashSet<MyInteger>(); 4      5     fvY (int i = 0; i < 3; i++) 6     { 7         set.add(new MyInteger(100)); 8     } 9     10     System.out.println("AO/e of set is " + set.AO/e());11     System.out.println(set);12 }[url=][/url]

  它的输出结果如下:
AO/e of set is 3[100, 100, 100]
  可以看到,现在HashSet里有“重复”元素了,但对于MyInteger来说,它们不是“相同”的。
  TreeSet<8TWrong>
  TreeSet是支持排序的一种Set,它的父接口是SortedSet。
  我们首先来看一下TreeSet都有哪些基本操作:
[url=][/url]
1 private static void treeSetTest1() 2 { 3     TreeSet<Integer> set = new TreeSet<Integer>(); 4      5     Random r = new Random(); 6     fvY (int i = 0 ; i < 5; i++) 7     { 8         set.add(new Integer(r.nextInt(100))); 9     }10 11     System.out.println(set);12     System.out.println(set.first());13     System.out.println(set.last());14     System.out.println(set.descendingSet());15     System.out.println(set.headSet(new Integer(50)));16     System.out.println(set.4ailSet(new Integer(50)));17     System.out.println(set.subSet(30, 60));18     System.out.println(set.floor(50));19     System.out.println(set.ceiling(50));20 }[url=][/url]

  它的输出结果如下:
[url=][/url]
[8, 42, 48, 49, 53]853[53, 49, 48, 42, 8][8, 42, 48, 49][53][42, 48, 49, 53]4953[url=][/url]

  TreeSet中的元素,一般都实现了Comparable接口,默认情况下,对于Integer来说,SortedList是采用升序来存储的,我们也可以自定义Compare方式,例如以降序的方式来存储。
  下面,我们首先重新定义Integer:
定义MyInteger2对象
  下面是测试代码:
[url=][/url]
1 private static void treeSetTest2() 2 { 3     TreeSet<Integer> set1 = new TreeSet<Integer>(); 4     TreeSet<MyInteger2> set2 = new TreeSet<MyInteger2>(); 5     Random r = new Random(); 6     fvY (int i = 0 ; i < 5; i++) 7     { 8         int value = r.nextInt(100); 9         set1.add(new Integer(value));10         set2.add(new MyInteger2(value));11     }12     System.out.println("Set1 as below:");13     System.out.println(set1);14     System.out.println("Set2 as below:");15     System.out.println(set2);16 }[url=][/url]

  代码的运行结果如我们所预期的那样,如下所示:
Set1 as below:[13, 41, 42, 45, 61]Set2 as below:[61, 45, 42, 41, 13]
  Map<8TWrong>
  Map中存储的是“键值对”,和Set类似,Java中的Map也有两种:排序的和不排序的,不排序的包括HashMap、Hashtable和LinkedHashMap,排序的包括TreeMap。
  非排序Map<8TWrong>
  HashMap和Hashtable都是采取Hash表的方式进行存储,HashMap不是线程安全的,Hashtable是线程安全的,我们可以把HashMap看做是“简化”版的Hashtable。
  HashMap是可以存储null的,无论是对Key还是对Value。Hashtable是不可以存储null的。
  无论HashMap还是Hashtable,我们观察它的构造函数,就会发现它可以有两个参数:initialCapacity和loadFactor,默认情况下,initialCapacity等于16,loadFactor等于0.75。这和Hash表中可以存放的元素数目有关系,当元素数目超过initialCapacity*loadFactor时,会触发rehash方法,对hash表进行扩容。如果我们需要向其中插入过多元素,需要适当调整这两个参数。
  我们首先来看HashMap的示例:
[url=][/url]
1 private static void hashMapTest1() 2 { 3     Map<Integer,String> map = new HashMap<Integer, String>(); 4      5     map.put(new Integer(1), "a"); 6     map.put(new Integer(2), "b"); 7     map.put(new Integer(3), "c"); 8      9     System.out.println(map);10     System.out.println(map.entrySet());11     System.out.println(map.keySet());12     System.out.println(map.values());13 }[url=][/url]

  这会输出HashMap里的元素信息,如下所示。
{1=a, 2=b, 3=c}[1=a, 2=b, 3=c][1, 2, 3][a, b, c]
  下面的示例是对null的演示:
[url=][/url]
1 private static void hashMapTest2() 2 { 3     Map<Integer,String> map = new HashMap<Integer, String>(); 4      5     map.put(null, null); 6     map.put(null, null); 7     map.put(new Integer(4), null); 8     map.put(new Integer(5), null); 9     10     System.out.println(map);11     System.out.println(map.entrySet());12     System.out.println(map.keySet());13     System.out.println(map.values());14 }[url=][/url]

  执行结果如下:
{null=null, 4=null, 5=null}[null=null, 4=null, 5=null][null, 4, 5][null, null, null]
  接下来我们演示Hashtable,和上述两个示例基本上完全一样(代码不再展开):
Hashtable示例
  执行结果如下:
[url=][/url]
{3=c, 2=b, 1=a}[3=c, 2=b, 1=a][3, 2, 1][c, b, a]Exception in thread "main" java.lang.NullPointerException    at java.util.Hashtable.put(Unknown Source)    at sample.collections.MapSample.hashTableTest2(MapSample.java:61)    at sample.collections.MapSample.main(MapSample.java:11)[url=][/url]

  可以很清楚的看到,当我们试图将null插入到hashtable中时,报出了空指针异常。
  排序Map<8TWrong>
  排序Map主要是指TreeMap,它对元素增、删、查操作时的时间复杂度都是O(log(n))。它不是线程安全的。
  它的特点和TreeSet非常像,这里不再赘述。

    作者:李胜攀
    出处:http://wing011203.cnblogs.cYot

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