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Java里的list,set,map操作方法

來源:中華考試網(wǎng)  [2020年10月28日]  【

  //ArrayList

  {

  ArrayList arraylist=new ArrayList();

  arraylist.add(0,"end");//指定索引加入值

  //需注意的是,如果現(xiàn)有2個(gè)值,我加入索引為5的那么就會出現(xiàn)異常

  for(int i=0;i<2;i++){

  arraylist.add(i,String.valueOf(i));

  }

  System.out.println("ArrayList:");

  for(int i=0;i

  System.out.print(arraylist.get(i)+";");

  }

  arraylist.add("0");//直接加入值到ArrayList的最后

  arraylist.add("0");

  System.out.print("\nArrayList\'s lastIndexOf(\"0\") is "+arraylist.lastIndexOf("0"));

  }

  //Arrays

  {

  String []array=new String[]{"a","b","c"};

  List list=Arrays.asList(array);

  System.out.println("\nArrays:");

  for(int i=0;i

  System.out.print(list.get(i)+";");

  }

  System.out.print("\nArrays\'s length is "+array.length);//打印數(shù)組的長度

  }

  //Collections

  {

  String []array=new String[]{"a","b","c"};

  List list=Arrays.asList(array);

  Collections.fill(list,"Fill");//用Fill填充全部元素

  System.out.println("\nCollections:");

  for(int i=0;i

  System.out.print(list.get(i)+";");

  }

  array=new String[]{"1","2","3"};

  List list2=Arrays.asList(array);

  Collections.copy(list,list2);//拷貝list2的數(shù)據(jù)進(jìn)list

  System.out.println("\n"+list);

  Collections.swap(list,2,1);//調(diào)換索引為1和2的元素的位置

  System.out.println(list);

  }

  //EventObject

  {

  String s="hello";

  String s2=s;

  EventObject eventobject=new EventObject(s);//一個(gè)準(zhǔn)容器類型,確切的歸類它不是容器

  System.out.println("EventObject:");

  System.out.println(eventobject.getSource());

  System.out.println(eventobject.equals(s2));

  }

  //HashMap

  {

  HashMap hashmap=new HashMap();//一個(gè)速度最快的容器

  hashmap.put("0","c");

  hashmap.put("1","a");

  hashmap.put("2","b");

  hashmap.put("3","a");

  System.out.println("HashMap:");

  System.out.println(hashmap);//該容器有其內(nèi)部的排序方式

  Set set=hashmap.keySet();//獲取全部鍵

  Iterator iterator=set.iterator();

  while(iterator.hasNext()){

  System.out.print(hashmap.get(iterator.next())+";");

  }

  }

  //HashSet

  {

  HashSet hashset=new HashSet();//一個(gè)絕對不能重復(fù)的類型

  hashset.add("c");

  hashset.add("b");

  hashset.add("a");

  hashset.add("a");

  hashset.add("b");

  System.out.println("\nHashSet:");

  System.out.println(hashset);

  Iterator iterator=hashset.iterator();//取出元素

  while(iterator.hasNext()){

  System.out.print(iterator.next()+";");

  }

  }

  //Hashtable

  {

  Hashtable hashtable=new Hashtable();//一個(gè)完全可以由其他容器替換的老容器類型

  hashtable.put("0","c");

  hashtable.put("1","a");

  hashtable.put("3","c");

  hashtable.put("2","b");

  System.out.println("\nHashtable:");

  Enumeration enumeration=hashtable.elements();//獲取元素,Enumeration已經(jīng)不是主流,Iterator是它的下一代替代品

  while(enumeration.hasMoreElements()){

  System.out.print(enumeration.nextElement()+";");

  }

  }

  //IdentityHashMap

  {

  IdentityHashMap identityhashmap=new IdentityHashMap();

  identityhashmap.put("0","c");

  identityhashmap.put("1","a");

  identityhashmap.put("3","b");

  identityhashmap.put("2","a");

  System.out.println("\nIdentityHashMap:");

  System.out.println(identityhashmap);

  System.out.println(identityhashmap.containsKey("3"));//是否包含這個(gè)鍵

  System.out.println(identityhashmap.containsValue("a"));//是否包含值

  Set set=identityhashmap.entrySet();//傳為Set類型

  System.out.println(set);

  set=identityhashmap.keySet();//全部鍵

  System.out.println(set);

  }

  //LinkedHashMap

  {

  LinkedHashMap linkedhashmap=new LinkedHashMap();

  linkedhashmap.put("0","b");

  linkedhashmap.put("2","a");

  linkedhashmap.put("1","c");

  linkedhashmap.put("3","b");

  System.out.println("LinkedHashMap:");

  System.out.println(linkedhashmap);

  System.out.println(linkedhashmap.containsKey("2"));//是否包含這個(gè)鍵

  System.out.println(linkedhashmap.containsValue("c"));//是否包含值

  Set set=linkedhashmap.keySet();

  Iterator iterator=set.iterator();

  while(iterator.hasNext()){

  System.out.print(linkedhashmap.get(iterator.next())+";");

  }

  }

  //LinkedHashSet

  {

  LinkedHashSet linkedhashset=new LinkedHashSet();//它包含了幾種Set的屬性但卻沒有自己的特色

  linkedhashset.add("c");

  linkedhashset.add("a");

  linkedhashset.add("a");

  linkedhashset.add("b");

  System.out.println("\nLinkedHashSet:");

  System.out.println(linkedhashset);

  System.out.println(linkedhashset.contains("a"));//是否包含對象

  Iterator iterator=linkedhashset.iterator();

  while(iterator.hasNext()){

  System.out.print(iterator.next()+";");

  }

  }

  //LinkedList

  {

  LinkedList linkedlist=new LinkedList();//自由使用是它的特色

  linkedlist.add("a");

  linkedlist.add(1,"c");

  linkedlist.addLast("b");

  linkedlist.addFirst("d");

  System.out.println("\nLinkedList:");

  System.out.println(linkedlist);

  //linkedlist.clear();//該方法清空容器

  //linkedlist.remove(0);//刪除索引為0的元素

  //linkedlist.remove("d");//刪除值為d的元素

  //linkedlist.removeFirst();//刪除第一個(gè)元素

  //linkedlist.removeLast();//刪除最后一個(gè)元素

  for(int i=0;i

  System.out.print(linkedlist.get(i)+";");

  }

  }

  //Stack

  {

  Stack stack=new Stack();//堆棧

  stack.add("b");

  stack.add(0,"c");

  stack.push("d");

  stack.add("e");

  stack.push("a");

  Enumeration enumeration=stack.elements();

  System.out.println("\nStack:");

  while(enumeration.hasMoreElements()){

  System.out.print(enumeration.nextElement()+";");

  }

  //后進(jìn)先出

  System.out.println("\n"+stack.peek());

  System.out.println(stack.pop());

  System.out.println(stack.contains("d")+";"+stack.contains("a"));//是否包含該元素,有趣的事情發(fā)生了

  System.out.println(stack.search("c"));//非常有用的屬性,檢索,但是由后向前的排列

  }

  //TreeMap

  {

  TreeMap treemap=new TreeMap();

  treemap.put("0","d");

  treemap.put("2","a");

  treemap.put("1","b");

  treemap.put("3","c");

  System.out.println("\nTreeMap:");//可以對鍵排序

  System.out.println(treemap);

  System.out.println(treemap.firstKey());//返回第一個(gè)鍵

  Set set=treemap.keySet();

  Iterator iterator=set.iterator();

  while(iterator.hasNext()){

  System.out.print(treemap.get(iterator.next())+";");

  }

  }

  //TreeSet

  {

  TreeSet treeset=new TreeSet();//自動(dòng)排序內(nèi)容

  treeset.add("b");

  treeset.add("a");

  treeset.add("c");

  treeset.add("d");

  System.out.println("\nTreeSet:");

  System.out.println(treeset);

  System.out.println(treeset.first());//返回第一個(gè)元素

  Iterator iterator=treeset.iterator();

  while(iterator.hasNext()){

  System.out.print(iterator.next()+";");

  }

  }

  //Vector

  {

  Vector vector=new Vector();

  vector.add(0,"b");

  vector.add("a");

  vector.addElement("d");

  vector.add("c");

  System.out.println("\nVector:");

  System.out.println(vector);

  vector.set(2,"h");//替換掉指定索引的元素

  System.out.println(vector);

  Object []str=vector.toArray();

  for(int i=0;i

  System.out.print(str[i]+";");

  }

  vector.setSize(2);//重新設(shè)置大小為2

  System.out.println("\n"+vector);

  }

  //WeakHashMap

  {

  WeakHashMap weakhashmap=new WeakHashMap();

  weakhashmap.put("1","b");

  weakhashmap.put("2","c");

  weakhashmap.put("0","d");

  weakhashmap.put("3","a");

  System.out.println("\nWeakHashMap:");

  System.out.println(weakhashmap);

  System.out.println(weakhashmap.containsKey("3"));//是否包含鍵

  System.out.println(weakhashmap.containsValue("d"));//是否包含值

  Set set=weakhashmap.entrySet();

  Iterator iterator=set.iterator();

  while(iterator.hasNext()){

  System.out.print(iterator.next()+";");

  }

  //weakhashmap.remove("2");//刪除該鍵對應(yīng)的值

  //weakhashmap.get("1");//獲取指定鍵的值

  }

  }

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