隨筆檔案(496)

//ArrayList
{
ArrayList arraylist=new ArrayList();
arraylist.add(0,"end");//指定索引加入值
//需注意的是，如果現有2個值，我加入索引為5的那么就會出現異常
for(int i=0;i<2;i++){
arraylist.add(i,String.valueOf(i));
}
System.out.println("ArrayList:");
for(int i=0;i<arraylist.size();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<list.size();i++){
System.out.print(list.get(i)+";");
}
System.out.print("\nArrays\'s length is "+array.length);//打印數組的長度
}
//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<list.size();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的數據進list
System.out.println("\n"+list);
Collections.swap(list,2,1);//調換索引為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);//一個準容器類型，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();//一個絕對不能重復的類型
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();//刪除第一個元素
//linkedlist.removeLast();//刪除最后一個元素
for(int i=0;i<linkedlist.size();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();//自動排序內容
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<str.length;i++){
System.out.print(str[i]+";");
}
vector.setSize(2);//重新設置大小為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");//刪除該鍵對應的值
//weakhashmap.get("1");//獲取指定鍵的值
}
}