1. First of all, the List
① Collection (the collection framework appeared in JDK1.2 version)
② list: It is ordered, and the elements can be repeated, so the collection system has an index.
Often used are the ArrayList and LinkedList classes that implement this interface
③ Arraylist: The underlying data structure uses an array structure,
Features: Query speed is very fast , but additions and deletions are slightly slower. Threads are not synchronized
LinkedList: The bottom layer uses a linked list data structure.
Features: The addition and deletion speed is very fast, and the query is slightly slower.
Vector: (Appeared in JDK1.0 version) The bottom layer is an array data structure and thread synchronization. Replaced by ArrayList. (No longer used)
2. Two traversal methods for List:
public class Demo { public static void main(String[] args) { ArrayList<String> list = new ArrayList<String>(); list.add("A"); list.add("B"); list.add("C"); System.out.println("........第一种遍历方式:for遍历......"); for (Object li : list) { System.out.println(li); } System.out.println("........第二种遍历方式:ListIterator迭代遍历......"); ListIterator<String> it = list.listIterator(); while (it.hasNext()) { Object obj = it.next(); System.out.println(obj); } } }
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3. Use LinkList to simulate a stack or queue data structure. That is: Stack: first in, last out; Queue: first in, first out
class Duilie{ private LinkedList<Object> link; Duilie(){ link = new LinkedList<Object>(); } public void myAdd(Object obj){ link.addFirst(obj); } public Object myGet(){ return link.removeLast();//先进先出---若要改成先进后出,将removelast()改成removeFirst() } public boolean isNull(){ return link.isEmpty(); } } public class Demo2 { public static void main(String[] args) { Duilie dl = new Duilie(); dl.myAdd("java01"); dl.myAdd("java02"); dl.myAdd("java03"); dl.myAdd("java04"); while(!dl.isNull()){ System.out.println(dl.myGet()); } } }
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The above is first in, first out. If you want to change it to first in, last out, just change it according to what is written in the code.
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