Detailed explanation of List collection and its traversal in Java-javaTutorial-php.cn

1. First of all, the List collection inherits from Collection , which is an interface.

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 list = new ArrayList(); 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 it = list.listIterator(); while (it.hasNext()) { Object obj = it.next(); System.out.println(obj); } } }

Copy after login

Rendering:

Detailed explanation of List collection and its traversal in Java