1. 程式人生 > >Java 集合系列08之 List總結(LinkedList, ArrayList等使用場景和效能分析)

Java 集合系列08之 List總結(LinkedList, ArrayList等使用場景和效能分析)

1 import java.util.*; 2 import java.lang.Class; 3 4 /* 5 * @desc 對比ArrayList和LinkedList的插入、隨機讀取效率、刪除的效率 6 * 7 * @author skywang 8 */ 9 public class ListCompareTest { 10 11 private static final int COUNT = 100000; 12 13 private static LinkedList linkedList = new LinkedList(); 14 private
static ArrayList arrayList = new ArrayList(); 15 private static Vector vector = new Vector(); 16 private static Stack stack = new Stack(); 17 18 public static void main(String[] args) { 19 // 換行符 20 System.out.println(); 21 // 插入 22 insertByPosition(stack) ;
23 insertByPosition(vector) ; 24 insertByPosition(linkedList) ; 25 insertByPosition(arrayList) ; 26 27 // 換行符 28 System.out.println(); 29 // 隨機讀取 30 readByPosition(stack); 31 readByPosition(vector); 32 readByPosition(linkedList); 33
readByPosition(arrayList); 34 35 // 換行符 36 System.out.println(); 37 // 刪除 38 deleteByPosition(stack); 39 deleteByPosition(vector); 40 deleteByPosition(linkedList); 41 deleteByPosition(arrayList); 42 } 43 44 // 獲取list的名稱 45 private static String getListName(List list) { 46 if (list instanceof LinkedList) { 47 return "LinkedList"; 48 } else if (list instanceof ArrayList) { 49 return "ArrayList"; 50 } else if (list instanceof Stack) { 51 return "Stack"; 52 } else if (list instanceof Vector) { 53 return "Vector"; 54 } else { 55 return "List"; 56 } 57 } 58 59 // 向list的指定位置插入COUNT個元素,並統計時間 60 private static void insertByPosition(List list) { 61 long startTime = System.currentTimeMillis(); 62 63 // 向list的位置0插入COUNT個數 64 for (int i=0; i<COUNT; i++) 65 list.add(0, i); 66 67 long endTime = System.currentTimeMillis(); 68 long interval = endTime - startTime; 69 System.out.println(getListName(list) + " : insert "+COUNT+" elements into the 1st position use time:" + interval+" ms"); 70 } 71 72 // 從list的指定位置刪除COUNT個元素,並統計時間 73 private static void deleteByPosition(List list) { 74 long startTime = System.currentTimeMillis(); 75 76 // 刪除list第一個位置元素 77 for (int i=0; i<COUNT; i++) 78 list.remove(0); 79 80 long endTime = System.currentTimeMillis(); 81 long interval = endTime - startTime; 82 System.out.println(getListName(list) + " : delete "+COUNT+" elements from the 1st position use time:" + interval+" ms"); 83 } 84 85 // 根據position,不斷從list中讀取元素,並統計時間 86 private static void readByPosition(List list) { 87 long startTime = System.currentTimeMillis(); 88 89 // 讀取list元素 90 for (int i=0; i<COUNT; i++) 91 list.get(i); 92 93 long endTime = System.currentTimeMillis(); 94 long interval = endTime - startTime; 95 System.out.println(getListName(list) + " : read "+COUNT+" elements by position use time:" + interval+" ms"); 96 } 97 }