Java中什麼集合查詢最快
阿新 • • 發佈:2019-02-03
上一篇文章中,我們瞭解了ArrayList的的遍歷速度比LinkedList快7000多倍。下面我們看一下什麼結合中查詢物件最快。呵呵程式碼如下:
- package dbtransfer;
- import java.util.ArrayList;
- import java.util.LinkedList;
- import java.util.Random;
- import java.util.HashMap;
- import java.util.HashSet;
- publicclass ListTest {
- privatestatic Random random = new Random();
- publicstaticvoid main(String[] args){
- ArrayList<String> arraylist = new ArrayList();
- LinkedList<String> linkedlist = new LinkedList();
- HashMap<String,Object> map = new HashMap();
- HashSet<String> set = new HashSet();
- for(int i=0;i<50000;i++){
- String r = randomString();
- arraylist.add(r);
- linkedlist.add(r);
- map.put(r, r);
- set.add(r);
- }
- System.out.println("arraylist size "+arraylist.size());
- System.out.println("linkedlist size "+linkedlist.size());
- System.out.println("map size "+map.size());
- System.out.println("set size "+set.size());
- System.out.println("------");
- long
- for(int j=0;j<arraylist.size();j++){
- arraylist.contains(arraylist.get(j));
- }
- System.out.println("arraylist time "+(System.currentTimeMillis()-begin));
- begin = System.currentTimeMillis();
- for(int j=0;j<arraylist.size();j++){
- linkedlist.contains(arraylist.get(j));
- }
- System.out.println("linkedlist time "+(System.currentTimeMillis()-begin));
- begin = System.currentTimeMillis();
- for(int i=0;i<100;i++){
- for(int j=0;j<arraylist.size();j++){
- map.containsKey(arraylist.get(j));
- }
- }
- System.out.println("map time "+(System.currentTimeMillis()-begin));
- begin = System.currentTimeMillis();
- for(int i=0;i<100;i++){
- for(int j=0;j<arraylist.size();j++){
- set.contains(arraylist.get(j));
- }
- }
- System.out.println("set time "+(System.currentTimeMillis()-begin));
- }
- protectedstatic String randomString() {
- return Long.toString(random.nextLong(), 36);
- }
- }