Java学习笔记(1)----规则集和线性表性能比较

　　为了比较 HashSet，LinkedHashSet，TreeSet，ArrayList，LinkedList 的性能，使用如下代码来测试它们加入并删除500000个数据的时间：

package src;

import java.util.ArrayList;
import java.util.List;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.LinkedList;
import java.util.TreeSet;

public class Solution {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Collection<Integer>set1=new HashSet<Integer>();
        System.out.println("Time for hash set is "+getTestTime(set1,500000)+" milliseconds");

        Collection<Integer>set2=new LinkedHashSet<Integer>();
        System.out.println("Time for linked hash set is "+getTestTime(set2, 500000)+" milliseconds");

        Collection<Integer>set3=new TreeSet<Integer>();
        System.out.println("Time for tree set is "+getTestTime(set3, 500000)+" milliseconds");

        Collection<Integer>set4=new ArrayList<Integer>();
        System.out.println("Time for arraylist is "+getTestTime(set4, 500000)+" milliseconds");

        Collection<Integer>set5=new LinkedList<Integer>();
        System.out.println("Time for linked list is "+getTestTime(set5, 500000)+" milliseconds");

        System.out.println("\nGame Over!");
    }

    public static long getTestTime(Collection<Integer>c,int size){
        long startTime=System.currentTimeMillis();
        List<Integer>list=new ArrayList<Integer>();
        for(int i=0;i<size;i++){
            list.add(i);
        }

        Collections.shuffle(list);
        for(int ele:list){
            c.add(ele);
        }

        Collections.shuffle(list);

        for(int ele:list){
            c.remove(ele);
        }

        long endTime=System.currentTimeMillis();
        return endTime-startTime;
    }
}

运行结果如下：

Time for hash set is 372 milliseconds
Time for linked hash set is 404 milliseconds
Time for tree set is 936 milliseconds
Time for arraylist is 200759 milliseconds
Time for linked list is 473436 milliseconds

Game Over!

可以看到，速度由快到慢依次是：HashSet，LinkedHashSet，TreeSet，ArrayList，LinkedList。