java的遍历数组效率测试源码

来源：互联网发布：王源父母知乎编辑：程序博客网时间：2024/06/07 14:08

package javatest;import java.util.ArrayList;import java.util.Iterator;import java.util.List;public class javatest {public static void main(String[] args) {List<String> list = new ArrayList<String>();long t1,t2;for(int j = 0; j < 10000000; j++){list.add("aaaaaabbbbbbbcccccccc");}//==================== 方式 1 =========================t1=System.currentTimeMillis();for(String tmp:list){//System.out.println(tmp);}t2=System.currentTimeMillis();System.out.println("List first visit method Run Time:" + (t2 -t1) + "(ms)");//==================== 方式 2 =========================t1=System.currentTimeMillis();for(int i = 0; i < list.size(); i++){list.get(i);//System.out.println(list.get(i));}t2=System.currentTimeMillis();System.out.println("List second visit method Run Time:" + (t2 -t1) + "(ms)");//===================== 方式 3 ========================Iterator<String> iter = list.iterator();t1=System.currentTimeMillis();while(iter.hasNext()){iter.next();//System.out.println(iter.next());}t2=System.currentTimeMillis();System.out.println("List Third visit method Run Time:" + (t2 -t1) + "(ms)");}}

运行结果：

不是每次都是一样的，总体效率是：方式2 > 方式3 > 方式1

0 0