public class MyDemo {    private static final Logger log = LoggerFactory.getLogger(MyDemo.class);    public static void main(String[] args) {        List
     
       list = new ArrayList();        for(int i =0;i<1000000;i++){            list.add(i);        }        long end = System.currentTimeMillis();        for(Integer i:list){            new String();        }        long start = System.currentTimeMillis();        log.info("for :::::>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>总耗时："+(start-end));        for(int i=0;i
      
       >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>总耗时："+(end-start));        list.stream().map(s->{            return  new String();        });        start = System.currentTimeMillis();        log.info("stream()>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>总耗时："+(start-end));        list.forEach(s->{                    new String();                }        );        end = System.currentTimeMillis();        log.info("foreach  >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>总耗时："+(end-start));    }}
      
     

结果输出：

[INFO] for :::::>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>总耗时：7[INFO] for size  >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>总耗时：5[INFO] stream()>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>总耗时：48[INFO] foreach  >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>总耗时：7

综合结果：for size>for>foreach>stream()