java list三种遍历方法性能比较

public static void compare() {    List<String> list = new ArrayList<String>();    Set<String> set = new HashSet<String>();    for(int i=0;i<100000;i++) {        list.add("a"+i);    }    long t1=0L,t2=0L;    t1 = System.currentTimeMillis();    for(String s : list) {        set.add(s);    }    t2 = System.currentTimeMillis();    System.out.println("forEach遍历的时间为："+(t2-t1)+"mm");    ////two    t1 = System.currentTimeMillis();    for(int i=0; i<list.size(); i++) {        String str = list.get(i);        set.add(list.get(i));    }    t2 = System.currentTimeMillis();    System.out.println("size遍历的时间为："+(t2-t1)+"mm");    ////three    t1 = System.currentTimeMillis();    Iterator<String> iterator = list.iterator();    while(iterator.hasNext()) {        String str = iterator.next();        set.add((String)iterator.next());    }    t2 = System.currentTimeMillis();    System.out.println("iterator遍历的时间为："+(t2-t1)+"mm");}

forEach遍历的时间为：45mmsize遍历的时间为：14mmiterator遍历的时间为：7mm