# for i 循环 for (int i = 0; i < list.size(); i++) {list.get(i); }# 增强for循环 for (int item : list) { }# iterator for 循环 for (Iterator<Integer> iterator = list.iterator(); iterator.hasNext(); ) {iterator.next(); }# iterator while 循环 Iterator<Integer> iterator = list.iterator(); while (iterator.hasNext()) {iterator.next(); }# list.forEach 循环 list.forEach(item -> { });# list.stream().forEach 循环 list.stream().forEach(item -> { });# list.parallelStream().forEach 循环list.parallelStream().forEach(item -> {}); 性能比较 每种循环各遍历10000_0000次 total cost time : 699 ms for i 循环 : 63 ms, 9.01% iterator for 循环 : 89 ms, 12.73% iterator while 循环 : 86 ms, 12.30% for Boost 循环 : 161 ms, 23.03% list.forEach 循环 : 115 ms, 16.45% list.stream().forEach 循环 : 115 ms, 16.45% list.parallelStream().forEach 循环 : 66 ms, 9.44%