没有错误检查空列表,但是这里是。
List<List<Integer>> list = Arrays.asList(Arrays.asList(10, 5, 4), Arrays.asList(3, 2, 1), Arrays.asList(7, 8, 6));for (List<Integer> l : list) { Collections.sort(l);}Collections.sort(list, new Comparator<List<Integer>>() { public int compare(List<Integer> o1, List<Integer> o2) { return o1.get(0).compareTo(o2.get(0)); }});System.out.println(list);使用Java 8,它变得更加简洁:
List<List<Integer>> list = Arrays.asList(Arrays.asList(10, 5, 4), Arrays.asList(3, 2, 1), Arrays.asList(7, 8, 6));list.forEach(Collections::sort);Collections.sort(list, (l1, l2) -> l1.get(0).compareTo(l2.get(0)));System.out.println(list);



