java8 將List 轉List

#將List<Integer> 轉為List<String>

        List<Integer> strings1 = Arrays.asList(69, 1, 365, 2, 655, 3, 3, 4, 4);
        List<String> countList = Optional.of(strings1).orElseGet(ArrayList::new).stream().map(String::valueOf).collect(Collectors.toList());
        //測試結果result: [1, 2, 3, 4, 4]

        //System.out.println("llll" + countList);
        List<String> result = Optional.of(strings1).orElseGet(ArrayList::new).stream().map(x -> x + "").collect(Collectors.toList());
        //測試結果result: [1, 2, 3, 4, 4]

        List<String> strings = Optional.of(strings1).orElseGet(ArrayList::new).stream().distinct().sorted().map(x -> x + "").collect(Collectors.toList());
        //測試結果result: 1, 2, 3, 4, 69, 365, 655]
        System.out.println("llll33333" + strings);