Java 8 流 API /a如何查找按排序順序以小寫字母開頭的前三個字符串。如何使用 打印結果System.out.println()。List<String> myList = Arrays.asList("A1", "a2", "b1", "c2", "A2", "a3", "c2", "A3", "c2", "a1", "a4", "a6"); myList.stream().filter(s -> s.startsWith("a")) .map(String::toLowerCase) .sorted() .forEach(s ->System.out.println("Filtered value: " + s)); a如何只打印按排序順序以小寫字母開頭的前三個字符串？請幫忙& 在這種情況下：我不明白嵌套的這個任務：如何只打印前三個字符串，它們按排序順序以小寫 a 開頭？公共課任務{public static void main(String[] args){final List<String> myList1 = Arrays.asList("c1", "b2", "G3", "g4", "b1", "b3", "G5", "g3", "b5", "e2", "b8", "b2", "g8", "i9", "b10", "j6", "s2", "g2", "B9", "B1", "g7", "b8", "N7", "e9");final List<String> myList2 = Arrays.asList("c1", "b2", "G3", "g4", "b1", "b3", "G5", "g3", "b5", "e2", "b8", "b2", "g8", "i9", "b10", "j6", "s2", "g2", "B9", "B1", "g7", "b8", "N7", "e9");List<List<String>> nestedList = new ArrayList<>();nestedList.add(myList1);nestedList.add(myList2);}}
3 回答
Cats萌萌
TA貢獻1805條經驗 獲得超9個贊
這似乎有效 - 需要告訴列表您正在使用什么類型的對象
List<String> myList = Arrays.asList("A1", "a2", "b1", "c2", "A2",
"a3", "c2", "A3", "c2", "a1", "a4", "a6");
myList.stream().filter(s -> s.startsWith("a")).sorted().limit(3)
forEach(s ->System.out.println("Filtered value: " + s));
此外，由于您只需要小寫，a因此無需轉換為小寫。
jeck貓
TA貢獻1909條經驗 獲得超7個贊
您可以.limit(3)在排序后添加到您的流中。需要輸入列表才能使用 String 方法，除非您希望將結果轉換為小寫，否則List<String>不需要。toLowerCase
List<String> myList = List.of(
"A1", "a2", "b1", "c2", "A2", "a3", "c2", "A3", "c2", "a1", "a4", "a6");
myList.stream().filter(s -> s.charAt(0) == 'a').sorted().limit(3)
.forEach(s -> System.out.println("Filtered value: " + s));
更新：對于從每個字符串的索引 1 開始的數字排序：
Comparator<String> comparator = Comparator.comparing(
s -> Integer.parseInt(s.substring(1)));
myList.stream().filter(s -> s.charAt(0) == 'a').sorted(comparator).limit(3)
.forEach(s -> System.out.println("Filtered value: " + s));
largeQ
TA貢獻2039條經驗 獲得超8個贊
請找到以下相同的代碼：
List<String> myList = Arrays.asList("A1", "a2", "b1", "c2", "A2", "a3", "c2", "A3", "c2", "a1", "a4", "a6");
myList.stream().filter(x-> x.startsWith("a")).sorted().limit(3).forEach(System.out :: println);添加回答
舉報
0/150
提交
取消