主页 / 问题 / 813721
Accepted
Oleg Khegay
Asked:2020-04-13 18:09:28 +0000 UTC2020-04-13 18:09:28 +0000 UTC

如何计算文本文件中大写和小写字母的数量？

  • 772

我知道如何从字符串中做到这一点。用计数器很简单。

for (int k = 0; k < input.length(); k++) {
    if (Character.isUpperCase(input.charAt(k))) upperCase++;
    if (Character.isLowerCase(input.charAt(k))) lowerCase++;
}    
System.out.printf("Всего %d заглавных букв и %d прописных.",upperCase,lowerCase);

但是如何将它应用到文件中呢？通过 FileInputStream 上传文件后，如何从头到尾循环并应用它？对不起“菜鸟”的问题。

java

4 个回答

  1. 没有什么能阻止您利用您的知识稍微更改代码：

        import java.io.ByteArrayInputStream;
    import java.io.InputStream;
    import java.util.Scanner;

    public class FileTest {
        public static void main(String[] args) {
            String file = "Например это текст из файла\nахахахаха";
            count(new ByteArrayInputStream(file.getBytes()));

            //ВАШ вариант с файлом
    //        try {
    //            count(new FileInputStream(new File("ВАШ ФАЙЛ")));
    //        } catch (FileNotFoundException e) {
    //            e.printStackTrace();
    //        }
        }

        private static void count(InputStream inputStream) {
            int upperCase = 0;
            int lowerCase = 0;

            try (Scanner scanner = new Scanner(inputStream, "UTF-8");) {
                while (scanner.hasNextLine()) {
                    String line = scanner.nextLine();
                    for (int k = 0; k < line.length(); k++) {
                        if (Character.isUpperCase(line.charAt(k))) upperCase++;
                        if (Character.isLowerCase(line.charAt(k))) lowerCase++;
                    }
                }
            }
            System.out.printf("Всего %d заглавных букв и %d прописных.\n", upperCase, lowerCase);
        }
    }
    • 3
  2. Best Answer

    使用例如BufferedReader

    FileReader fr = new FileReader("file.txt");
BufferedReader br = new BufferedReader(fr);
String s;
while((s = br.readLine()) != null){
    //ваш уже готовый подсчет для одной строки
}
br.close();

    或者更多，但更漂亮：

    FileReader fr = new FileReader("file.txt");
BufferedReader br = new BufferedReader(fr);
br.lines()
    .map(Letters::stringToLettersCount)
    .reduce(Letters::sum)
    .ifPresent(l -> System.out.println(l.toString()));
br.close();

    public class Letters {
    private int lower;
    private int upper;
    public void incLower(){
        lower++;
    }
    public void incUpper(){
        upper++;
    }
    public int getLower() {
        return lower;
    }
    public int getUpper() {
        return upper;
    }
    public Letters add(Letters letters){
        this.upper += letters.getUpper();
        this.lower += letters.getLower();
        return this;
    }
    public static Letters sum(Letters l1, Letters l2){
        Letters l = new Letters();
        l.add(l1);
        l.add(l2);
        return l;
    }
    public static Letters stringToLettersCount(String s){
        Letters l = new Letters();
        for (char c : s.toCharArray()) {
            if (Character.isUpperCase(c)) l.incUpper();
            else if (Character.isLowerCase(c)) l.incLower();
        }
        return l;
    }

    @Override
    public String toString() {
        return "UpperCase: " + upper + ", LowerCase: " + lower; 
    }
}
    • 3

  3. 使用最少的代码并且没有包装器。只有从文件中读取文本行的逻辑已添加到您的代码中。

    int lower = 0, upper = 0;

try {
    for (String line : Files.readAllLines(Path path = Paths.get("file.txt");)) {
        for (int k = 0; k < line.length(); k++) {
            if (Character.isUpperCase(line.charAt(k))) {
                upper++;
            } else {
                lower++;
            }
        }
    }
} catch (IOException e) {
    e.printStackTrace();
}

System.out.println("Lower: " + lower + ", upper: " + upper);
    • 2 
  4. Map<Boolean, Long> map = Files.lines(Paths.get("file.txt"))
                              .map(String::chars)
                              .flatMap(is -> is.mapToObj(c -> (char) c))
                              .collect(
                                Collectors.groupingBy(
                                  Character::isUpperCase,
                                  Collectors.counting()));

System.out.printf("Всего %d заглавных букв и %d прописных.",
                  map.getOrDefault(true, 0),
                  map.getOrDefault(false, 0));
    • 0

相关问题