java我正在尝试从文件中计算字符数

Question

我在这里要做的是读取一个文件并计算每个字符。每个字符应在“int count”上加+1，然后打印出“int count”的值

我希望我要做的是清楚的

import java.io.*;
import java.util.Scanner;

public class ScanXan {

public static void main(String[] args) throws IOException {

    int count = 0;
    Scanner scan = null;
    Scanner cCount = null;

    try {
        scan = new Scanner(new BufferedReader(new FileReader("greeting")));

        while (scan.hasNextLine()) {
            System.out.println(scan.nextLine());
        }
    }

    finally {
        if (scan != null) {
            scan.close();
        }
    }

    try {

        cCount = new Scanner(new BufferedReader(new  FileReader("greeting")));
        while (cCount.hasNext("")) {
            count++;
        }
    }

    finally {
        if (cCount != null) {
            scan.close();
        }
    }

    System.out.println(count);

}

}

Answer 1

1. 添加catch块以检查异常
2. 从hasNext（“”）中删除参数

3. 移动到下一个令牌

       cCount = new Scanner(new BufferedReader(new  FileReader("greeting")));
       while (cCount.hasNext()) {
               count = count + (cCount.next()).length();
       }
   

Answer 2

首先，为什么要使用try { }而不使用catch(Exception e)

BufferedReader reader = null;
try {
reader = new BufferedReader(new    FileReader("greetings.txt"));
String line = null;
String text = "";
while ((line = reader.readLine()) != null) {
     text += line;
}
int c = 0; //count of any character except whitespaces
 // or you can use what @Alex wrote
 // c = text.replaceAll("\\s+", "").length();    
for (int i = 0; i < text.length(); i++) {
    if (!Character.isWhitespace(text.charAt(i))) {
        c++;
    }
}
System.out.println("Number of characters: " +c);
} catch (IOException e) {
     System.out.println("File Not Found");
} finally {
     if (reader != null) { reader.close();
     }
}

Answer 3

如果你在寻找一种只计算所有字符和整数的方法，而不需要任何空格，比如“tab”、“enter”等等。。然后，您可以首先使用以下函数删除这些空白：

st.replaceAll("\\s+","")

然后你只需要做一个字符串计数

String str = "a string";
int length = str.length( );

Answer 4

使用Java8流API，您可以按如下方式进行

package example;

import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.stream.Collectors;
import java.util.stream.Stream;

public class CountCharacter {

    private static int count=0;

    public static void main(String[] args) throws IOException {
        Path path = Paths.get("greeting");
        try (Stream<String> lines = Files.lines(path, StandardCharsets.UTF_8)) {
            count = lines.collect(Collectors.summingInt(String::length));
        }
        System.out.println("The number of charachters is "+count);
    }

}