Question

我有一个程序，它应该计算指定文件中特定字符的所有实例，例如“A”。我得到它来计算角色，除了它只看一个单词开头的字符。因此，“aa aaa a ba”只算作4“A”而不是7.我尽可能地评论，所以我的思路清晰，但我对编程很新，所以我提前道歉如果我不清楚的话。

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

public class Charcounter
{
public static void main(String[] args) throws IOException
{
    //accumulator
    int sum = 0;

    Scanner kb = new Scanner(System.in);

    //get filename and character to be counted from user
    System.out.println("Enter the name of a file: ");
    String filename = kb.nextLine();
    System.out.println("Enter the name of the character to be counted: ");
    char countedChar = kb.next().charAt(0);

    //check if file exists
    File file = new File(filename);
    if (!file.exists())
    {
        System.out.println("File specified not found.");
        System.exit(0);
    }

    //open file for reading
    Scanner inputFile = new Scanner(file);

    //read file and count number of specified characters
    while (inputFile.hasNext())
    {
        //read a char from the file
        char count = inputFile.next().charAt(0);

        //count the char if it is the one specified
        if (count == countedChar)
        {
             ++sum;
        }

    }

    //close file
    inputFile.close();

    //display number of the specified char
    System.out.println("The number of the character '" + countedChar + "' is : " + sum);
}
}

Answer 1

这是因为你只是在比较第一个角色。

 //read a char from the file
 // THIS : only the first character
 char count = inputFile.next().charAt(0);

 //count the char if it is the one specified
 if (count == countedChar)
 {
   ++sum;
 }

你应该循环遍历所有字符，然后如果它与countedChar相匹配则增加总和，例如..

 String str = inputFile.next()
 for (int i = 0; i < str.length(); i++) {
   char count = str.charAt(i);   
   // check if it matches the countedChar and then increment.
 }

Answer 2

那是因为你只是在读第一个字符

    String word = inputFile.next();     //read a word
    int counter = 0; 

    for(counter=0;counter<word.length();counter++) // traverse through the word
    { 
        char count = word.charAt(i);       // ith char

        //count the char if it is the one specified
        if (count == countedChar)
        {
             ++sum;
        }
   }

Answer 3

尝试使用一个变量而不是零，它在类的开头初始化为零，然后为它计数的每个char递增它，所以：

   //read a char from the file
    char count = inputFile.next().charAt(m);
    ++m;
    //count the char if it is the one specified
    if (count == countedChar)
    {
         ++sum;
    }

然后在main方法中定义：

   int m = 0

Answer 4

这是因为你正在使用

char count = inputFile.next().charAt(0);

默认情况下，next会读取，直到它找到空格或数据结尾，所以现在它会读取并返回整个单词。

如果您想要使此方法有效，则需要next一次只返回一个字符，因此在imputFile扫描程序中设置分隔符以清空inputFile.useDelimiter("");之类的字符串。

Answer 5

while (inputFile.hasNext()) {
    String word = inputFile.next();
    for (int i = 0; i < word.length(); i++) {
        if (word.charAt(i) == countedChar) {
            ++sum;
        }
    }
}

Answer 6

作为替代方案，您可以使用专用于阅读的阅读器：

BufferedReader reader = new BufferedReader(new FileReader(file));

int read;

while((read = reader.read())>0) if (read==countedChar) count++;

reader.close();

在java中计算特定的char，但我的程序只读取单词中的第一个字符

6 个答案: