这是我第一次在程序中使用多个方法，我也从未尝试过计算文件中的行、单词和字母。因此，我阅读了三本Java书籍的文件部分，然后查看了论坛上的问题，并进行了尝试。我认为我在变量名方面做得不对，因为我不知道在多方法等中把它们放在哪里的规则。如果你能说这样的事情是明显错误的，因为你必须这样做，那将是有帮助的。我不能使用调试器，因为我不能编译它。无论如何，谢谢你看这个。
import java.util.Scanner;
import java.io.*;
/**
* A program to count the number of lines, words and characters in a text file.
*
* @author
* @version 2014
*/
public class WordCount
{
public static void main(String[] args) throws FileNotFoundException
{
// get the filename
Scanner keyboard = new Scanner(System.in);
System.out.print("Enter the name of the file: ");
String filename = keyboard.nextLine();
File file = new File(filename);
Scanner inputFile = new Scanner(file);
lines(filename);
words(filename);
characters(filename);
}
/**
* Count the number of lines in a file, and print out the result.
*
*/
public static void lines(String filename) throws FileNotFoundException
{
Scanner inputFile = new Scanner(file);
int lines = 0;
while (inputFile.hasNextLine())
{
lines++;
file.nextLine();
}
return lines;
inputFile.close();
}
/**
* Count the number of words in a file, and print out the result.
*
*/
public static void words(String filename) throws FileNotFoundException
{
Scanner inputFile = new Scanner(file);
int words = 0;
while (input.hasNextLine())
{
String word = input.next();
words++;
}
return words;
inputFile.close();
}
/**
* Count the number of characters in a file, and print out the result.
*
*/
public static void characters(String filename) throws FileNotFoundException
{
Scanner inputFile = new Scanner(file);
int characters = 0;
while (inputFile.hasNextLine())
{
String line = inputFile.nextLine();
for(int i = 0; i < line.length(); i++)
{ characters = line.charAt(i);
if (character != 32)
{
characters++;
}
}
}
return characters;
inputFile.close();
System.out.println("The number of lines is: " + lines);
System.out.println("The number of words is: " + words);
System.out.println("The number of characters is: " + characters);
System.out.println();
}
}
更改以下
public static int lines(String filename) throws FileNotFoundException
//change the return type to int instead of void
{
Scanner inputFile = new Scanner(filename); //filename instead of file
int lines = 0;
while (inputFile.hasNextLine())
{
lines++;
inputFile.nextLine(); // ---do----
}
inputFile.close(); // after return it will become unreachable
return lines;
}
同样适用于其他方法
您的代码包含几个问题。因此，让我们在每种方法中逐一解决这个问题：
public static void main(String[] args) throws FileNotFoundException
{
// get the filename
Scanner keyboard = new Scanner(System.in);
System.out.print("Enter the name of the file: ");
String filename = keyboard.nextLine();
keyboard.close(); // <- don't forget to close this resource
File file = new File(filename);
//Scanner inputFile = new Scanner(file); // <- this line is unnecessary, because you never use that variable
lines(file); // <- you already obtained a File object, so use it ;)
words(file);
characters(file);
}
下一种方法：
public static void lines(File file) throws FileNotFoundException // mind the new argument type
{
Scanner inputFile = new Scanner(file);
int lines = 0;
while (inputFile.hasNextLine())
{
lines++;
inputFile.nextLine(); //<- use "inputFile" instead of "file"
}
inputFile.close();
//return lines; // <- you can't return something if your method uses "void" as the return type
//your comment on that method says that you like to print the result, so let's do that
System.out.println("The number of lines is: " + lines);
}
下一个：
public static void words(File file) throws FileNotFoundException // <- new argument type
{
Scanner inputFile = new Scanner(file);
int words = 0;
while (inputFile.hasNextLine())
{
//String word = inputFile.next(); // that won't work like you think, but we can do a little "trick" here
String line = inputFile.nextLine(); // read the current line of text
words += line.split(" ").length; // split the line using whitespace and add the number of words to the current value of variable "words"
//words++; // <- not needed anymore
}
//return words; // <- like before: not possible if return type is void
inputFile.close();
//your comment on that method says that you like to print the result, so let's do that
System.out.println("The number of words is: " + words);
}
最后一种方法：
public static void characters(File file) throws FileNotFoundException
{
Scanner inputFile = new Scanner(file);
int characters = 0;
int count = 0; // new variable to count the characters
while (inputFile.hasNextLine())
{
String line = inputFile.nextLine();
for(int i = 0; i < line.length(); i++)
{
characters = line.charAt(i); // <- no harm in using a new line :)
if (characters != 32) // <- you wrote "character"
{
count++; // <- "characters" is the current character itself, we won't increase that. For example "a" would become "b" and we don't want/need that :)
}
}
}
//return characters; // <- you know that already ...
inputFile.close();
//System.out.println("The number of lines is: " + lines); // <- "lines" and "words" are unknown here, but we printed these results already
//System.out.println("The number of words is: " + words);
System.out.println("The number of characters is: " + count); // <- print the count of characters
System.out.println();
}
在这些更改之后，您的代码现在应该可以工作了：）。
这些方法似乎只需要File对象。
int n = countLines(file);
System.out.println("Lines: " + n);
...
public static int countLines(File textFile) throws IOException
{
Scanner inputFile = new Scanner(textFile);
int lines = 0
while (inputFile.hasNextLine())
{
lines++;
inputFile.nextLine();
}
inputFile.close();
return lines;
}
对于下一行，您询问了错误的对象，需要扫描仪。
return从方法返回，所以之前已经接近了。
当您返回行计数时，您必须返回内部
方法名称按约定包含一个动词。
该方法不知道file或filename。如果您传递一个变量（如file），您可以为新的参数赋予相同的名称，但为了清晰起见，此处未进行说明。
问题编号1:
public static void lines(String filename) throws FileNotFoundException
{
Scanner inputFile = new Scanner(file);
int lines = 0;
while (inputFile.hasNextLine())
{
lines++;
file.nextLine();
}
return lines; // <----------------
inputFile.close();
}
这是一个void方法，但是您有一个return lines语句。删除它或将方法标头更改为public static int lines(String filename) throws FileNotFoundException
问题2
public static void words(String filename) throws FileNotFoundException
{
Scanner inputFile = new Scanner(file);
int words = 0;
while (input.hasNextLine())
{
String word = input.next();
words++;
}
return words; <-------------
inputFile.close();
}
在这里，您再次请求void方法返回一个值。将方法标题更改为public static int words(String filename) throws FileNotFoundException
问题3：
public static void characters(String filename) throws FileNotFoundException
{
Scanner inputFile = new Scanner(file);
int characters = 0;
while (inputFile.hasNextLine())
{
String line = inputFile.nextLine();
for(int i = 0; i < line.length(); i++)
{ characters = line.charAt(i);
if (character != 32)
{
characters++;
}
}
}
return characters; //<---------------
inputFile.close();
System.out.println("The number of lines is: " + lines);
System.out.println("The number of words is: " + words);
System.out.println("The number of characters is: " + characters);
System.out.println();
}
这里还有一个关于void方法的return int语句。只需将方法标题更改为：public static int characters(String filename) throws FileNotFoundException