为什么我在文件 input/output 的 java 程序中出现此错误？

Question

我无法理解为什么会出现这种类型的错误。

这个话题我不是很懂。我这样做是因为这是我在大学的实际提交。

输出中显示的错误：

>PS E:\Vedang\Java_Package> cd "e:\Vedang\Java_Package\" ; if ($?) { javac FileRandomIntegers.java } ; if ($?) { java FileRandomIntegers }

>FileRandomIntegers.java:9: error: constructor File in class File cannot be applied to given types;
          File inFile = new File("rand.dat");  
                        ^
 > required: no arguments
 > found:    String
 > reason: actual and formal argument lists differ in length

>FileRandomIntegers.java:13: error: no suitable constructor found for FileWriter(File)
               FW = new FileWriter(inFile);
                    ^
 >    constructor FileWriter.FileWriter(String) is not applicable
      (argument mismatch; File cannot be converted to String)
 >    constructor FileWriter.FileWriter(java.io.File) is not applicable
      (argument mismatch; File cannot be converted to java.io.File)
 >    constructor FileWriter.FileWriter(FileDescriptor) is not applicable
      (argument mismatch; File cannot be converted to FileDescriptor)

>FileRandomIntegers.java:39: error: no suitable constructor found for Scanner(File)
               Scanner scanner = new Scanner(inFile);
                                 ^
>     constructor Scanner.Scanner(Readable) is not applicable
      (argument mismatch; File cannot be converted to Readable)
>     constructor Scanner.Scanner(InputStream) is not applicable
      (argument mismatch; File cannot be converted to InputStream)
>     constructor Scanner.Scanner(java.io.File) is not applicable
      (argument mismatch; File cannot be converted to java.io.File)
>     constructor Scanner.Scanner(Path) is not applicable
      (argument mismatch; File cannot be converted to Path)
> >    constructor Scanner.Scanner(String) is not applicable
      (argument mismatch; File cannot be converted to String)
> >    constructor Scanner.Scanner(ReadableByteChannel) is not applicable
      (argument mismatch; File cannot be converted to ReadableByteChannel)

>Note: Some messages have been simplified; recompile with -Xdiags:verbose to get full output
3 errors

代码：

    import java.io.*;  
             import java.util.*;  
             class FileRandomIntegers  
             {  
                  public static void main(String args[])  
                  {  
                       FileWriter FW = null;  
                       BufferedWriter bfwr = null;  
                       File inFile = new File("rand.dat");  
                       try  
                       {  
                            int rand_int;  
                            FW = new FileWriter(inFile);  
                            bfwr = new BufferedWriter(FW);  
                            Random generate_rand = new Random();  
                            System.out.println("\nGenerating & Storing Random integers from 0 to 99..\n");  
                            for(int i=0; i<10; i++)  
                            {  
                                 rand_int = generate_rand.nextInt(100);  
                                 System.out.print(rand_int+"\t");  
                                 bfwr.write(rand_int+"\r\n");  
                            }  
                       }  
                       catch(IOException e)  
                       {  
                            System.out.println(e.getMessage());  
                       }  
                       finally  
                       {  
                            try  
                            {  
                                 bfwr.close();  
                            }  
                            catch(IOException e){ }  
                       }  
                       try  
                       {  
                            System.out.println("\nRetrieving Random integers stored in file 'rand.dat'..");  
                            Scanner scanner = new Scanner(inFile);  
                            while(scanner.hasNextInt())  
                            {  
                                 System.out.println(scanner.nextInt()+"\t");  
                            }  
                       }  
                       catch(NullPointerException e)  
                       {  
                            System.out.println(e.getMessage());  
                       }  
                       catch(FileNotFoundException e)  
                       {  
                            System.out.println(e.getMessage());  
                       }            
                  }  
             }

Answer 1

这是我的一项测试的结果。

Generating & Storing 10 Random integers from 0 to 99.
86 33 63 1 36 97 20 82 25 9 

Retrieving Random integers stored in file random.dat
86 33 63 1 36 97 20 82 25 9 

我把你的代码分解成我可以单独测试的更简单的方法。

我也用了 BufferedReader 来读取文件，因为你用了 BufferedWriter 来写入文件。

这是我使用的完整可运行代码。

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Random;

public class FileRandomIntegers {

    public static void main(String[] args) {
        new FileRandomIntegers().createAndProcessFile();
    }
    
    private Random random;
    
    public void createAndProcessFile() {
        this.random = new Random();
        File file = new File("random.dat");
        try {
            writeFile(file);
            readFile(file);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    
    public void writeFile(File file) throws IOException {
        BufferedWriter writer = new BufferedWriter(new FileWriter(file));
        System.out.println("Generating & Storing 10 Random integers "
                + "from 0 to 99.");
        for (int index = 0; index < 10; index++) {
            int number = random.nextInt(100);
            System.out.print(number + " ");
            writer.write(Integer.toString(number));
            writer.write(System.lineSeparator());
        }
        System.out.println();
        System.out.println();
        writer.flush();
        writer.close();
    }
    
    public void readFile(File file) throws IOException {
        BufferedReader reader = new BufferedReader(new FileReader(file));
         System.out.println("Retrieving Random integers stored in file " + 
                 file.getName());  
        String line = reader.readLine();
        while (line != null) {
            System.out.print(line + " ");
            line = reader.readLine();
        }
        System.out.println();
        System.out.println();
        reader.close();
    }

}