java - java中的扫描器类

Question

嘿，我正在尝试编译以下代码以基本上从文件中读取内容，但它拒绝工作。它在第 4 行给我一个 java.io.FILENOTFOUNDEXCEPTION 错误。帮助将不胜感激。

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


 public class test{
    public static void main(String args[]) {
    File fin = new File ("matrix1.txt");
    Scanner scanner = new Scanner(fin);
       while (scanner.hasNextLine()){
       String line = scanner.nextLine();
       System.out.println(line);
       }
    }
 }

Answer 1

尝试把文件的绝对路径，比如

c:\\java\\matrix1.txt 或 /home/user/java/matrix1.txt

===糟糕

您需要捕获抛出的异常。这里有几个选项:

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

public class test{
    public static void main(String args[]) throws FileNotFoundException {
    File fin = new File ("matrix1.txt");
    Scanner scanner = new Scanner(fin);
       while (scanner.hasNextLine()){
       String line = scanner.nextLine();
       System.out.println(line);
       }
    }
 }

或

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


 public class test{
    public static void main(String args[]) {
       File fin = new File ("matrix1.txt");

       Scanner sc = null;
       try {
           scanner = new Scanner(fin);
       }
       catch(FileNotFoundException e) {
          System.out.println("File does not exist...");
          return;
       }
       while (scanner.hasNextLine()){
       String line = scanner.nextLine();
       System.out.println(line);
       }
    }
 }