Java文件未被正确读取

-2

这是一个修复后表达式计算器和使用文件输入进行操作的文件读取器。当按下F并输入文件名时，程序将假设对文件的内容进行操作，并在输出有效时输出，但是它会一直跳到catch并抛出错误。我不明白为什么，有什么建议？Java文件未被正确读取

import java.io.File; 
import java.util.Scanner; 
import java.io.FileNotFoundException; 
public class assignment { 

    public static void main(String[] args) { 
     String option; 
     char letter; 
    while(true) 
    { 
     Scanner scanner = new Scanner(System.in); 
     System.out.println("Enter K to input data or F to use file input"); 
     option = scanner.nextLine(); 
     letter = option.charAt(0); 

     switch (Character.toUpperCase(letter)) 
     { 
     case 'K': 
     System.out.println("Please enter a calculation, or press enter to close"); 

     String line = scanner.nextLine(); 

      if (line.equals("")) 
      { 
       System.out.println("Calculator has been closed"); 
       System.exit(0); 
      } 

     String [] element = line.split(" "); 

      if (element.length == 3) 
      { 
      System.out.println("You enter: " + element[0]+ " " + element[1]+" " + element[2]); 
      try{ 
       double number1, number2; 
       number1 = Double.parseDouble(element[0]); 
       number2 = Double.parseDouble(element[1]); 

        if (element[2].equals("+")) 
        { 
         System.out.println("Total:" + (number1 + number2)); 
        } 
        else if (element[2].equals("/")) 
        { 
         System.out.println("Total:" + (number1/number2)); 
        } 
        else if (element[2].equals("-")) 
        { 
         System.out.println("Total:" + (number1 - number2)); 
        } 
        else if (element[2].equals("*")) 
        { 
         System.out.println("Total:" + (number1 * number2)); 
        } 
        else{ 
        System.out.println("That is incorect input; please try again"); 
        scanner.close(); 
        } 
       } 
      catch(NumberFormatException e) 
       { 
       System.out.println("Error"+e.getMessage()); 
       } 
     } 
      else{ 
       System.out.println("You have inserted Incorrect input"); 
      } 

     break; 
     case 'F': 
      try{ 
      System.out.println("you have chosen to use a file input"); 
      Scanner file = new Scanner (System.in); 
      System.out.println("input file name:"); 
      String input = file.nextLine(); 
      Scanner s = new Scanner (new File (input)); 


       while (s.hasNext()) { 

      line = s.nextLine(); 
      String FileInput [] =input.split(" "); 

       try 
       { 
        double inp1, inp2; 
        inp1 = Double.parseDouble(FileInput[0]); 
        inp2 = Double.parseDouble(FileInput[1]); 

        if (FileInput[2].equals("+")) 
        { 
         System.out.println("Total:" + (inp1 + inp2)); 
        } 
        else if (FileInput[2].equals("/")) 
        { 
         System.out.println("Total:" + (inp1/inp2)); 
        } 
        else if (FileInput[2].equals("-")) 
        { 
         System.out.println("Total:" + (inp1 - inp2)); 
        } 
        else if (FileInput[2].equals("*")) 
        { 
         System.out.println("Total:" + (inp1 * inp2)); 
        } 
        else 
        { 
        System.out.println("That is incorect input; please try again"); 
        } 
       } 
       catch(NumberFormatException e) 
       { 
        System.out.println("invalid number" + e); 
       } 
      } 
      System.out.println("\nEOF"); 
      file.close(); 
      s.close(); 
      break; 
      } 
      catch (FileNotFoundException e) { 
       System.out.println("incorrect filename"); 
      } 
      default: 
    System.out.println("Incorrect letter entered"); 
    }   
} 
} 
}

来源

2015-11-05 Eaven Strong

最新错误？我看到numberformat异常或filenotfound异常。哪一个？也可以尝试将's.hasNext（）'改为's.hasNextLine（）' – 3kings

并且它“抛出”的错误是......？（总是报告抛出的实际异常。）如果重新格式化了代码，它也会有所帮助... –

还要注意，您提供的大部分代码似乎与问题无关。我的猜测是这个问题实际上是你在System.in上创建了多个扫描器，但目前很难说清楚。 –

您应该只创建一次Scanner实例。
广场 Scanner scanner = new Scanner(System.in); 如在第一条语句的主（循环之前），并删除其他new Scanner
的原因是每个扫描仪缓冲。

来源

2015-11-05 15:35:10 krzydyn

Java文件未被正确读取

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