java文件I/O和异常

Question

我试图编写一个程序，提示用户输入文件名，读取应该包含两列浮点数的文件，最后打印每列的平均值。使用try/catch/finally块

Scanner in = new Scanner(System.in);
        System.out.println("Please enter the file name: ");
        String file = in.nextLine();
        try{
            Scanner inFile = new Scanner(new File(file));
            int count = 0;
            float average1 = 0;
            float average2 = 0;
            while (inFile.hasNextFloat()) {
                String str = inFile.nextLine();
                Scanner line = new Scanner(str);
                line.useDelimiter(" ");
                average1 = Float.parseFloat(line.next());
                average2 = Float.parseFloat(line.next());
                average1 += in.nextFloat();
                average2 += in.nextFloat();
            }
            System.out.println("The average of the first column: " + average1 / count);
            System.out.println("The average of the second column: " + average2 / count);
        }
        catch (FileNotFoundException e) {
            System.out.println("File not found.");
        }
    }

由于某些原因，它仍在运行，无法找出原因和解决方法。 是的，它读取文件，但不提供输出并继续运行。 谁能帮助确定问题并帮助我解决它

Answer 1

代码没有结束的原因是in.nextFloat()只是坐在那里等待来自命令行的输入。您不需要这一行，因为您已经分析了前一行中的输入。您可以简单地将其添加到平均值中，而不是将其赋值（否则只会在每次迭代中替换平均值）。一旦解决了这个问题，还需要增加计数。下面是一个工作示例：

Scanner in = new Scanner(System.in);
        System.out.println("Please enter the file name: ");
        String file = in.nextLine();
        try{
            Scanner inFile = new Scanner(new File(file));
            int count = 0;
            float average1 = 0;
            float average2 = 0;
            while (inFile.hasNextFloat()) {
                String str = inFile.nextLine();
                Scanner line = new Scanner(str);
                line.useDelimiter(" ");
                average1 += Float.parseFloat(line.next());
                average2 += Float.parseFloat(line.next());
                count++;
            }
            System.out.println("The average of the first column: " + average1 / count);
            System.out.println("The average of the second column: " + average2 / count);
        }
        catch (FileNotFoundException e) {
            System.out.println("File not found.");
        }