Question

我创建了三个文本文件，inputt.txt，outputt.txt和＆amp; errorr.txt。 Inputt.txt用于输入，outputt.txt应该打印inputt.txt中有效整数的所有数字，errorr.txt打印输入文本文件中的所有错误。我在迭代方面遇到了麻烦。 System.out.println打印出inputt.txt中的所有数字就好了;但是，当我尝试将所有数字打印到outputt.txt时，它只打印第一行数字。这是我的代码：

import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintStream;
import java.io.PrintWriter;
import java.util.InputMismatchException;
import java.util.NoSuchElementException;
import java.util.Scanner;

public class Lab5_Exceptions_Redo extends Exception {

    public static void main(String[] args) throws FileNotFoundException {

        String file = "inputt.txt";
        String file1 = "outputt.txt";
        String file2 = "errorr.txt";

        PrintWriter errorr = new PrintWriter(file2);
        PrintStream ps = new PrintStream(file2);

        PrintWriter outputt = new PrintWriter(file1);
        Scanner scan = new Scanner(new File(file));
        while (scan.hasNext()) {
            try {

                String number = scan.nextLine();
                int num = Integer.parseInt(number);
                System.out.println(num);
                outputt.println(num);
            } catch (InputMismatchException e) {
                errorr.println("There was an input mismatch error.");
                errorr.println(e.getMessage());
                e.printStackTrace(ps);
            } catch (NoSuchElementException e) {
                errorr.println("There is no such element.");
                errorr.println(e.getMessage());
                e.printStackTrace(ps);
            } catch (UnsupportedOperationException e) {
                errorr.println("An unsupported operation occured.");
                errorr.println(e.getMessage());
                e.printStackTrace(ps);
            } catch (NumberFormatException e) {
                errorr.println("Number Format Exception.");
                errorr.println(e.getMessage());
                e.printStackTrace(ps);
            }

            errorr.close();
            outputt.close();
        }
        scan.close();
    }
}

Answer 1

PrintWriter流变量errorr应该移出for循环。请尝试以下版本的代码。

public class Lab5_Exceptions_Redo extends Exception {

public static void main(String[] args) throws FileNotFoundException {

    String file = "inputt.txt";
    String file1 = "outputt.txt";
    String file2 = "errorr.txt";

    PrintWriter errorr = new PrintWriter(file2);
    PrintStream ps = new PrintStream(file2);

    PrintWriter outputt = new PrintWriter(file1);
    Scanner scan = new Scanner(new File(file));
    while (scan.hasNext()) {
        try {
            String number = scan.nextLine();
            int num = Integer.parseInt(number);
            System.out.println(num);
            outputt.println(num);
        } catch (InputMismatchException e) {
            errorr.println("There was an input mismatch error.");
            errorr.println(e.getMessage());
            e.printStackTrace(ps);
        } catch (NoSuchElementException e) {
            errorr.println("There is no such element.");
            errorr.println(e.getMessage());
            e.printStackTrace(ps);
        } catch (UnsupportedOperationException e) {
            errorr.println("An unsupported operation occured.");
            errorr.println(e.getMessage());
            e.printStackTrace(ps);
        } catch (NumberFormatException e) {
            errorr.println("Number Format Exception.");
            errorr.println(e.getMessage());
            e.printStackTrace(ps);
        }
    }
    errorr.close();
    outputt.close();
    scan.close();
}
}

如何遍历文本文件以打印到另一个文本文件中？

1 个答案: