Question

我正在制作这个应该从输入文件读取然后创建输出文件的程序。

输入文件（portlandvip2.txt）：

法院50

专栏10

Club 25

Rascal Conway 10 Box

Loretta Barrett 3 Court

Loras Tyrell 5俱乐部

Margaery Tyrell 8 Box

Roslin Frey 2 Box

Sansa Stark 2 Club

Jon Snow 5 Club

Edmure Tully 3 Box

Joffrey Baratheon 20 Court

Stannis Baratheon 4 Club

Jaime Lannister 2 Box

Cersei Lannister 1 Court

Beric Dondarrion 8 Court

Balon Greyjoy 16 Box

Olenna Tyrell 4 Court

梅斯泰瑞尔5盒

Tyrion Lannister 2俱乐部

Sandor Clegane 2 Court

Gregor Clegane 6 Club

Samwell Tarly 3 Club

Petyr Baelish 6 Court

这是一个输出文件应该是什么样子的示例（portland2out.txt）：

法院50美元

Box $ 10

Club $ 25

Rascal Conway $ 100.00

Loretta Barrett $ 150.00

我遇到的问题是打印的所有输出文件都是Petyr Baelish。

到目前为止，这是该计划：

import java.util.Scanner;
import java.io.*;
import java.io.Writer;


public class WebberProject2
{

    public static void main(String[] args) throws IOException
    {
        Scanner inputFile = new Scanner(System.in); 

        File inputScanner = new File("portlandvip2.txt");

        Scanner scanner = new Scanner(new File("portlandvip2.txt"));
        while(scanner.hasNext())
        {
            String firstName = scanner.next();
            String lastName = scanner.next();

            PrintWriter outputFile = new PrintWriter("portland2out.txt");

            outputFile.println(" " + firstName + " " + lastName); 
            scanner.nextLine();

            inputFile.close();
            outputFile.close();
        }
    }
}

Answer 1

您正在循环中打开和关闭输出文件，每次执行循环时都会重写一行。在循环外部使用PrintWriter及其close（）方法。此外，您还有其他资源也在循环中关闭。试试这种方法：

// ...


Scanner inputFile = new Scanner(System.in); 
File inputScanner = new File("portlandvip2.txt");
Scanner scanner = new Scanner(new File("portlandvip2.txt"));
PrintWriter outputFile = new PrintWriter("portland2out.txt");

while(scanner.hasNext())
{
    String firstName = scanner.next();
    String lastName = scanner.next();

    outputFile.println(" " + firstName + " " + lastName); 
    scanner.nextLine();

}
outputFile.close();
inputFile.close();
scanner.close();
// ...

Answer 2

您的代码看起来不完整。虽然循环未关闭。你也在关闭循环中的文件，这会抛出异常。使用以下代码作为基础并根据您的要求进行调整。例如，使用Scanner方法nextInt（）来读取数字标记，并在写入输出文件时在它们前面加上$符号。

    import java.io.File;
    import java.io.IOException;
    import java.io.PrintWriter;
    import java.util.Scanner;


    public class TestScanner{

    public static void main(String[] args)
    {
        Scanner scanner = null;
        PrintWriter outputFile = null;
        try{
        scanner = new Scanner(new File("portlandvip2.txt"));
        outputFile = new PrintWriter("portland2out.txt");
        String firstName, lastName;
        int num = 0;
        while(scanner.hasNext())
        {
             firstName = scanner.next();
             if(scanner.hasNextInt()){
                 num = scanner.nextInt();
             }
             lastName = scanner.next();
             outputFile.println(" " + firstName + " " + lastName + " $ " + num); 
             scanner.nextLine();

        }
       }catch(IOException e){
           System.out.println("exception:"+e);
       }finally{
           scanner.close();
           outputFile.close();
       }
    }
    }

如何在读取输入文件后操作输出文件？

2 个答案: