java - java中读取特定文本行中的特定字符

Question

我正在开发一个程序，该程序涉及我必须搜索 .txt 文件中的特定行并将其中的字符串转换为其他内容。

例如，字符串实际上是由数字组成的，我想我可以将其转换为整数。最主要的是，例如第2行，存储了5位邮政编码。我需要根据数字将其转换为某些输出。换句话说，我需要数字 0-9 的变量，并根据每个数字输出特定的输出。

现在这是我必须提示用户输入文件中存储的信息的代码，并且可以读取和打印刚刚键入的所有信息，但我不确定如何处理其余的事情。

import java.io.*;
import java.util.*;
import java.io.FileReader;
import java.io.IOException;

public class ObjectTest2 {
public static void main(String [] args) throws FileNotFoundException, IOException {

    // The name of the file to open.
    String fileName = "information.txt";
    Scanner myScanner = new Scanner(System.in);

    try {
        // Assume default encoding.
        FileWriter fileWriter =
            new FileWriter(fileName);

        // Always wrap FileWriter in BufferedWriter.
        BufferedWriter bufferedWriter =
            new BufferedWriter(fileWriter);            
        // append a newline character.
        //This shit here prompts the user for information and stores it in seperate lines to be
        //called on by the later section.
        System.out.print("What is your name? ");
        bufferedWriter.write(myScanner.nextLine());
        bufferedWriter.newLine();
        System.out.print("What is your 5 digit zip code?");
        bufferedWriter.write(myScanner.nextLine());
        bufferedWriter.newLine();
        System.out.print("What is your +4 digit zip? ");
        bufferedWriter.write(myScanner.nextLine());
        bufferedWriter.newLine();
        System.out.print("What is your address? ");
        bufferedWriter.write(myScanner.nextLine());

        // Always close files.
        bufferedWriter.close();

        //reads the information file and prints what is typed
        BufferedReader reader = new BufferedReader(new FileReader("information.txt")); {
            while (true) {
                String line = reader.readLine();
                if (line == null) {
                    break;
                }
                System.out.println(line);
            }
        }           
    }
    catch(IOException ex) {
        System.out.println(
            "Error writing to file '"
            + fileName + "'");
        // Or we could just do this:
        // ex.printStackTrace();
    }
}
}

Answer 1

您别无选择，只能迭代文件的每一行并搜索字符串。如果您想根据行号从文件中获取一行字符串，请考虑创建一个方法。如果需要对同一个文件进行多次操作，并且文件内容没有变化，可以使用map根据行号来缓存文件内容。