Java String.replaceFirst() 问题

Question

嗨，我正在尝试编写代码来读取包含一首诗的文件。然后它将每行中的第一个“您”更改为“我们”。我一直在尝试使用replaceFirst()、replace()、replaceAll();然而，没有一个人能够替代任何东西。

 import java.io.*;
import java.util.Scanner;//imports

public class TextEditorTester 
{
    private static boolean line_change;

   public static void main(String[] args) throws FileNotFoundException
   {
       String line = "";
       File inFile = new File("OldPoem.txt");
       Scanner in = new Scanner(inFile);
       PrintWriter out = new PrintWriter("NewPoem.txt");
       while(in.hasNextLine()){
           line = in.nextLine();
           line.replace("you", "we");
           out.println(line);
       }
       out.close();
       File newFile = new File("NewPoem.txt");
       Scanner newOne = new Scanner(newFile);
       System.out.println(newOne.nextLine());
       System.out.println("Expected: Have we ever tried to enter the long black branches of other lives");
   }
}

Answer 1

replace 方法返回新行，它无法修改您调用它的对象。所以尝试一下:

line = line.replace("you", "we");