Java使用renameTo（file）在方法中重命名文件

Question

我正在使用这种方法将具有更改信息的文件复制到新文件。 如果我的无知超出了我的期望，我只是附上此代码（可以正常工作）。

public void Writedevices(String Start)throws IOException{
                File S = null;
                File D = null;
                BufferedReader reader = null;
                String line;
                BufferedWriter writer = null;
                PrintWriter Newfile = new PrintWriter("Destination.txt","UTF-8");
                int i=0;
                try{
                        S = new File(Start);
                        D = new File("Destination.txt");
                    }
                    catch (NullPointerException e){
                    System.err.println("File not found.");
                    }

                try{
                    reader = new BufferedReader(new FileReader(S));
                    writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(D), "utf-8"));
                    line = reader.readLine();
                    while(line != null){
                        if(!line.toLowerCase().contains("pieces")){
                            writer.write(line);
                            writer.append(System.getProperty("line.separator"));
                        }
                        else{
                            writer.write("            PIECES "+Availability.get(i));
                            writer.append(System.getProperty("line.separator"));
                            i++;
                        }
                        line=reader.readLine();
                    }
                }  
                catch (FileNotFoundException e ){
                System.err.println("Error opening file!");
                }
                finally{
                    writer.close();
                    reader.close();
                }

这是我遇到的问题。起始文件已删除，但最终正确更改的文件未按预期重命名。

S.delete();
                File Name = new File("Available_Devices.txt");
                if(D.renameTo(Name)){
                System.out.println("Device list availability update succesfull.");
                        }
            }

Answer 1

我可以确认以下代码在执行后会导致：

• "Source.txt"文件被删除
• 创建"Destination.txt"并包含预期的字符
• "Destination.txt"重命名为"Available_Devices.txt"保持其所有数据不变

如果这在您所描述的系统上不起作用，请检查您的Java程序是否具有对文件进行所需操作的权限（如果您在linux上，请尝试使用sudo运行程序）。

如果您的问题不同，请更详细地描述。

package tempProject;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.OutputStreamWriter;

public class FileTransformer2 {
    public static void main(String[] args) {
        try {
            Writedevices("Source.txt");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void Writedevices(String Start) throws IOException {
        File S = null;
        File D = null;
        BufferedReader reader = null;
        String line;
        BufferedWriter writer = null;
        int i = 0;
        try {
            S = new File(Start);
            D = new File("Destination.txt");
        } catch (NullPointerException e) {
            System.err.println("File not found.");
        }

        try {
            reader = new BufferedReader(new FileReader(S));
            writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(D), "utf-8"));
            line = reader.readLine();
            while (line != null) {
                if (!line.toLowerCase().contains("pieces")) {
                    writer.write(line);
                    writer.append(System.getProperty("line.separator"));
                } else {
                    // writer.write(" PIECES "+Availability.get(i));
                    writer.append(System.getProperty("line.separator"));
                    i++;
                }
                line = reader.readLine();
            }

        } catch (FileNotFoundException e) {
            System.err.println("Error opening file!");
        } finally {
            writer.close();
            reader.close();

        }

        S.delete();
        File Name = new File("Available_Devices.txt");
        if(D.renameTo(Name)){
        System.out.println("Device list availability update succesfull.");
                }


    }
}