Java使用renameTo（file）在方法中重命名文件

Question

I am using this method that copies a file with altered info to the new one. I am simply attaching this code(that works as intended),in case my ignorance exceeds my expectations.

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();
                }

This is where I encounter a problem.The starting file deletes,but the final correctly altered file doesn't rename as intended.

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

Answer 1

I can confirm that the code below when executed results to:

• "Source.txt" file gets deleted
• "Destination.txt" gets created and contains characters as expected
• "Destination.txt" gets renamed to "Available_Devices.txt" keeping all its data intact

If this is not working on your system as described, check if your java program has the permissions to do the required manipulations on the files (if you are on linux try running your program with sudo? )

If your problem is different, please describe it in more detail.

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.");
                }


    }
}