Java：重命名文件-无法正确重命名文件

Question

The following Java code renames files but it does not rename the way I wanted it to. I want the rename files to start from beginning in the directory to the end per the “part” numbers (not the time it was added in inside a particular directory), but it does not do so. Is there an “if” check I can put, like: if filename.contains(j) then process this?

import java.io.File;

public class RenameFile2 {

    public static void main(String[] args) {

        String absolutePath1 = "1 to 4";
        String absolutePath2 = "6 to 9";
        String absolutePath3 = "10 to 99";
        String absolutePath4 = "100 to 224";

        File dir1 = new File(absolutePath1);
        File dir2 = new File(absolutePath2);
        File dir3 = new File(absolutePath3);
        File dir4 = new File(absolutePath4);

        File[] filesInDir1 = dir1.listFiles();
        File[] filesInDir2 = dir2.listFiles();
        File[] filesInDir3 = dir3.listFiles();
        File[] filesInDir4 = dir4.listFiles();

        int i1 = 1;

        for(File file:filesInDir1) {
            String name = file.getName();
            String newName = "550 00510 00" + i1 + ".pdf";
            String newPath = absolutePath1 + "\\" + newName;
            file.renameTo(new File(newPath));
            System.out.println(name + " changed to " + newName);
            i1++;
        }

        int i2 = 6;
        for(File file:filesInDir2) {
            String name = file.getName();
            String newName = "550 00510 00" + i2 + ".pdf";
            String newPath = absolutePath2 + "\\" + newName;
            file.renameTo(new File(newPath));
            System.out.println(name + " changed to " + newName);
            i2++;
        }

        int i3 = 10;
        for(File file:filesInDir3) {
            String name = file.getName();
            String newName = "550 00510 0" + i3 + ".pdf";
            String newPath = absolutePath3 + "\\" + newName;
            file.renameTo(new File(newPath));
            System.out.println(name + " changed to " + newName);
            i3++;
        }

        int i4 = 100;
        //int j = 99;
        for(File file:filesInDir4) {
            String name = file.getName();
/*            if(name.contains(j))
                {
                }
*/
            String newName = "550 00510 " + i4 + ".pdf";
            String newPath = absolutePath4 + "\\" + newName;
            file.renameTo(new File(newPath));
            System.out.println(name + " changed to " + newName);
            i4++;
            }
        }
    }

Answer 1

You need to sort the files once you list them, the listFiles() does not guarentee any order.

File[] filesInDir1 = dir1.listFiles();
Arrays.sort(filesInDir1);

You may need to implement a Comparator and call Arrays.sort(filesList, comparator) in order to have them custom sorted.

Once you have the files in sorted order, you can apply the rename logic as you wanted.

Another improvement would be, if you want to list only files with a pattern, you can filter while listing.

final String pattern = "regexpattern";
 dir1.listFiles(new FilenameFilter(){
                           public boolean accept( File dir, String name ) {
                               return name.matches( pattern );
                           }
                        });

Answer 2

In the documentation for .listFiles() , it says:

There is no guarantee that the name strings in the resulting array will appear in any specific order; they are not, in particular, guaranteed to appear in alphabetical order.

You need to sort the array in the order you want to process them in a particular order.

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Additional notes and suggestions:

• String.contains() takes a String as an argument, not an int . You have this code commented out in your question.
• Use the constructor for File to produce the new path instead of string concatenation: File newPath = new File(dir1, newName);