从包含多个文件类型的Java目录中读取单个文件类型

Question

Is it possible to read single type of file (say like CSV or txt) from the directory containing multiple file types (say like cvs , txt , doc, xml, html, etc..)

My problem is I have to provide path of the mainDirectory as an input , which further has layers of subdirectories inside it. I specifically need to read and process CSV files within these directories as I further dive in.

I am done with multiple layers of folder traversing using recursion courtesy which I have the names and total count of the files within the mainDirectory. I am also done with logic to read and CSV files. All I need to do is to get path only of CSV files and process them.

i am using below mentioned code for traversing multiple folders and getting the name :-

package org.ashu.input;

import java.io.File;

/**
 *
 * @author ashutosh
 */
public class MultiDir {

    private int fileCount;

    public void readFile(File f){
        System.out.println(f.getPath());
        fileCount++;
    }

    public void readDir(File f){
        File subdir[] = f.listFiles();
        for(File f_arr : subdir){
            if(f_arr.isFile()){
                this.readFile(f_arr);
            }
            if(f_arr.isDirectory()){
                this.readDir(f_arr);
            }
        }
    }

    public static void main(String[] args){
        MultiDir md = new MultiDir();
        File mainDir = new File("/Users/ashutosh/Downloads/main_directory");
        md.readDir(mainDir);
        System.out.println(md.fileCount);//all file count = 1576, need to specifically get CSV
    }

}

Any suggestion please.

Answer 1

You can simply check the extension of the file in your readDir() method. The below looks for jpg, you can use your desired extension

public void readDir(File f){
    File subdir[] = f.listFiles();
    for(File f_arr : subdir){
        if(f_arr.isFile() && f_arr.getName().endsWith(".jpg")){
            this.readFile(f_arr);
        }
        if(f_arr.isDirectory()){
            this.readDir(f_arr);
        }
    }
}

Answer 2

This code will return every file matching the given extension (in your case .csv ):

public static List<File> getFiles(String extension, final File folder)
{

    extension = extension.toUpperCase();

    final List<File> files = new ArrayList<File>();
    for (final File file : folder.listFiles())
    {

        if (file.isDirectory())
            files.addAll(getFiles(extension, file));
        else if (file.getName().toUpperCase().endsWith(extension))
            files.add(file);

    }

    return files;

}