在特定目录中查找文件名并存储在数组列表中的代码

Question

Good morning everyone,

I'm stuck here with a code that I'm trying to make work. The goal of this code is to make a recursive algorithm to find all files that matched a target file name. Each string should store the pathname to the matching file. Return null if no matching files are found. Here is what I have so far:

import java.io.File;
import java.util.ArrayList;

public class ArrayListFiles 
{
    public static ArrayList searchForFile
    (File dir, ArrayList filePaths, String target)
    {
        if (!dir.isDirectory())
            return null;
        else 
        {
            File[] files=dir.listFiles();
            for (int index = 0; index < filePaths; index++)
            {
                if(files[index].isFile())
                {
                    if(files[index].getName().equals(target))
                    {
                        filePaths.add(files[index].toString());
                    }
                }
            else if(files[index].isDirectory())
                searchForFile(files[index], filePaths, target);
            }
        }
    return filePaths;
    }
    public static void main(String[] args)
    {
        ArrayList filePaths = new ArrayList();
        File rootFolder = new File("F:\\java");
        String targetFile = "sample.txt";
        filePaths = searchForFile(rootFolder, filePaths, targetFile);
        if(filePaths==null)
            System.out.println("No file is found");
        else
        {
            for (String string : filePaths)
            {
                System.out.println(string);
            }
        }

    }
}

I am very new to programming and apologize in advance if I'm missing something very obvious. Thank you in advance and have a great day!

Answer 1

To resolve this error "Type mismatch: cannot convert from element type Object to String" for "for (String string : filePaths). " change your code to this :

ArrayList<String> filePaths = new ArrayList<String>();
        File rootFolder = new File("F:\\java");
        String targetFile = "sample.txt";
        filePaths = searchForFile(rootFolder, filePaths, targetFile);
        if(filePaths==null)
            System.out.println("No file is found");
        else
        {
            for (String string : filePaths)
            {
                System.out.println(string);
            }
        }

FilePaths is an arraylist and it should be as follows :

 for (int index = 0; index < files.length; index++)

Hope this helps .

Answer 2

This is probably your problem:

int index = 0; index < filePaths; index++

FilePaths is an arraylist and you're using it as integer. You probably wanted to iterate through files? Try

int index = 0; index < files.length; index++