Find files in a folder using Java

Question

What I need to do if Search a folder say C:\\example

I then need to go through each file and check to see if it matches a few start characters so if fil

Answer 1

• Matcher.find and Files.walk methods could be an option to search files in more flexible way
• String.format combines regular expressions to create search restrictions
• Files.isRegularFile checks if a path is't directory, symbolic link, etc.

Usage:

//Searches file names (start with "temp" and extension ".txt")
//in the current directory and subdirectories recursively
Path initialPath = Paths.get(".");
PathUtils.searchRegularFilesStartsWith(initialPath, "temp", ".txt").
                                       stream().forEach(System.out::println);

Source:

public final class PathUtils {

    private static final String startsWithRegex = "(? searchRegularFilesStartsWith(final Path initialPath, 
                             final String fileName, final String fileExt) throws IOException {
        return searchRegularFiles(initialPath, startsWithRegex + fileName, fileExt);
    }

    public static List searchRegularFilesEndsWith(final Path initialPath, 
                             final String fileName, final String fileExt) throws IOException {
        return searchRegularFiles(initialPath, fileName + endsWithRegex, fileExt);
    }

    public static List searchRegularFilesAll(final Path initialPath) throws IOException {
        return searchRegularFiles(initialPath, "", "");
    }

    public static List searchRegularFiles(final Path initialPath,
                             final String fileName, final String fileExt)
            throws IOException {
        final String regex = String.format(containsRegex, fileName, fileExt);
        final Pattern pattern = Pattern.compile(regex);
        try (Stream walk = Files.walk(initialPath.toRealPath())) {
            return walk.filter(path -> Files.isRegularFile(path) &&
                                       pattern.matcher(path.toString()).find())
                    .collect(Collectors.toList());
        }
    }

    private PathUtils() {
    }
}

Try startsWith regex for \txt\temp\tempZERO0.txt:

(?

Try endsWith regex for \txt\temp\ZERO0temp.txt:

temp(?=[\\.\\n])(?:[^\/\\]*(?=((?i)\.txt(?!.))))

Try contains regex for \txt\temp\tempZERO0tempZERO0temp.txt:

temp(?:[^\/\\]*(?=((?i)\.txt(?!.))))