How to find files that match a wildcard string in Java?

Question

This should be really simple. If I have a String like this:

../Test?/sample*.txt

then what is a generally-accepted way to get a list of files that match this pattern? (e.g. it should match ../Test1/sample22b.txt and ../Test4/sample-spiffy.txt but not ../Test3/sample2.blah or ../Test44/sample2.txt)

I've taken a look at org.apache.commons.io.filefilter.WildcardFileFilter and it seems like the right beast but I'm not sure how to use it for finding files in a relative directory path.

I suppose I can look the source for ant since it uses wildcard syntax, but I must be missing something pretty obvious here.

(edit: the above example was just a sample case. I'm looking for the way to parse general paths containing wildcards at runtime. I figured out how to do it based on mmyers' suggestion but it's kind of annoying. Not to mention that the java JRE seems to auto-parse simple wildcards in the main(String[] arguments) from a single argument to "save" me time and hassle... I'm just glad I didn't have non-file arguments in the mix.)

Answer 1

Try FileUtils from Apache commons-io (listFiles and iterateFiles methods):

File dir = new File(".");
FileFilter fileFilter = new WildcardFileFilter("sample*.java");
File[] files = dir.listFiles(fileFilter);
for (int i = 0; i < files.length; i++) {
   System.out.println(files[i]);
}

To solve your issue with the TestX folders, I would first iterate through the list of folders:

File[] dirs = new File(".").listFiles(new WildcardFileFilter("Test*.java");
for (int i=0; i<dirs.length; i++) {
   File dir = dirs[i];
   if (dir.isDirectory()) {
       File[] files = dir.listFiles(new WildcardFileFilter("sample*.java"));
   }
}

Quite a 'brute force' solution but should work fine. If this doesn't fit your needs, you can always use the RegexFileFilter.

Answer 2

Consider DirectoryScanner from Apache Ant:

DirectoryScanner scanner = new DirectoryScanner();
scanner.setIncludes(new String[]{"**/*.java"});
scanner.setBasedir("C:/Temp");
scanner.setCaseSensitive(false);
scanner.scan();
String[] files = scanner.getIncludedFiles();

You'll need to reference ant.jar (~ 1.3 MB for ant 1.7.1).

Answer 3

Here are examples of listing files by pattern powered by Java 7 nio globbing and Java 8 lambdas:

    try (DirectoryStream<Path> dirStream = Files.newDirectoryStream(
            Paths.get(".."), "Test?/sample*.txt")) {
        dirStream.forEach(path -> System.out.println(path));
    }

or

    PathMatcher pathMatcher = FileSystems.getDefault()
        .getPathMatcher("regex:Test./sample\\w+\\.txt");
    try (DirectoryStream<Path> dirStream = Files.newDirectoryStream(
            new File("..").toPath(), pathMatcher::matches)) {
        dirStream.forEach(path -> System.out.println(path));
    }

Answer 4

Since Java 8 you can use Files#find method directly from java.nio.file.

public static Stream<Path> find(Path start,
                                int maxDepth,
                                BiPredicate<Path, BasicFileAttributes> matcher,
                                FileVisitOption... options)

Example usage

Files.find(startingPath,
           Integer.MAX_VALUE,
           (path, basicFileAttributes) -> path.toFile().getName().matches(".*.pom")
);

Or an example of putting items in a simple string collection:

import java.io.UncheckedIOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.Collection;
import java.util.stream.Stream;

        final Collection<String> simpleStringCollection = new ArrayList<>();
        
        String wildCardValue = "*.txt";

        final Path dir = Paths.get(".");

        try {
            Stream<Path> results = Files.find(dir,
                    Integer.MAX_VALUE,
                    (path, basicFileAttributes) -> path.toFile().getName().matches(wildCardValue)
            );

            results.forEach(p -> simpleStringCollection.add(p.toString()));
        } catch (IOException e) {
            throw new UncheckedIOException(e);
        }

Answer 5

You could convert your wildcard string to a regular expression and use that with String's matches method. Following your example:

String original = "../Test?/sample*.txt";
String regex = original.replace("?", ".?").replace("*", ".*?");

This works for your examples:

Assert.assertTrue("../Test1/sample22b.txt".matches(regex));
Assert.assertTrue("../Test4/sample-spiffy.txt".matches(regex));

And counter-examples:

Assert.assertTrue(!"../Test3/sample2.blah".matches(regex));
Assert.assertTrue(!"../Test44/sample2.txt".matches(regex));

Answer 6

Might not help you right now, but JDK 7 is intended to have glob and regex file name matching as part of "More NIO Features".

Answer 7

The wildcard library efficiently does both glob and regex filename matching:

http://code.google.com/p/wildcard/

The implementation is succinct -- JAR is only 12.9 kilobytes.

Answer 8

Simple Way without using any external import is to use this method

I created csv files named with billing_201208.csv ,billing_201209.csv ,billing_201210.csv and it looks like working fine.

Output will be the following if files listed above exists

found billing_201208.csv
found billing_201209.csv
found billing_201210.csv

    //Use Import ->import java.io.File
        public static void main(String[] args) {
        String pathToScan = ".";
        String target_file ;  // fileThatYouWantToFilter
        File folderToScan = new File(pathToScan); 

    File[] listOfFiles = folderToScan.listFiles();

     for (int i = 0; i < listOfFiles.length; i++) {
            if (listOfFiles[i].isFile()) {
                target_file = listOfFiles[i].getName();
                if (target_file.startsWith("billing")
                     && target_file.endsWith(".csv")) {
                //You can add these files to fileList by using "list.add" here
                     System.out.println("found" + " " + target_file); 
                }
           }
     }    
}

Answer 9

As posted in another answer, the wildcard library works for both glob and regex filename matching: http://code.google.com/p/wildcard/

I used the following code to match glob patterns including absolute and relative on *nix style file systems:

String filePattern = String baseDir = "./";
// If absolute path. TODO handle windows absolute path?
if (filePattern.charAt(0) == File.separatorChar) {
    baseDir = File.separator;
    filePattern = filePattern.substring(1);
}
Paths paths = new Paths(baseDir, filePattern);
List files = paths.getFiles();

I spent some time trying to get the FileUtils.listFiles methods in the Apache commons io library (see Vladimir's answer) to do this but had no success (I realise now/think it can only handle pattern matching one directory or file at a time).

Additionally, using regex filters (see Fabian's answer) for processing arbitrary user supplied absolute type glob patterns without searching the entire file system would require some preprocessing of the supplied glob to determine the largest non-regex/glob prefix.

Of course, Java 7 may handle the requested functionality nicely, but unfortunately I'm stuck with Java 6 for now. The library is relatively minuscule at 13.5kb in size.

Note to the reviewers: I attempted to add the above to the existing answer mentioning this library but the edit was rejected. I don't have enough rep to add this as a comment either. Isn't there a better way...

Answer 10

Glob of Java7: Finding Files. (Sample)

Answer 11

You should be able to use the WildcardFileFilter. Just use System.getProperty("user.dir") to get the working directory. Try this:

public static void main(String[] args) {
File[] files = (new File(System.getProperty("user.dir"))).listFiles(new WildcardFileFilter(args));
//...
}

You should not need to replace * with [.*], assuming wildcard filter uses java.regex.Pattern. I have not tested this, but I do use patterns and file filters constantly.

Answer 12

The Apache filter is built for iterating files in a known directory. To allow wildcards in the directory also, you would have to split the path on '\' or '/' and do a filter on each part separately.

Answer 13

Using Java streams only

Path testPath = Paths.get("C:\");

Stream<Path> stream =
                Files.find(testPath, 1,
                        (path, basicFileAttributes) -> {
                            File file = path.toFile();
                            return file.getName().endsWith(".java");
                        });

// Print all files found
stream.forEach(System.out::println);

Answer 14

Implement the JDK FileVisitor interface. Here is an example http://wilddiary.com/list-files-matching-a-naming-pattern-java/

Answer 15

Util Method:

public static boolean isFileMatchTargetFilePattern(final File f, final String targetPattern) {
        String regex = targetPattern.replace(".", "\\.");  //escape the dot first
        regex = regex.replace("?", ".?").replace("*", ".*");
        return f.getName().matches(regex);

    }

jUnit Test:

@Test
public void testIsFileMatchTargetFilePattern()  {
    String dir = "D:\\repository\\org\my\\modules\\mobile\\mobile-web\\b1605.0.1";
    String[] regexPatterns = new String[] {"_*.repositories", "*.pom", "*-b1605.0.1*","*-b1605.0.1", "mobile*"};
    File fDir = new File(dir);
    File[] files = fDir.listFiles();

    for (String regexPattern : regexPatterns) {
        System.out.println("match pattern [" + regexPattern + "]:");
        for (File file : files) {
            System.out.println("\t" + file.getName() + " matches:" + FileUtils.isFileMatchTargetFilePattern(file, regexPattern));
        }
    }
}

Output:

match pattern [_*.repositories]:
    mobile-web-b1605.0.1.pom matches:false
    mobile-web-b1605.0.1.war matches:false
    _remote.repositories matches:true
match pattern [*.pom]:
    mobile-web-b1605.0.1.pom matches:true
    mobile-web-b1605.0.1.war matches:false
    _remote.repositories matches:false
match pattern [*-b1605.0.1*]:
    mobile-web-b1605.0.1.pom matches:true
    mobile-web-b1605.0.1.war matches:true
    _remote.repositories matches:false
match pattern [*-b1605.0.1]:
    mobile-web-b1605.0.1.pom matches:false
    mobile-web-b1605.0.1.war matches:false
    _remote.repositories matches:false
match pattern [mobile*]:
    mobile-web-b1605.0.1.pom matches:true
    mobile-web-b1605.0.1.war matches:true
    _remote.repositories matches:false

Answer 16

Why not use do something like:

File myRelativeDir = new File("../../foo");
String fullPath = myRelativeDir.getCanonicalPath();
Sting wildCard = fullPath + File.separator + "*.txt";

// now you have a fully qualified path

Then you won't have to worry about relative paths and can do your wildcarding as needed.

Answer 17

The most simple and easy way by using the io library's File class would be :

    String startingdir="The directory name";
    String filenameprefix="The file pattern"
    File startingDirFile=new File(startingdir); 
    final File[] listFiles=startingDirFile.listFiles(new FilenameFilter() {
        public boolean accept(File arg0,String arg1)
        {System.out.println(arg0+arg1);
            return arg1.matches(filenameprefix);}
        });
    System.out.println(Arrays.toString(listFiles));