How to Match Wildcard Strings When Locating Files in Java?

How to Locate Files Matching Wildcard Strings in Java

In Java, finding files that adhere to specific wildcard patterns is a common task. When given a wildcard string like "../Test?/sample*.txt", it's essential to identify the corresponding files that match this pattern.

One widely accepted method to tackle this challenge is by leveraging the WildcardFileFilter class from the Apache Commons IO library. This filter enables you to specify wildcard expressions that define the file search criteria.

To illustrate its usage, let's look at an example:

import org.apache.commons.io.FileUtils;

File dir = new File(".");
FileFilter fileFilter = new WildcardFileFilter("sample*.java");
File[] files = dir.listFiles(fileFilter);
for (File file : files) {
    System.out.println(file);
}

In this scenario, the filter will find all files in the current directory that match the pattern "sample*.java", including files like "sample22b.java" and "sample-spiffy.java".

However, if you need to match more complex paths with wildcard characters and subdirectories, a more explicit approach is required. One option is to iterate through the list of subdirectories and apply the wildcard filter to each subdirectory separately:

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

This approach ensures that files located within subdirectories matching the "Test*" pattern are also considered in the search results.

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