Java Files walk examples
Java File.walk method is available in java 8. It is very useful to traverse the the content of a file tree. Walks goes in a depth first fashion and return a Stream object. We can then work with the stream to get the required result. Like we can filter only directories, find files matching some name etc. This article covers three example of using File.walk to list all the directories, files and both.
List all the folders
List all the directories/folders inside the location specified by path.
public List getFolders(String path) throws IOException {
Stream walk = Files.walk(Paths.get(path));
List result = walk.filter(Files::isDirectory).map(x -> x.getFileName().toString())
.collect(Collectors.toList());
result.forEach(System.out::println);
walk.close();
return result;
}List all files
Similar to above method, but the filter condition is different. Here we are filtering only regular files with Files::isRegularFile.
public List getFiles(String path) throws IOException {
Stream walk = Files.walk(Paths.get(path));
List result = walk.filter(Files::isRegularFile).map(x -> x.getFileName().toString())
.collect(Collectors.toList());
result.forEach(System.out::println);
walk.close();
return result;
}Files and Directories
Following method will list all the directories: with files inside it. It is similar to linux command ls *.
public List getFoldersAndFiles(String path) throws IOException {
Stream walk = Files.walk(Paths.get(path));
List result = walk.map(x -> {
if (Files.isDirectory(x)) {
return x.getFileName().toString() + ":";
} else
return x.getFileName().toString();
}).collect(Collectors.toList());
result.forEach(System.out::println);
walk.close();
return result;
}
