Let's say, I have a folder called maps and inside maps I have map1.txt, map2.txt, and map3.txt. How can I use Java and the BufferReader to read all of the .txt files in folder maps (if it is at all possible)?
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Possible duplicate of Read all files in a folderjsingh– jsingh2017-01-16 17:30:37 +00:00Commented Jan 16, 2017 at 17:30
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7 Answers
Something like the following should get you going, note that I use apache commons FileUtils instead of messing with buffers and streams for simplicity...
File folder = new File("/path/to/files");
File[] listOfFiles = folder.listFiles();
for (int i = 0; i < listOfFiles.length; i++) {
File file = listOfFiles[i];
if (file.isFile() && file.getName().endsWith(".txt")) {
String content = FileUtils.readFileToString(file);
/* do somthing with content */
}
}
4 Comments
test
Ah. Thanks... but a note: would it make it easier to manage if all of the files were named mapNUMBER.txt? As in map3.txt, map4.txt, etc.
paul
This code won't work as is because there's no declaration of the variable 'file' used on line 6. Not sure why you would write it up this way, maybe it's supposed to be more pseudocode style, but file should be replaced with listOfFiles[i], or the file variable should be declared if it's going to be used.
Dolda2000
Just for the record,
for(File file : folder.listFiles()) is quite a bit shorter and nicer. :)
Andrew White
@Dolda2000 agreed, I am not real sure why I answered this way. Perhaps I pulled an existing example.
I would take @Andrew White answer (+1 BTW) one step further, and suggest you would use FileNameFilter to list only relevant files:
FilenameFilter filter = new FilenameFilter() {
public boolean accept(File dir, String name) {
return name.endsWith(".txt");
}
};
File folder = new File("/path/to/files");
File[] listOfFiles = folder.listFiles(filter);
for (int i = 0; i < listOfFiles.length; i++) {
File file = listOfFiles[i];
String content = FileUtils.readFileToString(file);
// do something with the file
}
4 Comments
Kenny Cason
@Shahryar it's not a redundant answer, it's a different and valid answer.
Shahryar
@KennyCason As I see it's just like previous answer! What is the advantage of using FileNameFilter?
Kenny Cason
@Shahryar yes, which is imo an equal, and possibly, a cleaner example. It's also good to know the existence of
other solutions. You'll see on SO that there are many similar, but different solutions to a problem are supplied.Shahryar
@KennyCason "It's also good to know the existence of other solutions" good word :-)
final File folder = new File("C:/Dev Tools/apache-tomcat-6.0.37/webapps/ROOT/somefile");
for (final File fileEntry : folder.listFiles()) {
System.out.println("FileEntry Directory "+fileEntry);
With NIO you can do the following:
Files.walk(Paths.get("/path/to/files"))
.filter(Files::isRegularFile)
.filter(path -> path.getFileName().toString().endsWith(".txt"))
.map(FileUtils::readFileToString)
// do something
To read the file contents you may use Files#readString but, as usual, you need to handle IOException inside lambda expression.
1 Comment
Dmitry Zinkevich
Surround with
try/catch ?I think it's good way to read all .txt files from maps and sub folder's
private static void addfiles (File input,ArrayList<File> files)
{
if(input.isDirectory())
{
ArrayList <File> path = new ArrayList<File>(Arrays.asList(input.listFiles()));
for(int i=0 ; i<path.size();++i)
{
if(path.get(i).isDirectory())
{
addfiles(path.get(i),files);
}
if(path.get(i).isFile())
{
String name=(path.get(i)).getName();
if(name.lastIndexOf('.')>0)
{
int lastIndex = name.lastIndexOf('.');
String str = name.substring(lastIndex);
if(str.equals(".txt"))
{
files.add(path.get(i));
}
}
}
}
}
if(input.isFile())
{
String name=(input.getName());
if(name.lastIndexOf('.')>0)
{
int lastIndex = name.lastIndexOf('.');
String str = name.substring(lastIndex);
if(str.equals(".txt"))
{
files.add(input);
}
}
}
}
Comments
If you want a better way of doing this using the new java.nio api, then this is the way, taken from the java docs
Path dir = ...;
try (DirectoryStream<Path> stream =
Files.newDirectoryStream(dir, "*.txt")) {
for (Path entry: stream) {
System.out.println(entry.getFileName());
}
} catch (IOException x) {
// IOException can never be thrown by the iteration.
// In this snippet, it can // only be thrown by newDirectoryStream.
System.err.println(x);
}
Comments
Using only JDK, If all your files are in one directory:
File dir = new File("path/to/files/");
for (File file : dir.listFiles()) {
Scanner s = new Scanner(file);
// do something with file
s.close();
}
To exclude files, you can use listFiles(FileFilter)