I want to list and print them out my src folder. But program is listing all files like .bin .classpat .project. I want to list and print only .ncat extension files. How can i do that ?
File f = null;
String[] paths;
try{
f = new File("C:/Users/BURAK NURÇİÇEK/workspace/cs 222");
paths = f.list();
for(String path:paths){
System.out.println(path);
}
}catch(Exception e){
e.printStackTrace();
}
You can define a FileNameFilter :
String[] list = dir.list(new FilenameFilter() {
#Override
public boolean accept(File file, String name) {
return name.endsWith("suffix");
}
});
Easy way would be to check if the path ends with the extension as follows:
File f = null;
String[] paths;
try{
f = new File("C:/Users/BURAK NURÇİÇEK/workspace/cs 222");
paths = f.list();
for(String path:paths){
if(path.toLowerCase().endsWith(".ncat")){
System.out.println(path);
}
}
}catch(Exception e){
e.printStackTrace();
}
Welcome to Stack Overflow.
Take a look at the String.endsWith(String suffix) method (see
here)
and make use of an if-condition.
Update
There is a better solution to this problem. Because this is a homework question (as the questioner mentioned) I will continue to elaborate the obvious way. One may google for FileFilter if he is required to use the "more professional" way.
Moving on: You are iterating over all files that are "stored" inside your paths variable (the for-loop). Inside the loop you are currently printing every file name. What you want to do, is to check if a file ends with the desired extension. If this condition is true, you can print it. If not: don't do anything.
try this
public void filter(){
String[] paths;
try{
f = new File("C:/Users/BURAK NURÇİÇEK/workspace/cs 222");
paths = f.list(new FilenameFilter() {
#Override
public boolean accept(File file, String name) {
return name.endsWith("txt");
}
});
for(String path:paths){
System.out.println(path);
}
}catch(Exception e){
e.printStackTrace();
}
}
Related
Good day.
I was wondering if java.io.File.listFiles(FilenameFilter filter) returns an already sorted object.
Here is my code:
String[] files = FIUtil.getFilesList(FIConstants.getIFDirectory(filePrefix),
FIConstants.VALID_INPUT_FILE_SUFFIX,filePrefix);
log.debug("=== LOOKING FOR FILES IN ===" + FIConstants.getIFDirectory(filePrefix));
log.debug("=== Inside directory ===");
for(int i=0;i<files.length;i++){
log.debug("=== "+files[i]); }
public static String[] getFilesList(String directory, final String suffix,String prefix)
{
try {
File fileObject = new File(directory);
return fileObject.list((new FilenameFilter() {
#Override
public boolean accept(File dir, String name) {
return name.startsWith(prefix) && name.endsWith(suffix);
}
}));
}
catch (SecurityException se) {
}
return null;
}
My files in the directory are not sorted.
But when I check the listing of files in my logs, they are already sorted.
As explained in File.listFiles() Javadoc there is no order guranteed
There is no guarantee that the name strings in the resulting array will appear in any specific order; they are not, in particular, guaranteed to appear in alphabetical order.
No, it does not sort by name, date or anything.
I need to find a file name from the list of filenames and to initiate two methods according to the found result. I tried:
FileList result = service.files().list()
.setPageSize(10)
.setFields("nextPageToken, files(id, name)")
.execute();
List<File> files = result.getFiles();
if (files == null || files.size() == 0) {
System.out.println("No files found.");
} else {
System.out.println("Files:");
for (File file : files) {
System.out.printf("%s (%s)\n", file.getName(), file.getId());
Boolean found = files.contains("XYZ");
if(found)
{
insertIntoFolder();
} else {
createFolder();
}
}
}
I need to find XYZ (the filename) from a list of file names (like sjh, jsdhf, XYZ, ASDF). Once I've found it I need to stop the search. If the name doesn't match the list of names I need to create a folder only once after checking all names from that list.
Boolean found = files.contains("XYZ");
This line is problematic. files is a list of File objects, none of which will match the String "XYX". List.contains() essentially calls Object.equals() on every element of the list, and File.equals("XYZ") will always return false.
If you're programming in an IDE like Eclipse it should show a warning on this line, since it's a bug that can be detected at compile-time.
To determine if a File in a List<File> has a filename matching a given string you need to operate on the filename itself, so the above line should instead be:
boolean found = file.getName().equals("XYZ");
Depending on what exactly you're trying to match you might want to use .getName(), .getAbsolutePath(), or .toString().
It's also a good idea to use the Path API introduced in Java 7, rather than File, which is essentially a legacy class at this point.
If you want a more elegant solution than manually looping over files looking for a match you can use Files.newDirectoryStream(Path, Filter) which allows you to define a Filter predicate that only matches certain files, e.g.
Files.newDirectoryStream(myDirectory, p -> p.getFileName().toString().equals("XYZ"))
File.list(FilenameFilter) is a similar feature for working with File objects, but again, prefer to use the Path API if possible.
Here is a example:
/**
* return true if file is in filesList else return false
*/
static boolean isFileInList(File file, List<File> filesList) {
for(File f: filesList) {
if (f.equals(file)) {
return true;
}
}
return false;
}
public static void main(String[] args) {
List<File> files;// the filelist; make sure assign these two variable.
File file; // the file you want to test.
if (isFileInList(file, files)) {
//file is presented
} else {
//file is not presented
createFolder();
}
}
package test;
import java.io.File;
import java.io.FilenameFilter;
import java.io.IOException;
public class DirectoryContents {
public static void main(String[] args) throws IOException {
File f = new File("."); // current directory
FilenameFilter textFilter = new FilenameFilter() {
public boolean accept(File dir, String name) {
String lowercaseName = name.toLowerCase();
if (lowercaseName.endsWith(".txt")) {
return true;
} else {
return false;
}
}
};
File[] files = f.listFiles(textFilter);
for (File file : files) {
if (file.isDirectory()) {
System.out.print("directory:");
} else {
System.out.print(" file:");
}
System.out.println(file.getCanonicalPath());
}
}
}
am trying to compare all the values in my arraylist with all the files in my c:drive
but the code below does not work
List<String> list = new ArrayList<String>();
list.add("*.txt,*.docx");
File file = new File("c:\\*.txt");
if (file.equals(list)) {
System.out.println("file was found");
}else{System.out.println("nothing was found");
}
so the idea is that anytime i run my the code my arraylist would compare itself with my c: drive and list all files that has the extension of "docx and txt" out.
i realised that when i use wildcards it didn't work.
What you need is a FileNameFilter to get all files that pertain to your requirements
Here is an example of getting all *.txt files from current directory. You can implement FileNameFilter to create your own filter that will work on your List.
File f = new File("."); // current directory
FilenameFilter textFilter = new FilenameFilter() {
public boolean accept(File dir, String name) {
String lowercaseName = name.toLowerCase();
if (lowercaseName.endsWith(".txt")) {
return true;
} else {
return false;
}
}
};
File[] files = f.listFiles(textFilter);
Hope this helps.
Is it possible to read all the names of folders (not sub-folders) inside a directory and save the list in an ArrayList, etc ?
e.g- if a directory has the following folders inside it- CLIENT1, CLIENT2, CLIENT3, etc.
I want the ArrayList to be something like this- [CLIENT1, CLIENT2, CLIENT3, etc].
The folders are in an unix server, so either java code or a shell script(bash/tcsh/etc) or their combination would do.
Try this:
File dir = new File("directoryName");
File temp;
String[] children = dir.list();
if (children !=null) {
for (int i=0; i<children.length; i++) {
temp = new File(children[i]);
if(temp.isDirectory()) //add children[i] to arrayList
}
}
The below Java code snippet should help you. It will return the list of all folders within a directory.It may return an empty list based on the manner in which you deal with any possible IO exception.
public List<String> getDirectoriesInFolder(String folderPath)
{
List<String> folderNames = new ArrayList<String>();
try
{
File directory = new File (folderPath);
String[] allFilesInFolder = directory.list();
for(String fileName : allFilesInFolder)
{
File f = new File(fileName);
if(f.isDirectory)
{
folderNames.add(fileName);
}
}
}
catch(IOException iex)
{
//Do any exception handling here...
}
return folderNames;
}
If you want to do it using Shell scripting then the guidance provided on the below links should help you come to a solution:
help with script to list directories
bash: put output from ls into an array
This would feel slightly cleaner to me than a blunt iteration constructing new File() each time.
public class DirFilter implements FileFilter {
public static FileFilter INSTANCE = new DirFilter();
#Override
public boolean accept(File file) {
return file.isDirectory();
}
}
File startDir = .....;
List<File> children = Arrays.asList(startDir.listFiles(DirFilter.INSTANCE));
I have around 500 text files inside a directory with each with the same prefix in their filename, for example: dailyReport_.
The latter part of the file is the date of the file. (For example dailyReport_08262011.txt, dailyReport_08232011.txt)
I want to delete these files using a Java procedure. (I could go for a shell script and add it a job in the crontab but the application is meant to used by laymen).
I can delete a single file using something like this:
try{
File f=new File("dailyReport_08232011.txt");
f.delete();
}
catch(Exception e){
System.out.println(e);
}
but can I delete the files having a certain prefix? (e.g. dailyReport08 for the 8th month) I could easily do that in shell script by using rm -rf dailyReport08*.txt .
But File f=new File("dailyReport_08*.txt"); doesnt work in Java (as expected).
Now is anything similar possible in Java without running a loop that searches the directory for files?
Can I achieve this using some special characters similar to * used in shell script?
No, you can't. Java is rather low-level language -- comparing with shell-script -- so things like this must be done more explicetly. You should search for files with required mask with folder.listFiles(FilenameFilter), and iterate through returned array deleting each entry. Like this:
final File folder = ...
final File[] files = folder.listFiles( new FilenameFilter() {
#Override
public boolean accept( final File dir,
final String name ) {
return name.matches( "dailyReport_08.*\\.txt" );
}
} );
for ( final File file : files ) {
if ( !file.delete() ) {
System.err.println( "Can't remove " + file.getAbsolutePath() );
}
}
You can use a loop
for (File f : directory.listFiles()) {
if (f.getName().startsWith("dailyReport_")) {
f.delete();
}
}
Java 8 :
final File downloadDirectory = new File("directoryPath");
final File[] files = downloadDirectory.listFiles( (dir,name) -> name.matches("dailyReport_.*?" ));
Arrays.asList(files).stream().forEach(File::delete)
With Java 8:
public static boolean deleteFilesForPathByPrefix(final String path, final String prefix) {
boolean success = true;
try (DirectoryStream<Path> newDirectoryStream = Files.newDirectoryStream(Paths.get(path), prefix + "*")) {
for (final Path newDirectoryStreamItem : newDirectoryStream) {
Files.delete(newDirectoryStreamItem);
}
} catch (final Exception e) {
success = false;
e.printStackTrace();
}
return success;
}
Simple version:
public static void deleteFilesForPathByPrefix(final Path path, final String prefix) {
try (DirectoryStream<Path> newDirectoryStream = Files.newDirectoryStream(path, prefix + "*")) {
for (final Path newDirectoryStreamItem : newDirectoryStream) {
Files.delete(newDirectoryStreamItem);
}
} catch (final Exception e) { // empty
}
}
Modify the Path/String argument as needed. You can even convert between File and Path. Path is preferred for Java >= 8.
I know I'm late to the party. However, for future reference, I wanted to contribute a java 8 stream solution that doesn't involve a loop.
It may not be pretty. I welcome suggestions to make it look better. However, it does the job:
Files.list(deleteDirectory).filter(p -> p.toString().contains("dailyReport_08")).forEach((p) -> {
try {
Files.deleteIfExists(p);
} catch (Exception e) {
e.printStackTrace();
}
});
Alternatively, you can use Files.walk which will traverse the directory depth-first. That is, if the files are buried in different directories.
Use FileFilter like so:
File dir = new File(<path to dir>);
File[] toBeDeleted = dir.listFiles(new FileFilter() {
boolean accept(File pathname) {
return (pathname.getName().startsWith("dailyReport_08") && pathname.getName().endsWith(".txt"));
}
for (File f : toBeDeleted) {
f.delete();
}
There isn't a wildcard but you can implement a FilenameFilter and check the path with a startsWith("dailyReport_"). Then calling File.listFiles(filter) gives you an array of Files that you can loop through and call delete() on.
I agree with BegemoT.
However, just one optimization:
If you need a simple FilenameFilter, there is a class in the Google packages.
So, in this case you do not even have to create your own anonymous class.
import com.google.common.io.PatternFilenameFilter;
final File folder = ...
final File[] files = folder.listFiles(new PatternFilenameFilter("dailyReport_08.*\\.txt"));
// loop through the files
for ( final File file : files ) {
if ( !file.delete() ) {
System.err.println( "Can't remove " + file.getAbsolutePath() );
}
}
Enjoy !
You can't do it without a loop. But you can enhance this loop. First of all, ask you a question: "what's the problem with searching and removing in the loop?" If it's too slow for some reason, you can just run your loop in a separate thread, so that it will not affect your user interface.
Other advice - put your daily reports in a separate folder and then you will be able to remove this folder with all content.
or in scala
new java.io.File(<<pathStr>>).listFiles.filter(_.getName.endsWith(".txt")).foreach(_.delete())
Have a look at Apache FileUtils which offers many handy file manipulations.