How to Write the output into txt file using FileWriter - java

This is my java code to find the locations of files inside the directory and write them into a txt file as the output ,but after compilation the contents are not writing into txt file. please give me some solution.
public void listFilesAndFilesSubDirectories(String directoryName)
{
File directory = new File(directoryName);
List<String> list=new ArrayList<String> ();
//get all the files from a directory
if(directory.exists()){
File[] fList = directory.listFiles();
for (File file : fList){
if (file.isFile()){
if(file.getName().endsWith(".c")==true || file.getName().endsWith(".h")==true){
// System.out.println(file.getAbsolutePath());
list.add(file.getAbsolutePath());
}
} else if (file.isDirectory()){
listFilesAndFilesSubDirectories(file.getAbsolutePath());
}
else break;
}
try{
FileWriter fw=new FileWriter("C:/Users/Public/afreen/module.txt");
BufferedWriter out = new BufferedWriter(fw);
for(String str: list)
{
System.out.println(str);
out.write(str);
}
out.flush();
out.close();
}
catch(Exception e)
{
System.out.println(e);
}
System.out.println("Success....");
}
else
{
System.out.println("The directory is not exist , please enter a valid path");
}
}
The above code will take the input as the path for directory and finds the location of files which I want.But the locations are not able to write into txt file,I am not abel to find the actual reason ,please help me out to find the solution of it.


Each time your method gets called (recursively) creates a new list and add the directory name to it but that list is not the one you are printing from, try to use a shared resource. for example use a global variable or etc.

Related

Java I/O Opening Files in External Program

I have a Java program that I am using to scan a directory to look for certain files. It finds the files but now I am trying to get the code to open the files once it finds them, but I am not sure how to do that.
Here a part of my code
File file = new File("/Users/******/Desktop/******");
String[] A = file.list();
File[] C = file.listFiles();
for (String string : A) {
if (string.endsWith(".txt")) {
System.out.println(string);
}
if (string.contains("******")) {
System.out.println("It contains X file");
}
}
I am trying to get it so once it finds the files ending in .txt, it opens all of them
I have tried using Google on how to solve his, I came across .getRuntime() and so I tried
try{
Runtime.getRuntime().exec("******.txt");
} catch(IOException e){
}
But I am not fully understanding how how this works. I am trying to get to so that once it finds the files it opens them. I am not trying to have the IDE open the text on the screen. I want the actual Notepad/TextEdit program to open.

File[] files = new File("/Users/******/Desktop/******").listFiles();
for (File f : files) {
String fileName = f.getName();
if (fileName.endsWith(".txt")) {
System.out.println(fileName);
}
if (fileName.contains("******")) {
System.out.println("It contains X file");
}
}

Java - Read many txt files on a folder and process them

I followed this question:
Now in my case i have 720 files named in this way: "dom 24 mar 2013_00.50.35_128.txt", every file has a different date and time. In testing phase i used Scanner, with a specific txt file, to do some operations on it:
Scanner s = new Scanner(new File("stuff.txt"));
My question is:
How can i reuse scanner and read all 720 files without having to set the precise name on scanner?
Thanks

Assuming you have all the files in one place:
File dir = new File("path/to/files/");
for (File file : dir.listFiles()) {
Scanner s = new Scanner(file);
...
s.close();
}
Note that if you have any files that you don't want to include, you can give listFiles() a FileFilter argument to filter them out.

Yes, create your file object by pointing it to a directory and then list the files of that directory.
File dir = new File("Dir/ToYour/Files");
if(dir.isDir()) {
for(File file : dir.listFiles()) {
if(file.isFile()) {
//do stuff on a file
}
}
} else {
//do stuff on a file
}

You can try this in this way
File folder = new File("D:\\DestFile");
File[] listOfFiles = folder.listFiles();
for (File file : listOfFiles) {
if (file.isFile()&&(file.getName().substring(file.getName().lastIndexOf('.')+1).equals("txt"))) {
// Scanner
}
}

File file = new File(folderNameFromWhereToRead);
if(file!=null && file.exists()){
File[] listOfFiles = file.listFiles();
if(listOfFiles!=null){
for (int i = 0; i < listOfFiles.length; i++) {
if (listOfFiles[i].isFile()) {
// DO work
}
}
}
}

How to get all the filenames in android directory?

Im trying to list all the files in a particular folder of my android emulator and i keep getting null answer.
Heres my code:
File sdCardRoot = Environment.getExternalStorageDirectory();
File[] file= new File(sdCardRoot+"path");
for (File f : file.listFiles()) {
if (f.isFile())
String name = f.getName();
}
This doesnt seem to work dont know why.

I've split the function in two parts, first function gets all the files in the given path and the second function gets the filenames from the file array.
public File[] GetFiles(String DirectoryPath) {
File f = new File(DirectoryPath);
f.mkdirs();
File[] file = f.listFiles();
return file;
}
public ArrayList<String> getFileNames(File[] file){
ArrayList<String> arrayFiles = new ArrayList<String>();
if (file.length == 0)
return null;
else {
for (int i=0; i<file.length; i++)
arrayFiles.add(file[i].getName());
}
return arrayFiles;
}

change
File[] file= new File(sdCardRoot+"path");
with
File[] file= new File(sdCardRoot, "path");
and make sure the directory path exits

Just Check this:
List<File> files = getListFiles(new File("YOUR ROOT"));
private List<File> getListFiles(File parentDir) {
ArrayList<File> inFiles = new ArrayList<File>();
File[] files = parentDir.listFiles();
for (File file : files) {
if (file.isDirectory()) {
inFiles.addAll(getListFiles(file));
} else {
if(file.getName().endsWith(".csv")) {
inFiles.add(file);
}
}
}
return inFiles;

Since sdCardRoot is instance of File, sdCardRoot+"path" will return the same thing as sdCardRoot.toString() + "path".
However, calling file.toString() returns file name, but not absolute path. You need to call sdCardRoot.getAbsolutePath() + "path".
Also, make sure that you have allowed the emulator to use a certain amount of memory for external storage.

Moving file to new location then deleting the Previous file

I want to move file from one path to another path but instead of moving it copy the file to new location.
Kindly provide any hints
Thanks in advance
MovePngToPreviewDir pngToPreviewDir = new MovePngToPreviewDir(null, "png");
File[] listOfPNGFiles = RootDir.listFiles(pngToPreviewDir);
for(File file:listOfPNGFiles){
Log.e("PNG = ",file.getAbsolutePath());
Log.e("PNG = ",file.getName());
if(previewDiagramDir == null){
Log.e("Preview Diagram Dir is NULL","Preview Diagram DIR is NULL");
}
if(file!= null && previewDiagramDir != null){
Log.e("Preview Diagram Dir",previewDiagramDir.getAbsolutePath()+"/");
if(file.renameTo(new File(previewDiagramDir, file.getName()))){
Log.e("PNG File is successfully Moved",file.getName());
}else{
Log.e("Error in Moving PNG File","Error in Moving PNG file");
}
}else{
}

If you want to copy the file to another location, you can use file.renameTo() method of File class, related to your istance object file, trying this:
file.renameTo(new File("new_directory_to_copy_file"+file.getName()));
After copying the file, you can delete it with file.delete();.
Note: The method delete() returns a boolean object, then you can check the correct file deletion with:
boolean del = file.delete();
if(del) System.out.println("File "+file.getName()+" deleted!");
else System.out.println("File "+file.getName()+"not deleted!");
About the File class API: http://download.oracle.com/javase/6/docs/api/java/io/File.html

Use file.delete() after the file is copied to another location so that it is completely moved to the new location.

I have moved files to the destination directory and after moving deleted those moved files from source folder, in three ways, and at last am using the 3rd approach in my project.
1st approach:
File folder = new File("SourceDirectory_Path");
File[] listOfFiles = folder.listFiles();
for (int i = 0; i < listOfFiles.length; i++) {
Files.move(Paths.get("SourceDirectory_Path"+listOfFiles[i].getName()), Paths.get("DestinationDerectory_Path"+listOfFiles[i].getName()));
}
System.out.println("SUCCESS");
2nd approach:
Path sourceDir = Paths.get("SourceDirectory_Path");
Path destinationDir = Paths.get("DestinationDerectory_Path");
try(DirectoryStream<Path> directoryStream = Files.newDirectoryStream(sourceDir)){
for (Path path : directoryStream) {
File d1 = sourceDir.resolve(path.getFileName()).toFile();
File d2 = destinationDir.resolve(path.getFileName()).toFile();
File oldFile = path.toFile();
if(oldFile.renameTo(d2)){
System.out.println("Moved");
}else{
System.out.println("Not Moved");
}
}
}catch (Exception e) {
e.printStackTrace();
}
3rd approach:
Path sourceDirectory= Paths.get(SOURCE_FILE_PATH);
Path destinationDirectory = Paths.get(SOURCE_FILE_MOVE_PATH);
try (DirectoryStream<Path> directoryStream = Files.newDirectoryStream(sourceDirectory)) {
for (Path path : directoryStream) {
Path dpath = destinationDirectory .resolve(path.getFileName());
Files.move(path, dpath, StandardCopyOption.REPLACE_EXISTING);
}
} catch (IOException ex) {
ex.printStackTrace();
}

Rename a file using Java

Can we rename a file say test.txt to test1.txt ?
If test1.txt exists will it rename ?
How do I rename it to the already existing test1.txt file so the new contents of test.txt are added to it for later use?

Copied from http://exampledepot.8waytrips.com/egs/java.io/RenameFile.html
// File (or directory) with old name
File file = new File("oldname");
// File (or directory) with new name
File file2 = new File("newname");
if (file2.exists())
throw new java.io.IOException("file exists");
// Rename file (or directory)
boolean success = file.renameTo(file2);
if (!success) {
// File was not successfully renamed
}
To append to the new file:
java.io.FileWriter out= new java.io.FileWriter(file2, true /*append=yes*/);

In short:
Files.move(source, source.resolveSibling("newname"));
More detail:
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardCopyOption;
The following is copied directly from http://docs.oracle.com/javase/7/docs/api/index.html:
Suppose we want to rename a file to "newname", keeping the file in the same directory:
Path source = Paths.get("path/here");
Files.move(source, source.resolveSibling("newname"));
Alternatively, suppose we want to move a file to new directory, keeping the same file name, and replacing any existing file of that name in the directory:
Path source = Paths.get("from/path");
Path newdir = Paths.get("to/path");
Files.move(source, newdir.resolve(source.getFileName()), StandardCopyOption.REPLACE_EXISTING);

You want to utilize the renameTo method on a File object.
First, create a File object to represent the destination. Check to see if that file exists. If it doesn't exist, create a new File object for the file to be moved. call the renameTo method on the file to be moved, and check the returned value from renameTo to see if the call was successful.
If you want to append the contents of one file to another, there are a number of writers available. Based on the extension, it sounds like it's plain text, so I would look at the FileWriter.

For Java 1.6 and lower, I believe the safest and cleanest API for this is Guava's Files.move.
Example:
File newFile = new File(oldFile.getParent(), "new-file-name.txt");
Files.move(oldFile.toPath(), newFile.toPath());
The first line makes sure that the location of the new file is the same directory, i.e. the parent directory of the old file.
EDIT:
I wrote this before I started using Java 7, which introduced a very similar approach. So if you're using Java 7+, you should see and upvote kr37's answer.

Renaming the file by moving it to a new name. (FileUtils is from Apache Commons IO lib)
String newFilePath = oldFile.getAbsolutePath().replace(oldFile.getName(), "") + newName;
File newFile = new File(newFilePath);
try {
FileUtils.moveFile(oldFile, newFile);
} catch (IOException e) {
e.printStackTrace();
}

This is an easy way to rename a file:
File oldfile =new File("test.txt");
File newfile =new File("test1.txt");
if(oldfile.renameTo(newfile)){
System.out.println("File renamed");
}else{
System.out.println("Sorry! the file can't be renamed");
}

import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import static java.nio.file.StandardCopyOption.*;
Path yourFile = Paths.get("path_to_your_file\text.txt");
Files.move(yourFile, yourFile.resolveSibling("text1.txt"));
To replace an existing file with the name "text1.txt":
Files.move(yourFile, yourFile.resolveSibling("text1.txt"),REPLACE_EXISTING);

Try This
File file=new File("Your File");
boolean renameResult = file.renameTo(new File("New Name"));
// todo: check renameResult
Note :
We should always check the renameTo return value to make sure rename file is successful because it’s platform dependent(different Operating system, different file system) and it doesn’t throw IO exception if rename fails.

Yes, you can use File.renameTo(). But remember to have the correct path while renaming it to a new file.
import java.util.Arrays;
import java.util.List;
public class FileRenameUtility {
public static void main(String[] a) {
System.out.println("FileRenameUtility");
FileRenameUtility renameUtility = new FileRenameUtility();
renameUtility.fileRename("c:/Temp");
}
private void fileRename(String folder){
File file = new File(folder);
System.out.println("Reading this "+file.toString());
if(file.isDirectory()){
File[] files = file.listFiles();
List<File> filelist = Arrays.asList(files);
filelist.forEach(f->{
if(!f.isDirectory() && f.getName().startsWith("Old")){
System.out.println(f.getAbsolutePath());
String newName = f.getAbsolutePath().replace("Old","New");
boolean isRenamed = f.renameTo(new File(newName));
if(isRenamed)
System.out.println(String.format("Renamed this file %s to %s",f.getName(),newName));
else
System.out.println(String.format("%s file is not renamed to %s",f.getName(),newName));
}
});
}
}
}

If it's just renaming the file, you can use File.renameTo().
In the case where you want to append the contents of the second file to the first, take a look at FileOutputStream with the append constructor option or The same thing for FileWriter. You'll need to read the contents of the file to append and write them out using the output stream/writer.

As far as I know, renaming a file will not append its contents to that of an existing file with the target name.
About renaming a file in Java, see the documentation for the renameTo() method in class File.

Files.move(file.toPath(), fileNew.toPath());
works, but only when you close (or autoclose) ALL used resources (InputStream, FileOutputStream etc.) I think the same situation with file.renameTo or FileUtils.moveFile.

Here is my code to rename multiple files in a folder successfully:
public static void renameAllFilesInFolder(String folderPath, String newName, String extension) {
if(newName == null || newName.equals("")) {
System.out.println("New name cannot be null or empty");
return;
}
if(extension == null || extension.equals("")) {
System.out.println("Extension cannot be null or empty");
return;
}
File dir = new File(folderPath);
int i = 1;
if (dir.isDirectory()) { // make sure it's a directory
for (final File f : dir.listFiles()) {
try {
File newfile = new File(folderPath + "\\" + newName + "_" + i + "." + extension);
if(f.renameTo(newfile)){
System.out.println("Rename succesful: " + newName + "_" + i + "." + extension);
} else {
System.out.println("Rename failed");
}
i++;
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
and run it for an example:
renameAllFilesInFolder("E:\\Downloads\\Foldername", "my_avatar", "gif");

I do not like java.io.File.renameTo(...) because sometimes it does not renames the file and you do not know why! It just returns true of false. It does not thrown an exception if it fails.
On the other hand, java.nio.file.Files.move(...) is more useful as it throws an exception when it fails.

Running code is here.
private static void renameFile(File fileName) {
FileOutputStream fileOutputStream =null;
BufferedReader br = null;
FileReader fr = null;
String newFileName = "yourNewFileName"
try {
fileOutputStream = new FileOutputStream(newFileName);
fr = new FileReader(fileName);
br = new BufferedReader(fr);
String sCurrentLine;
while ((sCurrentLine = br.readLine()) != null) {
fileOutputStream.write(("\n"+sCurrentLine).getBytes());
}
fileOutputStream.flush();
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
fileOutputStream.close();
if (br != null)
br.close();
if (fr != null)
fr.close();
} catch (IOException ex) {
ex.printStackTrace();
}
}
}

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