Creating a directory if it doesn't exist and then writing a file

[Jack Tauson]

@Override
	public void sendMessage(String msg) throws DaoException {
		
		 String[] parts = msg.split("#");
		 String requestID = parts[0].trim();
		 String userName = parts[1].trim();
		 String applicationName = parts[2].trim();
		
		logger.info("Request ID "+requestID);
		logger.info("User Name "+userName);
		logger.info("Application Name "+applicationName);
		
		
		
		 try {
	    	   
	    	   
			     FileWriter fw = new FileWriter("/srv/file_users/JACK/employee_status_downloader_"+unixTimestamp+".csv");

			     CSVWriter writer = new CSVWriter(fw);
			   
			     writer.writeAll(rsDemo,true);
			     writer.close();  
			     fw.close();
			    
			    
			  }
			catch(Throwable th) {
				throw new DaoException(th.getMessage(), th);
		    }
			finally {
				
				
			}	
		
		
		
	}
	long unixTimestamp = Instant.now().getEpochSecond();

As you can see, right now, I am writing a file named employee_status_downloader_unixtimestamp.csv in an already created directory on RHEL server as shown in this line of code below:

FileWriter fw = new FileWriter("/srv/file_users/JACK/employee_status_downloader_"+unixTimestamp+".csv");

So, I manually created a folder named JACK and then specified the above path so that the files related to the userName JACK are inside JACK folder.

Since the userName can be different and I am already getting the userName in my method above from this line of code String userName = parts[1].trim();, I am wondering if I could make use of this
to create a directory based on the userName?

So, I am not using System.getProperty("user.name"); here since I am already getting userName in my method above.

After looking online , I found that people are suggesting to do something like this :

File fl = new File("/path/directory").mkdirs(); where directory is the name of the directory I want to create/exist. But since I am using FileWriter above,  I am wondering how should I go about using both so that
I could also create a directory if it doesn't exist and then write a file in the directory.

References:

Bozho's answer:

https://stackoverflow.com/questions/3634853/how-to-create-a-directory-in-java

[Tony Docherty]

If you create a File object for the directory you want to create you can use the isDirectory() and exists() methods to determine if a directory (or file) with that name already exists and if it doesn't use the mkDir() or mkDirs() method to create the directory. I suggest you read the Java docs for these methods to see the difference between them.

[Rob Spoor]

Both mkdir and mkdirs returns false if the directory already exists, so it's not necessary to check for existence first. I tend to use mkdirs because it will create all intermediate directories as well. When using java.nio.file.Files I also tend to use createDirectories; an added bonus is that it doesn't throw an exception if the directory already exists, unlike createDirectory.

[Tony Docherty]

Apologies if I'm being pedantic here but mkdir and mkdirs returning false means they couldn't create the directory not that the directory already exists. A return value of false probably is because the directory already exists but it could be for other reasons, such as the user doesn't have permission to create directories or the file system is unable to create directories.

[Stephan van Hulst]

Agree with Rob, the easiest way to do this is with Files.createDirectories(). You can also easily use it with Paths.get() to compose your file path:

var directoryPath = Paths.get("srv", "file_users", userName");
Files.createDirectories(directoryPath);

var filePath = directoryPath.resolve(String.format("employee_status_downloader_%s.csv", unixTimestamp));

using (var writer = Files.newBufferedWriter(filePath, CREATE_NEW, WRITE)) {
  //
}

[Rob Spoor]

Tony Docherty wrote:Apologies if I'm being pedantic here but mkdir and mkdirs returning false means they couldn't create the directory not that the directory already exists. A return value of false probably is because the directory already exists but it could be for other reasons, such as the user doesn't have permission to create directories or the file system is unable to create directories.

True, that's why I prefer to use Path instead of File. It throws proper IOExceptions if things go wrong.

@Stephan: working in C# lately? In Java we use "try" instead of "using"

[Stephan van Hulst]

I seem to be mixing up my languages a lot lately.