Java FileOutputStream Create File if not exists
It will throw a FileNotFoundException
if the file doesn't exist and cannot be created (doc), but it will create it if it can. To be sure you probably should first test that the file exists before you create the FileOutputStream
(and create with createNewFile()
if it doesn't):
File yourFile = new File("score.txt");
yourFile.createNewFile(); // if file already exists will do nothing
FileOutputStream oFile = new FileOutputStream(yourFile, false);
Java create file if does not exist
The problem is that
File f = new File(fName, "UTF8");
Doesn't set the file encoding to UTF8. Instead, the second argument is the child path, which has nothing to do with encoding; the first is the parent path.
So what you wanted is actually:
File f = new File("C:\\Parent", "testfile.txt");
or just:
File f = new File(fullFilePathName);
Without the second argument
Create a directory if it does not exist and then create the files in that directory as well
This code checks for the existence of the directory first and creates it if not, and creates the file afterwards. Please note that I couldn't verify some of your method calls as I don't have your complete code, so I'm assuming the calls to things like getTimeStamp()
and getClassName()
will work. You should also do something with the possible IOException
that can be thrown when using any of the java.io.*
classes - either your function that writes the files should throw this exception (and it be handled elsewhere), or you should do it in the method directly. Also, I assumed that id
is of type String
- I don't know as your code doesn't explicitly define it. If it is something else like an int
, you should probably cast it to a String
before using it in the fileName as I have done here.
Also, I replaced your append
calls with concat
or +
as I saw appropriate.
public void writeFile(String value){
String PATH = "/remote/dir/server/";
String directoryName = PATH.concat(this.getClassName());
String fileName = id + getTimeStamp() + ".txt";
File directory = new File(directoryName);
if (! directory.exists()){
directory.mkdir();
// If you require it to make the entire directory path including parents,
// use directory.mkdirs(); here instead.
}
File file = new File(directoryName + "/" + fileName);
try{
FileWriter fw = new FileWriter(file.getAbsoluteFile());
BufferedWriter bw = new BufferedWriter(fw);
bw.write(value);
bw.close();
}
catch (IOException e){
e.printStackTrace();
System.exit(-1);
}
}
You should probably not use bare path names like this if you want to run the code on Microsoft Windows - I'm not sure what it will do with the /
in the filenames. For full portability, you should probably use something like File.separator to construct your paths.
Edit: According to a comment by JosefScript below, it's not necessary to test for directory existence. The directory.mkdir()
call will return true
if it created a directory, and false
if it didn't, including the case when the directory already existed.
FileoutputStream FileNotFoundException
It will throw a FileNotFoundException if the file doesn't exist and cannot be created (doc), but it will create it if it can. To be sure you probably should first test that the file exists before you create the FileOutputStream (and create with createNewFile() if it doesn't)
File yourFile = new File("score.txt");
yourFile.createNewFile();
FileOutputStream oFile = new FileOutputStream(yourFile, false);
Answer from here: Java FileOutputStream Create File if not exists
Create intermediate folders if one doesn't exist
You have to actually call some method to create the directories. Just creating a file
object will not create the corresponding file or directory on the file system.
You can use File#mkdirs()
method to create the directory: -
theFile.mkdirs();
Difference between File#mkdir()
and File#mkdirs()
is that, the later will create any intermediate directory if it does not exist.
how to create a file in Java only if one doesn't already exist?
File.createNewFile()
only creates a file if one doesn't already exist.
EDIT: Based on your new description of wanting to lock the file after it's created you can use the java.nio.channels.FileLock
object to lock the file. There isn't a one line create and lock though like you are hoping. Also, see this SO question.
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