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After creating file using java, there were no values in it

I have created file using java, with following code
String Filecontent= "hei";
creating file
PrintWriter writer=new PrintWriter("D://balanworkspace//Coretest//Corejavatest//src//intvquestest//mydet3_8.txt","UTF-8");
printing the string
System.out.println(Filecontent);
writing to file
writer.println(Filecontent);
when I opened the file, there is no values. Why is it so?

You need to close the PrintWriter by doing this:
writer.close();

Make sure that the complete path of your file exists... If not, create a File and use mkdirs method to create it. After that, write with your PrintWriter
File f = null;
f = new File("yourpath");
Boolean bool = f.mkdirs();

You will need to flush the stream, for the values to appear in the file.
writer.flush()
Closing the stream will invoke the same,
writer.close()
If you don't want to use flush and close, you could pass in an argument "true" to the constructor of PrintWriter which will cause the output to be flushed each time println() is invoked.
PrintWriter(Writer out, boolean autoFlush)

Write String to text-file in java [duplicate]

This question already has answers here:
How do I save a String to a text file using Java?
(24 answers)
Closed 7 years ago.
Wanna save some information that I parse from a JSON to a plain text into a file and I also want this information to not be overwritten every time you run the program. It's suppose to work as a simple error logging system.
So far have I tried this:
FileWriter fileWriter = null;
File file = new File("/home/anderssinho/bitbucket/dblp-article-analyzer/logg.txt");
// if file doesn't exists, then create it
if (!file.exists()) {
file.createNewFile();
}
...
String content = "------------------------------------";
fileWriter = new FileWriter(file);
fileWriter.write(content);
//fileWriter.write(obj.getString("title"));
//fileWriter.write(obj.getString("creators"));
//fileWriter.write(article.GetElectronicEdition());
But when I do this it seems that I overwrite the information all the time and I'm also having problem to save the information I wanna grab from the JSON-array that I've got.
How can I do to make this work?

FileWriter fooWriter = new FileWriter(myFoo, false);
// true to append
// false to overwrite;
where myFoo is the File name
See this link

use append:
PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter("logg.txt", true)));
see this:
How to append text to an existing file in Java

Can you be more elaborate on this? If the problem is just not able to append then you can just add an argument to the FileWriter saying it to append and not write from the beginning.
Check the constructor here:
public FileWriter(String fileName, boolean append) throws IOException
Official Java Documentation:
Constructs a FileWriter object given a file name with a boolean indicating whether or not to append the data written.
Parameters:
fileName - String The system-dependent filename.
append - boolean if true, then data will be written to the end of the file rather than the beginning.
Throws:
IOException - if the named file exists but is a directory rather than a regular file, does not exist but cannot be created, or cannot be opened for any other reason

How can I deleting the content of a file without deleting it self?

I want to clear the content of a file witch have a specific extension file.tctl, i don't want to change any thing about the file neither deleting it. The file is generated from a specific model checker so that i have just to delete the content and write my own. I tried to print an empty string like that:
PrintWriter writer = new PrintWriter(file.tctl);
writer.print("");
writer.close();
but the file doesn't work any more. So if there's another method to clear the content of the file.

Just remove the print altogether from your code. You've already truncated the file with the new FileOutputStream/PrintWriter/ whatever you use to open it. No I/O or truncate() necessary. Don't use append mode.

Most easy way I guess
new RandomAccessFile("filename.ext", "rw").setLength(0);

Call your write() method like this:
.write((new String()).getBytes());
This will make your file empty. If that doesn't works, try with this:
FileOutputStream erasor = new FileOutputStream("filename.ext");
erasor.write((new String()).toByteArray());
erasor.close();
Or just try to overwrite the file
//open file in override mode
FileOutputStream out = new FileOutputStream("filename.ext");
//now anything that we write here will remove the old one so just write space ("") here

You have to use a FileOutputStream and then you have the truncate() method:
File f = new File("path-of-the-file.here");
FileChannel channel = new FileOutputStream(f, true).getChannel();
channel.truncate(0);
channel.close();

How to update files without losing previously written info?

I use scanner & PrintWriter for files in JAVA. When i create a file & write some info in it & close it, next time i open the file & write something in it the previous info gets overwritten(previous info gets deleted). I need that information. Tell me a way so that i can write the info in file without overwriting(deleting)previous information.

You have to use :
new PrintWriter(new FileWriter(file , true));
Read the documentation of FileWriter(File file,boolean append)
Constructs a FileWriter object given a File object. If the second argument is true, then bytes will be written to the end of the file rather than the beginning.
Parameters:
file - a File object to write to
append - if true, then bytes will be written to the end of the file rather than the beginning
FileWriter implements the Appendable interface.The second parameter to the FileWriter constructor will tell it to append to the file. It is responsible for being able to add some content to the end of particular file/stream.

Initialize your PrintWriter like this to append to the file
PrintWriter pw = new PrintWriter(new FileWriter(file, true));
Last param of the FileWriter is the append flag.

How to write more than once to text file using PrintWriter

I know how to create a PrintWriter and am able to take strings from my gui and print it to a text file.
I want to be able to take the same program and print to the file adding text to the file instead of replacing everything already in the text file. How would I make it so that when more data is added to the text file, it is printed on a new line every time?
Any examples or resources would be awesome.

try
{
PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter("outfilename", true)));
out.println("the text");
out.close();
} catch (IOException e) {
}
The second parameter to the FileWriter constructor will tell it to append to the file (as opposed to clearing the file).
Using a BufferedWriter is recommended for an expensive writer (i.e. a FileWriter), and using a PrintWriter gives you access to println syntax that you're probably used to from System.out.
But the BufferedWriter and PrintWriter wrappers are not strictly necessary.

PrintWriter writer=new PrintWriter(new FileWriter(new File("filename"),true));
writer.println("abc");
FileWriter constructor comes with append attribute,if it is true you can append to a file.
check this

Your PrintWriter wraps another writer, which is probably a FileWriter. When you construct that FileWriter, use the constructor that takes both a File object and an "append" flag. If you pass true as the append flag, it'll open the file in append mode, which means that new output will go at the end of the file's existing contents, rather than replacing the existing contents.