Error where FileOutputStream only writes to file after the program has been terminated

I've had this error in the past but never fully understood it. After closing an OutputStream, regardless of the location of the java file or the manner in which it is called, completely screws up all sequential runs or attempts to write to another file, even if a different method of writing to a file is used. For this reason I avoid closing streams even though it is a horrible habit not to. In my program, I created was trying a test case that had a close statement which destroyed all of my previous streams, making it for some reason that they only write to files after the program has been terminated.

I kept the file location open and it writes the Text in the text file at the appropriate time, however the "Preview" panel in Windows does not detect it (which used to happen). Note that this all worked perfectly before the stream was accidentally closed. Is there a manner to reset the stream? I've tried flushing it during the process but is still does not run as it did prior.

Here is the method used to create the file:

protected void createFile(String fileName, String content) {
    try {
        String fileLoc = PATH + fileName + ".txt";
        File f = new File(fileLoc);
        if(!f.isFile())
            f.createNewFile();
        FileOutputStream outputStream = new FileOutputStream(fileLoc);
            byte[] strToBytes = content.getBytes();
            outputStream.write(strToBytes);
    } catch (IOException e) {
        e.printStackTrace();
        return;
    }
}

as well as the method used to read the file:

protected String readFile(String fileName) {
    try {
        StringBuilder sb = new StringBuilder("");
        String fileLoc = PATH + fileName + ".txt";
        File f = new File(fileLoc);
        if(!f.exists())
            return "null";
        Scanner s = new Scanner(f);
        int c = 0;
        while(s.hasNext()) {
            String str = s.nextLine();
            sb.append(str);
            if(s.hasNext())
                sb.append("\n");
        }
        return sb.toString();
    } catch(Exception e) {
        e.printStackTrace();
        return "null";
    }
}

I'd be happy to answer any clarification questions if needed. Thank you for the assistance.

Solution

You need to call flush() on the stream to write the bytes to the stream.

You're currently calling write() by itself, like this:

FileOutputStream outputStream = new FileOutputStream(fileLoc);
outputStream.write(content.getBytes());

What you want to do is this:

FileOutputStream outputStream = new FileOutputStream(fileLoc);
outputStream.write(content.getBytes());
outputStream.flush();

From the Javadoc (https://docs.oracle.com/javase/8/docs/api/java/io/OutputStream.html#flush--) for OutputStream (where FileOutputStream is an OutputStream), this is what it says for flush():

Flushes this output stream and forces any buffered output bytes to be written out. The general contract of flush is that calling it is an indication that, if any bytes previously written have been buffered by the implementation of the output stream, such bytes should immediately be written to their intended destination.

Even better would be to close the stream in a finally block, so that no matter what your code always tries to free up any open resources, like this:

FileOutputStream outputStream = null;
try {
    outputStream = new FileOutputStream(fileLoc);
    outputStream.write(content.getBytes());
    outputStream.flush();
} finally {
    if (outputStream != null) {
        outputStream.close();
    }
}

or use automatic resource management, like this:

try (FileOutputStream outputStream = new FileOutputStream(fileLoc)) {
    outputStream.write(content.getBytes());
    outputStream.flush();
}