Why does this Java code not write to file?

There are so many Input/Output Classes in Java.
It is really a mess. You do not know which to use.
Which functions does operating system offer ? There will be one
to read one byte of a file or many bytes of a file I guess.

So for example if I use this.

String path = "C:\\Users\\myName\\test.txt";
FileOutputStream fos = new FileOutputStream(path);
fos.write(333);

If I open it with a text editor it shows me letter "G" . Already I do not understand this.

And this code does not write anything, the file is empty weirdly.

String path = "C:\\Users\\myName\\test.txt";
FileOutputStream fos = new FileOutputStream(path);
BufferedWriter out = new BufferedWriter(new OutputStreamWriter(fos));
out.write("something");

All these I/O classes just confuse me. What does buffered mean. It reads 1000 Bytes at once. So
there is operating function to straight away read 1000 Bytes of a file I guess.

> There are so many Input/Output Classes in Java. It is really a mess. You do not know which to use.

The Files class is by far the easiest to use. For instance,

Files.writeString(Paths.get("test.txt"), "hello world!");

creates a text file named "test.txt" containing the text "hello world!".

The other classes are only needed if you want to do something fancy (for instance, deal with files too big to fit in main memory). For instance, suppose you wanted to read a huge log file (hundreds of gigabytes long) and wanted to write each line containing a particular word to another file. If you were to open the file with

Files.readAllLines(Paths.get("huge.log"));

you'd receive an OutOfMemoryError because the file doesn't fit in main memory. To work around that, we must read the file piece-wise, and that is what all those Reader and Writer classes (or InputStream and OutputStream, if you're dealing with binary files) are good for:

	try (
		var reader = Files.newBufferedReader(Paths.get("huge.log"));
		var writer = Files.newBufferedWriter(Paths.get("interesting.log"));
	) {
		String line;
		while ((line = reader.readLine()) != null) {
			if (line.contains(searchWord)) {
				writer.write(line);
				writer.write('\n');
			}
		}
	}

As you can see, their use is quite a bit more complicated. For one, we must close the Reader and Writer once we are done with them, which is easiest accomplished with the try with resources statement shown above.

Closing is necessary because most operating systems limit the number of files that can be open at once. Closing also gives any Buffered* classes the opportunity to empty their buffers, ensuring that any data still in buffers is passed on to the file system.

If we fail to close, as you did in your example code, the file remains open until our program exits, upon which time any data in the buffers is lost, resulting in the incomplete file you found.

You need to close the instances of BufferedWriter out and FileOutputStream fos, after invoking the out.write("something"), then only the file gets created successfully with the contents you are trying to write.

	 public static void main(String[] args) throws IOException {
		 String path = "C:\\Users\\myName\\test.txt";
		 FileOutputStream fos = new FileOutputStream(path);
		 BufferedWriter out = new BufferedWriter(new OutputStreamWriter(fos));
		 out.write("something");
		 out.close(); // Closes the stream, flushing it first. 
		 fos.close(); // Closes this file output stream and releases any system resources associated with this stream.
	    }

Closing the instances of BufferedWriter and FileOutputStream will solve the issue.
fos.write(333) => The number has been written to the file and when you open the file it opens in ASCII format. You can use below code.

    public static void main(String[] args) throws IOException {

        FileWriter fw=new FileWriter("D:\\test.txt");
        fw.write("Hello! This is a sample text");
        System.out.println("Writing successful");
        fw.close();

        /* your code
        String path = "D:\\test1.txt";
        FileOutputStream fos = new FileOutputStream(path);
        BufferedWriter out = new BufferedWriter(new OutputStreamWriter(fos));
        out.write("Hello! This is a sample text");
        out.close(); 
        fos.close();
        */
    }