How many subclasses of the Writer class are there in Java?

There are 7 subclasses of the Writer class in Java. These are:

1. OutputStreamWrite for writing a character stream
2. BufferedWriter for buffering other writers
3. PrintWriter for writing formatted data
4. PipedWriter for writing to a pipe
5. CharArrayWriter for writing to a char array
6. StringWriter for writing to a string
7. FilterWriter for writing filtered streams. So, this is the correct answer.