Java FileReader is a class that reads characters from a file in the file system. It is a subclass of the InputStreamReader class, which is a bridge between byte streams and character streams.

Here's an example of how to use FileReader to read a file:

try (FileReader reader = new FileReader("example.txt")) {
    int c;
    while ((c = reader.read()) != -1) {
        System.out.print((char) c);
    }
} catch (IOException e) {
    e.printStackTrace();
}

In this example, we create a new FileReader object and pass the name of the file we want to read ("example.txt") as a parameter. We then read the file one character at a time using the read() method, which returns the next character in the file as an integer. We cast this integer to a character and print it to the console. We continue reading characters until the end of the file is reached (which is indicated by the read() method returning -1).

Note that we use a try-with-resources statement to automatically close the FileReader when we're done with it, and we catch any IOException that might occur during the read operation.