ByteArrayInputStream is a class in Java that is used to read data from an array of bytes as an input stream. It is a subclass of InputStream, which is an abstract class that provides a standard way of reading data from different sources in the form of bytes.

Here's an example of using the ByteArrayInputStream class to read data from a byte array:

import java.io.*;

public class ByteArrayInputStreamExample {
    public static void main(String[] args) {
        try {
            byte[] data = {72, 101, 108, 108, 111, 44, 32, 119, 111, 114, 108, 100, 33};
            ByteArrayInputStream input = new ByteArrayInputStream(data);
            int character;
            while ((character = input.read()) != -1) {
                System.out.print((char) character);
            }
            input.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

In this example, we create a byte array data containing some text in ASCII format. We then create a ByteArrayInputStream object and pass the data array as a parameter. We read the data from the input stream using the read method of the ByteArrayInputStream object and cast each byte to a character using the (char) operator. Finally, we close the input stream using the close method.

The ByteArrayInputStream class provides several other methods for reading data from an array of bytes, including read(byte[] b, int off, int len), which reads up to len bytes of data from the input stream into the byte array b, starting at the specified offset off, and skip(long n), which skips over and discards n bytes of data from the input stream.

Overall, the ByteArrayInputStream class provides a flexible and efficient way of reading data from a byte array in Java. By using the various methods provided by ByteArrayInputStream, you can read data from byte arrays in a variety of different ways depending on your specific needs.