Here is an example of how you might use the ReadAheadInputStream class from the org.apache.commons.io package in Java:

import java.io.ByteArrayInputStream;
import java.io.InputStream;
import org.apache.commons.io.input.ReadAheadInputStream;

public class MyClass {

    public void doSomethingWithReadAheadInputStream() throws Exception {
        // Create a byte array input stream
        byte[] data = new byte[] {1, 2, 3, 4, 5};
        InputStream inputStream = new ByteArrayInputStream(data);
        
        // Create a read-ahead input stream
        ReadAheadInputStream readAheadInputStream = new ReadAheadInputStream(inputStream);

        // Read data from the read-ahead input stream
        int value = readAheadInputStream.read();
        while (value != -1) {
            System.out.println(value);
            value = readAheadInputStream.read();
        }
    }
}

The ReadAheadInputStream class is a wrapper for an existing InputStream that reads ahead by a certain number of bytes in order to improve performance. In this example, we create a ByteArrayInputStream and pass it to the ReadAheadInputStream constructor and read data from it.

The ReadAheadInputStream class also provides a mark(int readlimit) and reset() method, which allows you to mark a position in the stream and return to it later.

By default, ReadAheadInputStream class will read ahead 512 bytes, but you can configure this by passing a different value to the constructor.