public class InputStreamExample1 {

  static final int SIZE = 1024 * 1024 * 256;
  static final byte[] BYTES = new byte[SIZE]; // we don't care what's inside
  
  public static void main(String[] args) throws IOException {
    ByteArrayOutputStream os = new ByteArrayOutputStream();
    os.write(BYTES);
    os.close();
    
    InputStream is = new ByteArrayInputStream(os.toByteArray());
    byte[] bytes = new byte[SIZE];
    int bytesRead = is.read(bytes);
    System.out.println("Read " + bytesRead + " bytes.");
  }
}