This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
I think what the instructions want to make clear is don't worry about the endian format for the numbers (In other words, readShort/readInt/writeShort/etc specified in DataOutput and DataInput interfaces and implemented in DataInputStream and DataOutputStream classes will work fine).
They aren't telling you to implement DataInputStream, they are just describing the format of the numbers. DataInputStream and RandomAccessFile both get their functionality reading numbers from the DataInput interface. Don't sweat it.