writeChars() has no readChars() counterpart. writeBytes() has no
readBytes() counterpart -- the best is readFully() which reads an
array, although writeChars() writes out a String. The length of the
String is not saved.

In general, DataInputStream and DataOutputStream should be virtual
counterparts of each other, with each write call having a read
equivalent. This would reduce confusion, and ensure that functionality
matched.