Question

Given a generic array T[], where T extends java.lang.Number, I would like to write the array to a byte[], using ByteArrayOutputStream. java.io.DataOutput (and an implementation such as java.io.DataOutputStream appears close to what I need, but there is no generic way to write the elements of the T[] array. I want to do something like

ByteArrayOutputStream out = new ByteArrayOutputStream();
DataOutputStream dataOut = new DataOutputStream(out);

for (T v : getData()) {
  dataOut.write(v); // <== uh, oh
}

but there is no generic <T> void write(T v) method on DataOutput.

Is there any way to avoid having to write a whole bunch of isntanceof spaghetti?

Clarification

The byte[] is being sent to a non-Java client, so object serialization isn’t an option. I need, for example, the byte[] generated from a Float[] to be a valid float[] in C.

Answer 1

No, there isn’t. The instanceof “spaghetti” would have to exist somewhere anyway. Make a generic method that does that:

public <T> void write(DataOutputStream stream, T object) {
   // instanceofs and writes here
}