Question

I’m new to Java and writing a program with its own network protocol via UDP/TCP. There’s such a packet in C:

struct test_package {
    u32 cmd;
    u32 args;
    u32 flags;
};

Taking UDP as example, what I get from the DatagramPacket is byte data[]. How can I convert it to a package struct?

If in C, it’s just (struct test_package *)data if there’s no alignment restriction.

Thanks

Answer 1

Java does not provide direct memory access, so you cannot cast it to a structure as you can in C. You have to parse the byte array yourself, for example:

byte data[] = ...;
DataInput input = new DataInputStream(new ByteArrayInputStream(data));

int cmd = input.readInt();
int args = input.readInt();
int flags = input.readInt();