java 14 and JEP 370: Foreign-Memory Access API-- Array Of Bytes.

[Henry Jen]

For primitive types, you can use the combination of MemoryAddress.copy and MemorySegment.ofArray.

MemoryAddress.copy(MemorySegment.ofArray(byteArrayString).baseAddress(), address, byteArrayString.length);

Cheers,
Henry



> On Mar 25, 2020, at 8:02 AM, Ahmed Hamdallah <ahmdprog at gmail.com> wrote:
> 
> hello,
> 
> Regarding java 14 new feature of new Foreign-Memory API. it is actually bit complicated for me regarding classes SequenceLayout & VarHandle.
> 
> since it is a new feature, i could not find many example to access MemorySegment data.
> 
> my question, using MemorySegment & VarHandle classes how to read/write array of bytes at one shot. not byte by byte.
> 
> Yes, I am aware of asByteBuffer(). but as per documentation the main reason for this new Memory Segment access is to avoid ByteBuffer class.
> 
> this is example
> 
> byte[] bytesArrayString = "Hello MemorySegment".getBytes();
> 
>    MemoryAddress address = MemorySegment.allocateNative(4096).baseAddress();
> 
>    SequenceLayout bytes = MemoryLayout.ofSequence(bytesArrayString.length, MemoryLayouts.JAVA_BYTE);
> 
>    VarHandle byteHandle = bytes.varHandle(byte.class, MemoryLayout.PathElement.sequenceElement());
> 
>    byteHandle.set(address.addOffset(0), (byte[]) bytesArrayString);
> 
>    byte value[] = (byte[]) byteHandle.get(address.addOffset(0));
> 
>    System.out.println("Memory Value: " + value.length + new String(value));
> 
> error
> 
> java.lang.invoke.WrongMethodTypeException: cannot convert MethodHandle(VarHandle,MemoryAddressProxy,long,byte)void to (VarHandle,MemoryAddress,long,byte[])void
> java<https://stackoverflow.com/questions/tagged/java>