What are java equivalents to JS push, concat, unshift?

Question

I'm trying to convert the following JS to Java:

serializeSig:function(r,s){
var rBa=r.toByteArraySigned();
var sBa=s.toByteArraySigned();
var sequence=[];
sequence.push(2);
sequence.push(rBa.length);
sequence=sequence.concat(rBa);
sequence.push(2);
sequence.push(sBa.length);
sequence=sequence.concat(sBa);
sequence.unshift(sequence.length);
sequence.unshift(48);
return sequence
}

I think push would translate to add, concat to some kind of addAll, but what is unshift? And of what type would my variables in java be?

Answer 1

myArray.unshift(obj) corresponds to myList.add(0, obj).

A byte array in Java is byte[]. A list of byte arrays would be a List<byte[]>. (That's java.util.List, not java.awt.List, just in case you get the wrong import.)

EDIT: Looks like you are trying to create a byte array, not a list of byte arrays. In that case, you should use a java.nio.ByteBuffer, or possibly a java.io.ByteArrayOutputStream. The latter has to be written to sequentially -- you cannot do the equivalent of an unshift.