How do I read bytes into a Byte Array? In java I used to initialize byte array as byte[] b = new byte[100] and then pass that to the corresponding method. However in Kotlin, I am unable to initialize ByteArray with how many bytes the buffer should have.
In other words, how do I use this function?: https://developer.android.com/reference/kotlin/java/io/RandomAccessFile#read(kotlin.ByteArray)
The easiest way is to use
File("aaa").readBytes() That one will read the whole file into the ByteArray. But you should carefully know you have enough RAM in the heap to do so
The ByteArray can be created via ByteArray(100) call, where 100 is the size of it
For the RandomAccessFile, it is probably better to use at the readFully function, which reads exactly the requested amount of bytes.
The classic approach is possible to read a file by chunks, e.g.
val buff = ByteArray(1230) File("aaa").inputStream().buffered().use { input -> while(true) { val sz = input.read(buff) if (sz <= 0) break ///at that point we have a sz bytes in the buff to process consumeArray(buff, 0, sz) } } 
val buf: ByteArray(100), it shows error at ( saying unexpected tokens...
I found this worked nicely:
fun File.chunkedSequence(chunk: Int): Sequence<ByteArray> { val input = this.inputStream().buffered() val buffer = ByteArray(chunk) return generateSequence { val red = input.read(buffer) if (red >= 0) buffer.copyOf(red) else { input.close() null } } } Use it like this.
file.chunkedSequence(CHUNK_SIZE).forEach { // Do something with `it` } Not an exact match to your question but this is the question that came up when I was looking to chunk a file into a sequence of byte arrays.
File.readBytes() //limited 2GB Don't forget it has an internal limitation of 2 GB byte array size. So to read all bytes we should use stream like:
FileInputStream(File(uri)).use { val allBytes = it.readBytes() } Also you can use readAllBytes for Android API >= 26:
Files.readAllBytes(Paths.get(filePath)) 