kotlin reading from file into byte array

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?:

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The easiest way is to use
```kotlin
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.
```kotlin
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)
}
}
```

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))