InputStream for Android Things UartDevice

UartInputStream.kt

package com.mycompany.uartproj

import com.google.android.things.pio.UartDevice
import java.io.InputStream

class UartInputStream(private val uartDevice: UartDevice) : InputStream() {

    override fun read(): Int {
        val byteArray = ByteArray(1)
        while (true) {
            val count = uartDevice.read(byteArray, 1)
            if (count == 0) {
                Thread.sleep(20)
                continue
            }
            return byteArray[0].toInt()
        }
    }

    override fun read(b: ByteArray?, off: Int, len: Int): Int {
        if (b == null) {
            throw NullPointerException()
        } else if (off < 0 || len < 0 || b.size - off < len) {
            throw IndexOutOfBoundsException()
        } else if (len == 0) {
            return 0
        }

        val byteArray = ByteArray(len)
        val count = uartDevice.read(byteArray, len)
        System.arraycopy(byteArray, 0, b, off, len)

        return count
    }

    override fun available(): Int {
         // What to do?
    }

}