EditTextChannel.kt

import android.text.Editable
import android.text.TextWatcher
import android.widget.EditText
import kotlinx.coroutines.experimental.channels.Channel
import kotlinx.coroutines.experimental.channels.ReceiveChannel
import kotlinx.coroutines.experimental.channels.sendBlocking
import kotlinx.coroutines.experimental.launch

object EditTextChannel {
    fun empty(editText: EditText): ReceiveChannel<Boolean> = ConflatedChannel<Boolean>().apply {
        editText.addTextChangedListener(object : TextWatcher {
            override fun afterTextChanged(s: Editable?) {
                // no op
            }

            override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {
                // no op
            }

            override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {
                offer(s.isNullOrEmpty())
            }
        })

        // initial value
        offer(editText.text.isEmpty())
    }
}

Use.kt

launch { 
  EditTextChannel.empty(editForm).consumeEach {
      submitButton.isEnabled = !it
  }
}