ndroid_Review_23
IntentFilter & Broadcast Receiver
tips:
code in Fragement is different from code in Activity due to Lifecycle, however the background phases are all the same: stop, start, pause, resume.
// IPC & INTENT
import android.content.BroadcastReceiver
import android.content.Intent
import android.content.IntentFilter
// WIFI & CONTEXT
import android.net.wifi.WifiManager
import android.content.Context
// WIDGET
import android.widget.Switch
import android.widget.Toast
class PlaceholderFragment : Fragment() {
lateinit var wifiSwitch: Switch
lateinit var wifiManager: WifiManager
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
}
// all view display in this phase
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
val root = inflater.inflate(R.layout.fragment_main, container, false)
val textView: TextView = root.findViewById(R.id.section_label)
// Tab 功能 -------------------------
pageViewModel.text.observe(this, Observer<String> {
textView.text = it
})
/*
* 1. You can directly use the activity or context reference in your fragment.
* So instead of using this and applicationContext use getActivity() ot getContext() method.
* 2. remove the setContentView() from on create as its of no need cause you are already inflating the view properly in onCreateView().
* */
// SYS WIFI ---------------------------
// activity 無須 root, 僅 fragment 需要
wifiSwitch = root.findViewById(R.id.wifiSwitch)
// activity 無須 context, 僅 fragment 需要
wifiManager = context!!.getSystemService(Context.WIFI_SERVICE) as WifiManager
wifiSwitch.setOnCheckedChangeListener { _, isChecked ->
if (isChecked) {
//wifiManager.connectionInfo
//wifiManager.dhcpInfo
wifiManager.isWifiEnabled = true
wifiSwitch.text = "WiFi is opened"
} else {
wifiManager.isWifiEnabled = false
wifiSwitch.text = "WiFi is closed"
}
}
return root
}
// background -> foreground
override fun onStart() {
super.onStart()
// activity 無須 context, 僅 fragment 需要
val intentFilter = IntentFilter(WifiManager.WIFI_STATE_CHANGED_ACTION)
context!!.registerReceiver(wifiStateReceiver, intentFilter)
}
// foreground -> background
override fun onStop() {
super.onStop()
// activity 無須 context, 僅 fragment 需要
context!!.unregisterReceiver(wifiStateReceiver)
}
private val wifiStateReceiver: BroadcastReceiver = object : BroadcastReceiver() {
override fun onReceive(context: Context, intent: Intent) {
when (intent.getIntExtra(WifiManager.EXTRA_WIFI_STATE,
WifiManager.WIFI_STATE_UNKNOWN)) {
WifiManager.WIFI_STATE_ENABLED -> {
wifiSwitch.isChecked = true
wifiSwitch.text = "WiFi is ON"
Toast.makeText(getActivity(), "Wifi is already On in background", Toast.LENGTH_SHORT).show()
}
WifiManager.WIFI_STATE_DISABLED -> {
wifiSwitch.isChecked = false
wifiSwitch.text = "WiFi is OFF"
Toast.makeText(getActivity(), "Wifi is already Off in background", Toast.LENGTH_SHORT).show()
}
}
}
} // this BR object
......
} // this class
ref:
https://www.tutorialspoint.com/how-to-use-broadcastreceiver-in-kotlin (BR)