a singleton class to check the network connection state, use both of the NetworkCallback and ConnectivityManager to support older devices

NetworkHelper.kt

package com.graymind75

import android.content.Context
import android.net.*
import android.os.Build
import androidx.annotation.RequiresApi

/**
 * singleton class to check the network connection state
 * It's use the old ConnectivityManager.activeNetworkInfo way for pre LOLLIPOP
 * and the new API named NetworkCallback for the devices with Android API version LOLLIPOP and above
 *
 * required permissions:
 *     <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
 *     <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
 */
object NetworkHelper {
    private val connectivityManager: ConnectivityManager = AppClass.instance.applicationContext
        .getSystemService(Context.CONNECTIVITY_SERVICE)
            as ConnectivityManager
    private var isNetworkAvailable = false;

    /**
     * check the SDK_INT of device and register to the new API for connection callbacks
     * because the new API only support the API 21 and above
     */
    init {
        if (Build.VERSION.SDK_INT > Build.VERSION_CODES.LOLLIPOP) {
            val networkRequest = NetworkRequest.Builder()
                .addTransportType(NetworkCapabilities.TRANSPORT_WIFI)
                .addTransportType(NetworkCapabilities.TRANSPORT_CELLULAR)
                .build()

            connectivityManager.registerNetworkCallback(networkRequest, networkCallback())
        }
    }

    /**
     * new API callbacks to determine which status we currently in
     * we need the below callbacks:
     * - onAvailable: device connected to a network of course
     * - onLost: when the connection completely lost
     * - onUnavailable: when somehow the connection cannot be reached
     */
    private fun networkCallback() = @RequiresApi(Build.VERSION_CODES.LOLLIPOP)
    object: ConnectivityManager.NetworkCallback() {

        override fun onLost(network: Network) {
            super.onLost(network)
            isNetworkAvailable = false
        }

        override fun onUnavailable() {
            super.onUnavailable()
            isNetworkAvailable = false
        }

        override fun onAvailable(network: Network) {
            super.onAvailable(network)
            isNetworkAvailable = true
        }

    }

    /**
     * check the network state with the old way for APIs below LOLLIPOP
     */
    private fun checkIsNetworkAvailable(): Boolean {
        val activeNetworkInfo = connectivityManager.activeNetworkInfo
        return activeNetworkInfo != null && activeNetworkInfo.isConnected
    }

    /**
     * the function for call from outside the class to check the connection status
     * first check the SDK_INT then provide the status with the right API
     */
    fun checkNetwork(): Boolean {
        if (Build.VERSION.SDK_INT > Build.VERSION_CODES.LOLLIPOP)
            return isNetworkAvailable
        return checkIsNetworkAvailable()
    }

}

hey,
can you please give an example of getting these callbacks on activity/fragments.

@surajp-appdesk

Hi, I assume you are using minSdk 23
So:

class MainActivity : AppCompatActivity(), ConnectivityManager.NetworkCallback {
    private lateinit var connectivityManager: ConnectivityManager
    var isNetworkAvailable = false

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        connectivityManager = getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
        init()
    }

    fun init() {
        val networkRequest = NetworkRequest.Builder()
            .addTransportType(NetworkCapabilities.TRANSPORT_WIFI)
            .addTransportType(NetworkCapabilities.TRANSPORT_CELLULAR)
            .build()

        connectivityManager.registerNetworkCallback(networkRequest, this@MainActivity)
    }

    override fun onLost(network: Network) {
        super.onLost(network)
        isNetworkAvailable = false
    }

    override fun onUnavailable() {
        super.onUnavailable()
        isNetworkAvailable = false
    }

    override fun onAvailable(network: Network) {
        super.onAvailable(network)
        isNetworkAvailable = true
    }

}