MainActivity.kt

class MainActivity : AppCompatActivity() {

    var objectA = null
    
    override fun onCreate(savedInstanceState: Bundle?) {
        ////
        initObjectA()
    }
    override fun onResume() {
        super.onResume()
        registerListenerAChange()
    }
    override fun onStop() {
        super.onStop()
        unRegisterListenerAChange()
    }
    override fun onDestroy() {
        super.onDestroy()
        releaseAll()
    }
    private fun initObjectA() {
        objectA = getAFromFrameworkApi()
    }
    private fun registerListenerAChange() {
        objectA.registerStateChange()
    }
    private fun unRegisterListenerAChange() {
        objectA.unregister()
    }
    private fun releaseAll() {
        objectA.release()
        objectA = null
    }