Android in A..Z - Lifecycle (Scope)

ViewModelScope

ViewModel마다 존재하는 Scope이다. ViewModel이 삭제되면 자동으로 취소된다.

class ExampleViewModel : ViewModel() {
    init {
        viewModelScope.launch {
            /*
            ViewModel이 사라지면 종료된다.
             */
        }
    }
}

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LifeCycleScope

LifeCycle 객체마다 존재하는 Scope이다. Create, Start, Resume 3가지의 Mode를 지원하고 Active상태(화면에 보이는 상태)일 때만 수행된다.

class CoroutineFragment : BaseFragment<FragmentCoroutineBinding>(R.layout.fragment_coroutine) {
    private var count = 0
    private val logList by lazy { ArrayList<String>() }
    private val logAdapter by lazy { LogAdapter().apply { submitList(logList) } }

    override fun init() {
        initCoroutine()
        initSupportActionbar()
        initRecyclerView()
        initOnNavigate()
    }

    private fun initCoroutine() {
        viewLifecycleOwner.lifecycleScope.launch {
            whenCreated {
                writeLog("${SimpleDateFormat.getTimeInstance().format(System.currentTimeMillis())} launch - launchWhenCreated")
            }
            whenStarted {
                writeLog("${SimpleDateFormat.getTimeInstance().format(System.currentTimeMillis())} launch - launchWhenStarted")
            }
            whenResumed {
                writeLog("${SimpleDateFormat.getTimeInstance().format(System.currentTimeMillis())} launch - launchWhenResumed")
            }
        }

        viewLifecycleOwner.lifecycleScope.launchWhenCreated {
            writeLog("${SimpleDateFormat.getTimeInstance().format(System.currentTimeMillis())} launch - launchWhenCreated(${count++})")
        }

        viewLifecycleOwner.lifecycleScope.launchWhenStarted {
            writeLog("${SimpleDateFormat.getTimeInstance().format(System.currentTimeMillis())} launch - launchWhenStarted(${count++})")
        }

        viewLifecycleOwner.lifecycleScope.launchWhenResumed {
            while (true) {
                writeLog("${SimpleDateFormat.getTimeInstance().format(System.currentTimeMillis())} launch - launchWhenResumed(${count++})")
                delay(1000L)
            }
        }
    }

    private fun initSupportActionbar() {
        setSupportActionBar(binding.toolbar)
    }

    private fun initRecyclerView() {
        with(binding.recyclerView) {
            adapter = logAdapter
        }
    }

    private fun initOnNavigate() {
        binding.setOnNavigate {
            findNavController().navigate(CoroutineFragmentDirections.actionCoroutineFragmentToCoroutineNextFragment())
        }
    }

    private fun writeLog(log: String) {
        logList.add(log)
        logAdapter.notifyItemInserted(logList.lastIndex)
    }
}