(Android) 간단하게 Activity, Fragment 보여주기

이번 포스팅은 Activity를 start하거나 Fragment를 보여주는 코드를 어떻게 하면 간단하게 보여줄 수 있는지 소개하고자 합니다.

Activity

기존 스타일

// in Activity
val intent = Intent(this, DestinationActivity::class.java)
intent.putExtra("key1", "value1")
intent.putExtra("key2", "value2")
startActivity(intent)

// in Fragment
val intent = Intent(requireContext(), DestinationActivity::class.java)
intent.putExtra("key1", "value1")
intent.putExtra("key2", "value2")
startActivity(intent)

Companion

ActivityTemplate.kt

abstract class ActivityTemplate<T : Activity> {

    private val clazz: Class<*>
        get() = ((this.javaClass.genericSuperclass as ParameterizedType?)?.actualTypeArguments
            ?.get(0) as Class<*>)

    fun start(
        context: Context,
        vararg param: Pair<String, Any?>,
        intentAction: Intent.() -> Unit = {}
    ) {
        context.startActivity(createIntent(context, *param).apply(intentAction))
    }

    fun createIntent(context: Context, vararg param: Pair<String, Any?>) =
        Intent(context, clazz).apply { putExtras(bundleOf(*param)) }

}

DestinationActivity.kt

class DestinationActivity : AppCompatActivity(R.layout.activity_destination) {
    companion object : ActivityTemplate<DestinationActivity>()
}

사용하기

// in Activity
DestinationActivity.start(this, "key1" to "value1", "key2" to "value2")

// in Fragment
DestinationActivity.start(requireContext(), "key1" to "value1", "key2" to "value2")

기존 스타일보다 사용하기는 편해졌지만 Activity마다 companion object를 만들고 ActivityTemplate을 상속해야 하는 작은 불편함이 있습니다.

Extension function

IntentExtension.kt

fun <T> createIntent(
    context: Context,
    clazz: Class<out T>,
    params: Array<out Pair<String, Any?>>
) = Intent(context, clazz).apply { putExtras(bundleOf(*params)) }

ContextExtension.kt

inline fun <reified T : Activity> Context.startActivity(
    vararg param: Pair<String, Any?>,
    intentAction: Intent.() -> Unit = {}
) {
    val intent = createIntent(this, T::class.java, param).apply(intentAction)
    startActivity(intent)
}

FragmentExtension.kt

inline fun <reified T : Activity> Fragment.startActivity(
    vararg param: Pair<String, Any?>,
    intentAction: Intent.() -> Unit = {}
) {
    val intent = createIntent(requireContext(), T::class.java, param).apply(intentAction)
    startActivity(intent)
}

사용하기

// in Activity
startActivity<DestinationActivity>("key1" to "value1", "key2" to "value2")

// in Fragment
startActivity<DestinationActivity>("key1" to "value1", "key2" to "value2")

기존 스타일과 비슷한 형태지만 Intent를 만들 필요 없이 사용 할 수 있고 Companion 스타일처럼 추가 작업을 할 필요 없어서 간단하게 사용 할 수 있습니다.

Fragment

기존 스타일

supportFragmentManager.findFragmentByTag(tag)
    ?: DestinationFragment().also { newFragment ->
        val bundle = Bundle()
        bundle.putString("key1", "value1")
        bundle.putString("key2", "value2")
        newFragment.arguments = bundle
        supportFragmentManager.beginTransaction()
            .replace(R.id.fl_container, newFragment, tag)
            .commit()
    }

Companion

FragmentTemplate.kt

@Suppress("UNCHECKED_CAST")
abstract class FragmentTemplate<out T : Fragment> {
    private val clazz: Class<*>
        get() = ((this.javaClass.genericSuperclass as ParameterizedType?)?.actualTypeArguments
            ?.get(0) as Class<*>)

    fun replace(
        fragmentManager: FragmentManager,
        @IdRes containerViewId: Int,
        vararg param: Pair<String, Any?>,
        tag: String = clazz.simpleName
    ) {
        find(fragmentManager, tag) ?: newInstance(*param).let { newFragment ->
            fragmentManager.beginTransaction()
                .replace(containerViewId, newFragment, tag)
                .commitAllowingStateLoss()
        }
    }

    fun find(fragmentManager: FragmentManager, tag: String = clazz.simpleName) =
        fragmentManager.findFragmentByTag(tag) as? T

    fun newInstance(vararg param: Pair<String, Any?>) =
        (clazz.newInstance() as Fragment).apply { arguments = bundleOf(*param) } as T
}

DestinationFragment.kt

class DestinationFragment : Fragment(R.layout.destination) {
    companion object : FragmentTemplate<DestinationFragment>()
}

사용하기

// in Activity
DestinationFragment.replace(
    supportFragmentManager,
    R.id.fl_container,
    "key1" to "value1",
    "key2" to "value2"
)

// in Fragment
DestinationFragment.replace(
    fragmentManager,
    R.id.fl_container,
    "key1" to "value1",
    "key2" to "value2"
)

기존 스타일보다 사용하기는 편해졌지만 Fragment마다 companion object를 만들고 FragmentTemplate을 상속해야 하는 작은 불편함이 있습니다.

Extension function

FragmentActivityExtension.kt

inline fun <reified T : Fragment> FragmentActivity.replaceFragment(
    @IdRes containerViewId: Int,
    vararg param: Pair<String, Any?>,
    tag: String = T::class.java.simpleName
) {
    findFragment() ?: T::class.java.newInstance().also { newFragment ->
        newFragment.arguments = bundleOf(*param)
        supportFragmentManager.beginTransaction()
            .replace(containerViewId, newFragment, tag)
            .commitAllowingStateLoss()
    }

}

inline fun <reified T : Fragment> FragmentActivity.findFragment(tag: String = T::class.java.simpleName): T? {
    return supportFragmentManager.findFragmentByTag(tag) as? T
}

FragmentExtension.kt

inline fun <reified T : Fragment> Fragment.replaceFragment(
    @IdRes containerViewId: Int,
    vararg param: Pair<String, Any?>,
    tag: String = T::class.java.simpleName
) {
    findFragment() ?: T::class.java.newInstance().also { newFragment ->
        newFragment.arguments = bundleOf(*param)
        childFragmentManager.beginTransaction()
            .replace(containerViewId, newFragment, tag)
            .commitAllowingStateLoss()
    }
}

inline fun <reified T : Fragment> Fragment.findFragment(tag: String = T::class.java.simpleName): T? {
    return childFragmentManager.findFragmentByTag(tag) as? T
}

사용하기

// in Activity
replaceFragment<DestinationFragment>(
    R.id.fl_container,
    "key1" to "value1",
    "key2" to "value2"
)

// in Fragment
replaceFragment<DestinationFragment>(
    R.id.fl_container,
    "key1" to "value1",
    "key2" to "value2"
)

Activity의 Extension function과 비슷한 형태이고 Companion 스타일처럼 추가 작업을 할 필요 없어서 간단하게 사용 할 수 있습니다.

참고자료

bundleOf로 데이터 편하게 전달하기

(Android) bundleOf로 데이터 편하게 전달하기

 

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