[Android] Application

Application

설명

• 애플리케이션 컴포넌트 사이에서 공통 멤버를 사용할 수 있게 해주는 클래스
• 공통 초기화 로직이나 공통 데이터 등을 관리하는 목적으로 사용

코드

AppApplication

class AppApplication : Application() {
    companion object {
        var message = "Hello"
    }

    override fun onCreate() {
        super.onCreate()

        Toast.makeText(this, "App Start", Toast.LENGTH_SHORT).show()

        registerActivityLifecycleCallbacks(AppActivityLifecycleCallbacks()) // 모든 액티비티 Lifecycle 감시
    }

    inner class AppActivityLifecycleCallbacks : ActivityLifecycleCallbacks {
        override fun onActivityPaused(activity: Activity) {
            Log.d("TEST", "onActivityPaused - ${activity.javaClass.simpleName}")
        }

        override fun onActivityStarted(activity: Activity) {
            Log.d("TEST", "onActivityStarted - ${activity.javaClass.simpleName}")
        }

        override fun onActivityDestroyed(activity: Activity) {
            Log.d("TEST", "onActivityDestroyed - ${activity.javaClass.simpleName}")
        }

        override fun onActivitySaveInstanceState(activity: Activity, outState: Bundle) {
            Log.d("TEST", "onActivitySaveInstanceState - ${activity.javaClass.simpleName}")
        }

        override fun onActivityStopped(activity: Activity) {
            Log.d("TEST", "onActivityStopped - ${activity.javaClass.simpleName}")
        }

        override fun onActivityCreated(activity: Activity, savedInstanceState: Bundle?) {
            Log.d("TEST", "onActivityCreated - ${activity.javaClass.simpleName}")
        }

        override fun onActivityResumed(activity: Activity) {
            Log.d("TEST", "onActivityResumed - ${activity.javaClass.simpleName}")
        }
    }
}

manifests/AndroidManifest.xml

<application 
    ...
    android:name=".AppApplication">
    ...
</application>

MainActivity

class MainActivity : AppCompatActivity() {
    lateinit var binding: ActivityMainBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        binding = ActivityMainBinding.inflate(layoutInflater).apply {
            setContentView(root)
            lifecycleOwner = this@MainActivity
        }

        Toast.makeText(this, AppApplication.message, Toast.LENGTH_SHORT).show()
    }
}

참고

• https://uroa.tistory.com/43