TIL 38일차

프래그먼트

액티비티 위에서 동작하는 인터페이스

하나의 프래그먼트를 여러 액티비티에서 재사용할 수 있음

프래그먼트 사용 예제

1. 프래그먼트 파일 생성

   

2. xml 파일 정의

   

3. MainActivity에 Fragment 추가하기

 

프래그먼트의 데이터 전달

Activity > Fragment 데이터 전달

1. 보내는 코드

   binding.run {
               fragment1Btn.setOnClickListener{
                   // [1] Activity -> FirstFragment
                   val dataToSend = "Hello First Fragment! \n From Activity"
                   val fragment = FirstFragment.newInstance(dataToSend)
                   setFragment(fragment)
               }
   
               fragment2Btn.setOnClickListener {
                   // [1] Activity -> SecondFragment
                   val dataToSend = "Hello Second Fragment!\n From Activity"
                   val fragment = SecondFragment.newInstance(dataToSend)
                   setFragment(fragment)
               }​

2. 받는 코드

private var param1: String? = null

companion object {
        @JvmStatic
        fun newInstance(param1: String) =
            // [1] Activity -> FirstFragment
            FirstFragment().apply {
                arguments = Bundle().apply {
                    putString(ARG_PARAM1, param1)
                }
            }
}

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        // [1] Activity -> FirstFragment
        binding.tvFrag1Text.text = param1     
}

Fragment > Fragment 데이터 전달

1. 보내는 코드

   // [2] Fragment -> Fragment
           binding.btnGofrag2.setOnClickListener{
               val dataToSend = "Hello Fragment2! \n From Fragment1"
               val fragment2 = SecondFragment.newInstance(dataToSend)
               requireActivity().supportFragmentManager.beginTransaction()
                   .replace(R.id.frameLayout, fragment2)
                   .addToBackStack(null)
                   .commit()
           }​

2. 받는 코드

 

private const val ARG_PARAM1 = "param1"

class SecondFragment : Fragment() {

    private var param1: String? = null

    private var _binding: FragmentSecondBinding? = null
    private val binding get() = _binding!!


    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        arguments?.let {
            param1 = it.getString(ARG_PARAM1)
        }
    }

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View {
        _binding = FragmentSecondBinding.inflate(inflater, container, false)
        return binding.root
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        // [2] Fragment -> Fragment
        binding.tvFrag2Text.text = param1
    }


    companion object {
        @JvmStatic
        fun newInstance(param1: String) =
            // [1] Activity -> FirstFragment
            SecondFragment().apply {
                arguments = Bundle().apply {
                    putString(ARG_PARAM1, param1)
                }
            }
    }

    override fun onDestroyView() {
        super.onDestroyView()
        // Binding 객체 해제
        _binding = null
    }
}

 

 

Fragment > Activity 데이터 전달

1. 보내는 코드

   private const val ARG_PARAM1 = "param1"
   
   interface FragmentDataListener {
       fun onDataReceived(data: String)
   }
   
   class SecondFragment : Fragment() {
   
       // [3] SecondFragment -> Activity
       private var listener: FragmentDataListener? = null
   
       private var param1: String? = null
   
       private var _binding: FragmentSecondBinding? = null
       private val binding get() = _binding!!
   
   
       override fun onAttach(context: Context) {
           super.onAttach(context)
   
           // [3] SecondFragment -> Activity
           if (context is FragmentDataListener) {
               listener = context
           } else {
               throw RuntimeException("$context must implement FragmentDataListener")
           }
       }
   
       override fun onCreate(savedInstanceState: Bundle?) {
           super.onCreate(savedInstanceState)
   
           arguments?.let {
               param1 = it.getString(ARG_PARAM1)
           }
       }
   
       override fun onCreateView(
           inflater: LayoutInflater, container: ViewGroup?,
           savedInstanceState: Bundle?
       ): View {
           _binding = FragmentSecondBinding.inflate(inflater, container, false)
           return binding.root
       }
   
       override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
           super.onViewCreated(view, savedInstanceState)
           // [2] Fragment -> Fragment
           binding.tvFrag2Text.text = param1
   
           // [3] SecondFragment -> Activity
           binding.btnSendActivity.setOnClickListener{
               val dataToSend = "Hello from SecondFragment!"
               listener?.onDataReceived(dataToSend)
           }
       }
   
   
       companion object {
           @JvmStatic
           fun newInstance(param1: String) =
               // [1] Activity -> FirstFragment
               SecondFragment().apply {
                   arguments = Bundle().apply {
                       putString(ARG_PARAM1, param1)
                   }
               }
       }
   
       override fun onDestroyView() {
           super.onDestroyView()
           // Binding 객체 해제
           _binding = null
           listener = null
       }
   }​

2. 받는 코드

class MainActivity : AppCompatActivity(), FragmentDataListener {

    private val binding by lazy { ActivityMainBinding.inflate(layoutInflater) }

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

        binding.run {
            fragment1Btn.setOnClickListener{
                // [1] Activity -> FirstFragment
                val dataToSend = "Hello First Fragment! \n From Activity"
                val fragment = FirstFragment.newInstance(dataToSend)
                setFragment(fragment)
            }

            fragment2Btn.setOnClickListener {
                // [1] Activity -> SecondFragment
                val dataToSend = "Hello Second Fragment!\n From Activity"
                val fragment = SecondFragment.newInstance(dataToSend)
                setFragment(fragment)
            }
        }

        setFragment(FirstFragment())
    }

    private fun setFragment(frag : Fragment) {
        supportFragmentManager.commit {
            replace(R.id.frameLayout, frag)
            setReorderingAllowed(true)
            addToBackStack("")
        }
    }

    // [3] SecondFragment -> Activity
    override fun onDataReceived(data: String) {
        // Fragment에서 받은 데이터를 처리
        Toast.makeText(this, data, Toast.LENGTH_SHORT).show()
    }
}