안드로이드 앱 개발 연습 - 4 | Fragment

Activity에 Fragment 추가

frameLayout

MainActivity.kt

class MainActivity : AppCompatActivity() {
    val binding by lazy { ActivityMainBinding.inflate(layoutInflater) }

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

        setFragment()
    }

    fun setFragment() {
    	// Transaction: begin transaction => add fragment => commit transaction
        
        val listFragment: ListFragment = ListFragment()
        val transaction = supportFragmentManager.beginTransaction() // begin transaction
        transaction.add(R.id.frameLayout, listFragment) // add fragment
        transaction.commit() // commit transaction
    }
}

 

ListFragment.kt

class ListFragment : Fragment() {
    lateinit var binding: FragmentListBinding

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

 

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <FrameLayout
        android:id="@+id/frameLayout"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="parent">

    </FrameLayout>

</androidx.constraintlayout.widget.ConstraintLayout>

fragmentContainerView

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <androidx.fragment.app.FragmentContainerView
        ...
        tools:layout="@layout/fragment_list" />

</androidx.constraintlayout.widget.ConstraintLayout>

---

Fragment 화면 전환 (MainActivity에 Fragment 연결)

MainActivity.kt

class MainActivity : AppCompatActivity() {
    val binding by lazy { ActivityMainBinding.inflate(layoutInflater) }

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

        setFragment()
    }

    fun setFragment() {
    	// Transaction: begin transaction => add fragment => commit transaction
        
        val listFragment: ListFragment = ListFragment()
        val transaction = supportFragmentManager.beginTransaction() // begin transaction
        transaction.add(R.id.frameLayout, listFragment) // add fragment
        transaction.commit() // commit transaction
    }
    
    fun goDetail() {
        val detailFragment = DetailFragment()
        val transaction = supportFragmentManager.beginTransaction() // begin transaction
        transaction.add(R.id.frameLayout, detailFragment) // add fragment
        transaction.addToBackStack("detail") // for using android back button
        transaction.commit() // commit transaction
    }

    fun goBack() {
        onBackPressed() // Activity's Original Method
    }
}

ListFragment.kt

class ListFragment : Fragment() {
    var mainActivity: MainActivity? = null
    lateinit var binding: FragmentListBinding

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
        binding = FragmentListBinding.inflate(inflater, container, false)
        binding.nextBtn.setOnClickListener { mainActivity?.goDetail() }
        return binding.root
    }

    override fun onAttach(context: Context) {
        super.onAttach(context)
        if (context is MainActivity) mainActivity = context
    }
}

DetailFragment.kt

class DetailFragment : Fragment() {
    lateinit var mainActivity: MainActivity
    lateinit var binding: FragmentDetailBinding

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
        binding = FragmentDetailBinding.inflate(inflater, container, false)
        binding.backBtn.setOnClickListener { mainActivity.goBack() }
        return binding.root
    }

    override fun onAttach(context: Context) {
        super.onAttach(context)
        mainActivity = context as MainActivity
    }
}

---

Fragment 값 전달

Fragment 생성 시 값 전달 (arguments)

MainActivity.kt

class MainActivity : AppCompatActivity() {
    val binding by lazy { ActivityMainBinding.inflate(layoutInflater) }
    lateinit var listFragment: ListFragment

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

        setFragment()
    }

    fun setFragment() {
        listFragment = ListFragment()
        val transaction = supportFragmentManager.beginTransaction() // begin transaction
        transaction.add(R.id.frameLayout, listFragment) // add fragment
        transaction.commit() // commit transaction

        // --------------------------------------------------
        var bundle = Bundle()
        bundle.putString("key1", "List Fragment")
        bundle.putInt("key2", 2022)
        listFragment.arguments = bundle
        // --------------------------------------------------
    }

    fun goDetail() {
        val detailFragment = DetailFragment()
        val transaction = supportFragmentManager.beginTransaction() // begin transaction
        transaction.add(R.id.frameLayout, detailFragment) // add fragment
        transaction.addToBackStack("detail")
        transaction.commit() // commit transaction
    }

    fun goBack() {
        onBackPressed() // Activity's Original Method
    }
}

 

ListFragment.kt

class ListFragment : Fragment() {
    var mainActivity: MainActivity? = null
    lateinit var binding: FragmentListBinding

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
        binding = FragmentListBinding.inflate(inflater, container, false)
        binding.nextBtn.setOnClickListener { mainActivity?.goDetail() }
        // ------------------------------------------------------------
        binding.textTitle.text = arguments?.getString("key1")
        binding.textValue.text = "${arguments?.getInt("key2")}"
        // ------------------------------------------------------------
        return binding.root
    }

    override fun onAttach(context: Context) {
        super.onAttach(context)
        if (context is MainActivity) mainActivity = context
    }
}

​이미 생성된 Fragment에 값 전달

MainActivity.kt

class MainActivity : AppCompatActivity() {
    val binding by lazy { ActivityMainBinding.inflate(layoutInflater) }
    lateinit var listFragment: ListFragment

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

        setFragment()

        // --------------------------------------------------------------------------------
        var sendInput: String? = null
        binding.sendInput.addTextChangedListener { sendInput = it.toString() }
        binding.sendBtn.setOnClickListener { listFragment.setValue(sendInput?:"") }
        // --------------------------------------------------------------------------------
    }

    fun setFragment() {
        listFragment = ListFragment()
        val transaction = supportFragmentManager.beginTransaction() // begin transaction
        transaction.add(R.id.frameLayout, listFragment) // add fragment
        transaction.commit() // commit transaction

        var bundle = Bundle()
        bundle.putString("key1", "List Fragment")
        bundle.putInt("key2", 2022)
        listFragment.arguments = bundle
    }

    fun goDetail() {
        val detailFragment = DetailFragment()
        val transaction = supportFragmentManager.beginTransaction() // begin transaction
        transaction.add(R.id.frameLayout, detailFragment) // add fragment
        transaction.addToBackStack("detail")
        transaction.commit() // commit transaction
    }

    fun goBack() {
        onBackPressed() // Activity's Original Method
    }
}

 

ListFragment

class ListFragment : Fragment() {
    var mainActivity: MainActivity? = null
    lateinit var binding: FragmentListBinding

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
        binding = FragmentListBinding.inflate(inflater, container, false)
        binding.nextBtn.setOnClickListener { mainActivity?.goDetail() }
        binding.textTitle.text = arguments?.getString("key1")
        binding.textTitle.text = "${arguments?.getInt("key2")}"
        return binding.root
    }

    override fun onAttach(context: Context) {
        super.onAttach(context)
        if (context is MainActivity) mainActivity = context
    }

    // --------------------------------------------------
    fun setValue(value: String?) {
        binding.textFromActivity.text = value
    }
    // --------------------------------------------------
}

Fragment 간 값 전달

build.gradle (:app)

...

dependencies {
    def fragment_version = "1.3.0-beta02"
    implementation "androidx.fragment:fragment:$fragment_version"
    implementation "androidx.fragment:fragment-ktx:$fragment_version"
    ...
}

 

ListFragment.kt

class ListFragment : Fragment() {
    var mainActivity: MainActivity? = null
    lateinit var binding: FragmentListBinding

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
        binding = FragmentListBinding.inflate(inflater, container, false)
        binding.nextBtn.setOnClickListener { mainActivity?.goDetail() }
        binding.textTitle.text = arguments?.getString("key1")
        binding.textTitle.text = "${arguments?.getInt("key2")}"
        return binding.root
    }

    // --------------------------------------------------------------------------------
    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        val bundle = Bundle()
        var toFragmentInput: String? = null

        binding.toFragmentInput.addTextChangedListener { toFragmentInput = it.toString() }
        binding.nextBtn.setOnClickListener {
            bundle.putString("valueKey", toFragmentInput?: "")
            setFragmentResult("request", bundle)
            mainActivity?.goDetail()
        }
    }
    // --------------------------------------------------------------------------------
    
    override fun onAttach(context: Context) {
        super.onAttach(context)
        if (context is MainActivity) mainActivity = context
    }

    fun setValue(value: String?) {
        binding.textFromActivity.text = value
    }
}

 

DetailFragment.kt

class DetailFragment : Fragment() {
    lateinit var mainActivity: MainActivity
    lateinit var binding: FragmentDetailBinding

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
        binding = FragmentDetailBinding.inflate(inflater, container, false)
        binding.backBtn.setOnClickListener { mainActivity.goBack() }
        return binding.root
    }

    // ----------------------------------------------------------------------
    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        setFragmentResultListener("request") { requestKey, bundle ->
            bundle.getString("valueKey")?.let {
                binding.fromFragmentText.text = it
            }
        }
    }
    // ----------------------------------------------------------------------

    override fun onAttach(context: Context) {
        super.onAttach(context)
        mainActivity = context as MainActivity
    }
}