티스토리 뷰

Android/Kotlin

[Kotlin]  Fragment에서 Child Fragment로 데이터 전달

혀가 길지 않은 개발자 2020. 10. 24. 17:19

1. Interface를 이용하는 방법

2. Bundle 객체를 생성해서 Fragment의 전달인자로 보내는 방법

3. requireActivity()를 전달인자로 사용한 ViewModel을 공유하는 방법

4. requireParentFragment()를 전달인자로 사용한 ViewModel을 공유하는 방법

1. Interface를 이용하는 방법

 

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="40dp"
    android:paddingRight="40dp"
    android:paddingLeft="40dp"
    android:orientation="vertical"
    android:gravity="center"
    tools:context=".MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:layout_marginBottom="20dp"
        android:textAllCaps="false"
        android:textSize="22dp"
        android:text="MainActivity Area"
        android:textStyle="bold|italic"/>

    <FrameLayout
        android:id="@+id/frameLayoutParent"
        android:layout_width="match_parent"
        android:background="#DDDDDD"
        android:layout_height="0dp"
        android:layout_weight="1"/>

</LinearLayout>

activity_main.xml

 

 

 

fragment_parent.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingLeft="40dp"
    android:paddingRight="40dp"
    android:paddingBottom="40dp"
    android:orientation="vertical"
    android:gravity="center">

    <TextView
        android:id="@+id/tvParent"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:textAllCaps="false"
        android:text="ParentFragment Area"
        android:textSize="20dp"
        android:textStyle="bold|italic"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintBottom_toBottomOf="parent" />

    <Button
        android:id="@+id/btnParent"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:layout_marginBottom="20dp"
        android:textAllCaps="false"
        android:text="Parent -> Child"/>

    <FrameLayout
        android:id="@+id/frameLayoutChild"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="#BBBBBB"/>

</LinearLayout>

fragment_parent.xml

 

 

 

fragment_child.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:gravity="top|center">

    <TextView
        android:id="@+id/tvChild"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:textAllCaps="false"
        android:text="ChildFragment Area"
        android:textSize="18dp"
        android:textStyle="bold|italic"/>

    <Button
        android:id="@+id/btnChild"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:textAllCaps="false"
        android:text="Child -> Parent"/>

</LinearLayout>

fragment_child.xml

 

 

 

FragmentListener.kt

package com.jwsoft.kotlinproject

interface FragmentListener {
    fun onReceivedData(data: String)
}

 

 

 

 

MainActivity.kt

package com.jwsoft.kotlinproject

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        var transaction = supportFragmentManager.beginTransaction()
        transaction.add(R.id.frameLayoutParent, FragmentParent()).commit()
    }

}

 

 

 

 

FragmentParent.kt

package com.jwsoft.kotlinproject

import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.fragment.app.Fragment
import kotlinx.android.synthetic.main.fragment_parent.*

class FragmentParent : Fragment(), FragmentListener {

    private lateinit var mFragmentListener: FragmentListener
    private var fragmentChild = FragmentChild()

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        return inflater.inflate(R.layout.fragment_parent, container, false)
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        val transaction = childFragmentManager.beginTransaction()
        transaction.add(R.id.frameLayoutChild, fragmentChild).commit()

        btnParent.setOnClickListener {
            mFragmentListener = fragmentChild
            mFragmentListener.onReceivedData("Parent -> Child")
        }
    }

    override fun onReceivedData(data: String) {
        tvParent.text = data
    }
}

 

 

 

 

 

FragmentChild.kt

package com.jwsoft.kotlinproject

import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.fragment.app.Fragment
import kotlinx.android.synthetic.main.fragment_child.*

class FragmentChild : Fragment(), FragmentListener {

    private lateinit var mFragmentListener: FragmentListener

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        return inflater.inflate(R.layout.fragment_child, container, false)
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        btnChild.setOnClickListener {
            mFragmentListener = parentFragment as FragmentParent
            mFragmentListener.onReceivedData("Child -> Parent")
        }
    }

    override fun onReceivedData(data: String) {
        tvChild.text = data
    }
}

실행 결과

 

 

 

 

 

2. Bundle 객체를 이용하는 방법

 

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="40dp"
    android:paddingRight="40dp"
    android:paddingLeft="40dp"
    android:orientation="vertical"
    android:gravity="center"
    tools:context=".MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:layout_marginBottom="20dp"
        android:textAllCaps="false"
        android:textSize="22dp"
        android:text="MainActivity Area"
        android:textStyle="bold|italic"/>

    <FrameLayout
        android:id="@+id/frameLayoutParent"
        android:layout_width="match_parent"
        android:background="#DDDDDD"
        android:layout_height="0dp"
        android:layout_weight="1"/>

</LinearLayout>

activity_main.xml

 

 

 

fragment_parent.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingLeft="40dp"
    android:paddingRight="40dp"
    android:paddingBottom="40dp"
    android:orientation="vertical"
    android:gravity="center">

    <TextView
        android:id="@+id/tvParent"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:textAllCaps="false"
        android:text="ParentFragment Area"
        android:textSize="20dp"
        android:textStyle="bold|italic"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintBottom_toBottomOf="parent" />

    <Button
        android:id="@+id/btnParent"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:layout_marginBottom="20dp"
        android:textAllCaps="false"
        android:text="Parent -> Child"/>

    <FrameLayout
        android:id="@+id/frameLayoutChild"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="#BBBBBB"/>

</LinearLayout>

fragment_parent.xml

 

 

 

 

fragment_child.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:gravity="top|center">

    <TextView
        android:id="@+id/tvChild"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:textAllCaps="false"
        android:text="ChildFragment Area"
        android:textSize="18dp"
        android:textStyle="bold|italic"/>

    <Button
        android:id="@+id/btnChild"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:textAllCaps="false"
        android:visibility="gone"
        android:text="Child -> Parent"/>

</LinearLayout>

fragment_child.xml

 

 

 

MainActivity.kt

package com.jwsoft.kotlinproject

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        var transaction = supportFragmentManager.beginTransaction()
        transaction.add(R.id.frameLayoutParent, FragmentParent()).commit()
    }

}

 

 

 

 

FragmentParent.kt

package com.jwsoft.kotlinproject

import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.fragment.app.Fragment
import kotlinx.android.synthetic.main.fragment_parent.*

class FragmentParent : Fragment() {

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        return inflater.inflate(R.layout.fragment_parent, container, false)
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        btnParent.setOnClickListener {
            val bundle = Bundle().apply { putString("data", "Parent -> Child") }
            val fragmentChild = FragmentChild().apply { arguments = bundle }
            val transaction = childFragmentManager.beginTransaction()
            transaction.add(R.id.frameLayoutChild, fragmentChild).commit()
        }
    }

}

 

 

 

 

FragmentChild.kt

package com.jwsoft.kotlinproject

import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.fragment.app.Fragment
import kotlinx.android.synthetic.main.fragment_child.*

class FragmentChild : Fragment() {

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        return inflater.inflate(R.layout.fragment_child, container, false)
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        val bundle = arguments
        tvChild.text = bundle!!.getString("data")
    }

}

실행 결과

 

 

 

 

 

3. requireActivity()를 전달인자로 사용한 ViewModel을 공유하는 방법

 

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="40dp"
    android:paddingRight="40dp"
    android:paddingLeft="40dp"
    android:orientation="vertical"
    android:gravity="center"
    tools:context=".MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:layout_marginBottom="20dp"
        android:textAllCaps="false"
        android:textSize="22dp"
        android:text="MainActivity Area"
        android:textStyle="bold|italic"/>

    <FrameLayout
        android:id="@+id/frameLayoutParent"
        android:layout_width="match_parent"
        android:background="#DDDDDD"
        android:layout_height="0dp"
        android:layout_weight="1"/>

</LinearLayout>

activity_main.xml

 

 

 

fragment_parent.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingLeft="40dp"
    android:paddingRight="40dp"
    android:paddingBottom="40dp"
    android:orientation="vertical"
    android:gravity="center">

    <TextView
        android:id="@+id/tvParent"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:textAllCaps="false"
        android:text="ParentFragment Area"
        android:textSize="20dp"
        android:textStyle="bold|italic"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintBottom_toBottomOf="parent" />

    <Button
        android:id="@+id/btnParent"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:layout_marginBottom="20dp"
        android:textAllCaps="false"
        android:text="Parent -> Child"/>

    <FrameLayout
        android:id="@+id/frameLayoutChild"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="#BBBBBB"/>

</LinearLayout>

fragment_parent.xml

 

 

 

fragment_child.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:gravity="top|center">

    <TextView
        android:id="@+id/tvChild"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:textAllCaps="false"
        android:text="ChildFragment Area"
        android:textSize="18dp"
        android:textStyle="bold|italic"/>

    <Button
        android:id="@+id/btnChild"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:textAllCaps="false"
        android:text="Child -> Parent"/>

</LinearLayout>

fragment_child.xml

 

 

 

ActivityViewModel.kt

package com.jwsoft.kotlinproject

import androidx.lifecycle.MutableLiveData
import androidx.lifecycle.ViewModel

class ActivityViewModel : ViewModel() {

    var fragmnetParentText: MutableLiveData<String> = MutableLiveData()
    var fragmentchildText: MutableLiveData<String> = MutableLiveData()

}

 

 

 

 

MainActivity.kt

package com.jwsoft.kotlinproject

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        var transaction = supportFragmentManager.beginTransaction()
        transaction.add(R.id.frameLayoutParent, FragmentParent()).commit()
    }

}

 

 

 

 

FragmentParent.kt

package com.jwsoft.kotlinproject

import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.fragment.app.Fragment
import androidx.lifecycle.Observer
import androidx.lifecycle.ViewModelProvider
import kotlinx.android.synthetic.main.fragment_parent.*

class FragmentParent : Fragment() {

    private lateinit var viewModel: ActivityViewModel

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        viewModel = ViewModelProvider(requireActivity(), ViewModelProvider.NewInstanceFactory())
            .get(ActivityViewModel::class.java)

        return inflater.inflate(R.layout.fragment_parent, container, false)
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        val transaction = fragmentManager!!.beginTransaction()
        transaction.add(R.id.frameLayoutChild, FragmentChild()).commit()

        btnParent.setOnClickListener {
            viewModel.fragmentchildText.value = "Parent -> Child"
        }

        viewModel.fragmnetParentText.observe(this, Observer {
            tvParent.text = it
        })

    }

}

 

 

 

 

FragmentChild.kt

package com.jwsoft.kotlinproject

import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.fragment.app.Fragment
import androidx.lifecycle.Observer
import androidx.lifecycle.ViewModelProvider
import kotlinx.android.synthetic.main.fragment_child.*

class FragmentChild : Fragment() {

    private lateinit var viewModel: ActivityViewModel

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        viewModel = ViewModelProvider(requireActivity(), ViewModelProvider.NewInstanceFactory())
            .get(ActivityViewModel::class.java)

        return inflater.inflate(R.layout.fragment_child, container, false)
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        btnChild.setOnClickListener {
            viewModel.fragmnetParentText.value = "Child -> Parent"
        }

        viewModel.fragmentchildText.observe(this, Observer {
            tvChild.text = it
        })
    }

}

실행 결과

 

 

 

 

 

4. requireParentFragment()를 전달인자로 사용한 ViewModel을 공유하는 방법

 

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="40dp"
    android:paddingRight="40dp"
    android:paddingLeft="40dp"
    android:orientation="vertical"
    android:gravity="center"
    tools:context=".MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:layout_marginBottom="20dp"
        android:textAllCaps="false"
        android:textSize="22dp"
        android:text="MainActivity Area"
        android:textStyle="bold|italic"/>

    <FrameLayout
        android:id="@+id/frameLayoutParent"
        android:layout_width="match_parent"
        android:background="#DDDDDD"
        android:layout_height="0dp"
        android:layout_weight="1"/>

</LinearLayout>

activity_main.xml

 

 

 

fragment_parent.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingLeft="40dp"
    android:paddingRight="40dp"
    android:paddingBottom="40dp"
    android:orientation="vertical"
    android:gravity="center">

    <TextView
        android:id="@+id/tvParent"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:textAllCaps="false"
        android:text="ParentFragment Area"
        android:textSize="20dp"
        android:textStyle="bold|italic"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintBottom_toBottomOf="parent" />

    <Button
        android:id="@+id/btnParent"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:layout_marginBottom="20dp"
        android:textAllCaps="false"
        android:text="Parent -> Child"/>

    <FrameLayout
        android:id="@+id/frameLayoutChild"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="#BBBBBB"/>

</LinearLayout>

fragment_parent.xml

 

 

 

fragment_child.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:gravity="top|center">

    <TextView
        android:id="@+id/tvChild"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:textAllCaps="false"
        android:text="ChildFragment Area"
        android:textSize="18dp"
        android:textStyle="bold|italic"/>

    <Button
        android:id="@+id/btnChild"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:textAllCaps="false"
        android:text="Child -> Parent"/>

</LinearLayout>

fragment_child.xml

 

 

 

FragmentViewModel.kt

package com.jwsoft.kotlinproject

import androidx.lifecycle.MutableLiveData
import androidx.lifecycle.ViewModel

class FragmentViewModel : ViewModel() {

    var fragmnetParentText: MutableLiveData<String> = MutableLiveData()
    var fragmentchildText: MutableLiveData<String> = MutableLiveData()

}

 

 

 

 

MainActivity.kt

package com.jwsoft.kotlinproject

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        var transaction = supportFragmentManager.beginTransaction()
        transaction.add(R.id.frameLayoutParent, FragmentParent()).commit()
    }

}

 

 

 

 

FragmentParent.kt

package com.jwsoft.kotlinproject

import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.fragment.app.Fragment
import androidx.lifecycle.Observer
import androidx.lifecycle.ViewModelProvider
import kotlinx.android.synthetic.main.fragment_parent.*

class FragmentParent : Fragment() {

    private lateinit var viewModel: FragmentViewModel

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        viewModel = ViewModelProvider(this, ViewModelProvider.NewInstanceFactory())
            .get(FragmentViewModel::class.java)

        return inflater.inflate(R.layout.fragment_parent, container, false)
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        // fragmentManager 사용하면 안됨
        val transaction = childFragmentManager.beginTransaction()
        transaction.add(R.id.frameLayoutChild, FragmentChild()).commit()

        btnParent.setOnClickListener {
            viewModel.fragmentchildText.value = "Parent -> Child"
        }

        viewModel.fragmnetParentText.observe(this, Observer {
            tvParent.text = it
        })

    }

}

val transaction = fragmentManager!!.beginTransaction() -> X

val transaction = childFragmentManager.beginTransaction() -> O

 

 

 

 

FragmentChild.kt

package com.jwsoft.kotlinproject

import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.fragment.app.Fragment
import androidx.lifecycle.Observer
import androidx.lifecycle.ViewModelProvider
import kotlinx.android.synthetic.main.fragment_child.*

class FragmentChild : Fragment() {

    private lateinit var viewModel: FragmentViewModel

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        viewModel = ViewModelProvider(requireParentFragment(), ViewModelProvider.NewInstanceFactory())
            .get(FragmentViewModel::class.java)

        return inflater.inflate(R.layout.fragment_child, container, false)
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        btnChild.setOnClickListener {
            viewModel.fragmnetParentText.value = "Child -> Parent"
        }

        viewModel.fragmentchildText.observe(this, Observer {
            tvChild.text = it
        })
    }

}

 

requireParentFragment() 사용

 

실행 결과

 

 

 

 

 

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