[Kotlin] Fragment 간의 데이터 전달

1. Interface를 이용하는 방법

2. ViewModel을 공유하는 방법

---

1. Interface를 이용하는 방법

 

fragment_red.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"
    android:background="#FFBBBB">

    <TextView
        android:id="@+id/tvRed"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="24dp"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"
        tools:text="Red"/>

    <Button
        android:id="@+id/btnSendToGreen"
        android:layout_width="200dp"
        android:layout_height="60dp"
        android:layout_marginTop="20dp"
        android:textAllCaps="false"
        android:text="Send To Green"
        android:textSize="24dp"
        app:layout_constraintTop_toBottomOf="@+id/tvRed"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"/>

</androidx.constraintlayout.widget.ConstraintLayout>

fragment_red.xml

 

 

 

fragment_green.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"
    android:background="#BBFFBB">

    <TextView
        android:id="@+id/tvGreen"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="24dp"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"
        tools:text="Green"/>

    <Button
        android:id="@+id/btnSendToRed"
        android:layout_width="200dp"
        android:layout_height="60dp"
        android:layout_marginTop="20dp"
        android:textAllCaps="false"
        android:text="Send To Red"
        android:textSize="24dp"
        app:layout_constraintTop_toBottomOf="@+id/tvGreen"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"/>

</androidx.constraintlayout.widget.ConstraintLayout>

fragment_green.xml

 

 

 

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:orientation="vertical"
    android:gravity="center"
    tools:context=".MainActivity">

    <FrameLayout
        android:id="@+id/frameLayoutRed"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"/>

    <FrameLayout
        android:id="@+id/frameLayoutGreen"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"/>

</LinearLayout>

activity_main.xml

 

 

 

FragmentListener.kt

package com.jwsoft.kotlinproject

interface FragmentListener {
    fun onReceivedData(data: String, fragment: String)
}

 

 

 

 

FragmentRed.kt

package com.jwsoft.kotlinproject

import android.content.Context
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_red.*

class FragmentRed : Fragment() {

    private lateinit var mFragmentListener: FragmentListener

    override fun onAttach(context: Context) {
        super.onAttach(context)
        mFragmentListener = activity as FragmentListener
    }

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

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

        btnSendToGreen.setOnClickListener {
            mFragmentListener.onReceivedData("Red -> Green", "Red")
        }
    }

    fun setText(text: String) {
        tvRed.text = text
    }

}

 

 

 

 

 

FragmentGreen.kt

package com.jwsoft.kotlinproject

import android.content.Context
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_green.*

class FragmentGreen : Fragment() {

    private lateinit var mFragmentListener: FragmentListener

    override fun onAttach(context: Context) {
        super.onAttach(context)
        mFragmentListener = activity as FragmentListener
    }

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

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

        btnSendToRed.setOnClickListener {
            mFragmentListener.onReceivedData("Green -> Red", "Green")
        }
    }

    fun setText(text: String) {
        tvGreen.text = text
    }

}

 

 

 

 

MainActivity.kt

package com.jwsoft.kotlinproject

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

class MainActivity : AppCompatActivity(), FragmentListener {

    private val fragmentRed = FragmentRed()
    private val fragmentGreen = FragmentGreen()

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

        var transactionRed = supportFragmentManager.beginTransaction()
        transactionRed.add(R.id.frameLayoutRed, fragmentRed).commit()

        var transactionGreen = supportFragmentManager.beginTransaction()
        transactionGreen.add(R.id.frameLayoutGreen, fragmentGreen).commit()

    }

    override fun onReceivedData(data: String, fragment: String) {
        if (fragment == "Red") {
            fragmentGreen.setText(data)
        } else {
            fragmentRed.setText(data)
        }
    }
}

실행 결과

 

 

 

 

---

2. ViewModel을 공유하는 방법

 

fragment_red.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"
    android:background="#FFBBBB">

    <TextView
        android:id="@+id/tvRed"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="24dp"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"
        tools:text="Red"/>

    <Button
        android:id="@+id/btnRed"
        android:layout_width="200dp"
        android:layout_height="60dp"
        android:layout_marginTop="20dp"
        android:textAllCaps="false"
        android:text="Send To Green"
        android:textSize="24dp"
        app:layout_constraintTop_toBottomOf="@+id/tvRed"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"/>

</androidx.constraintlayout.widget.ConstraintLayout>

 

 

 

 

fragment_green.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"
    android:background="#BBFFBB">

    <TextView
        android:id="@+id/tvGreen"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="24dp"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"
        tools:text="Green"/>

    <Button
        android:id="@+id/btnGreen"
        android:layout_width="200dp"
        android:layout_height="60dp"
        android:layout_marginTop="20dp"
        android:textAllCaps="false"
        android:text="Send To Red"
        android:textSize="24dp"
        app:layout_constraintTop_toBottomOf="@+id/tvGreen"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"/>

</androidx.constraintlayout.widget.ConstraintLayout>

 

 

 

 

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:orientation="vertical"
    android:gravity="center"
    tools:context=".MainActivity">

    <FrameLayout
        android:id="@+id/frameLayoutRed"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"/>

    <FrameLayout
        android:id="@+id/frameLayoutGreen"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"/>

</LinearLayout>

 

 

 

 

ActivityViewModel.kt

package com.jwsoft.kotlinproject

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

class ActivityViewModel : ViewModel() {

    var fragmentRedText: MutableLiveData<String> = MutableLiveData()
    var fragmentGreenText: MutableLiveData<String> = MutableLiveData()

}

 

 

 

 

FragmentRed.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_red.*

class FragmentRed : 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_red, container, false)
    }

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

        viewModel.fragmentRedText.observe(this, Observer {
            tvRed.text = it
        })

        btnRed.setOnClickListener {
            viewModel.fragmentGreenText.value = "Red -> Green"
        }
    }

}

 

 

 

 

FragmentGreen.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_green.*

class FragmentGreen : 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_green, container, false)
    }

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

        viewModel.fragmentGreenText.observe(this, Observer {
            tvGreen.text = it
        })

        btnGreen.setOnClickListener {
            viewModel.fragmentRedText.value = "Green -> Red"
        }
    }

}

 

 

 

 

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 transactionRed = supportFragmentManager.beginTransaction()
        transactionRed.add(R.id.frameLayoutRed, FragmentRed()).commit()

        var transactionGreen = supportFragmentManager.beginTransaction()
        transactionGreen.add(R.id.frameLayoutGreen, FragmentGreen()).commit()
    }

}

실행 결과