[Android/Kotlin] fragment특징과 생명주기(lifecycle) + 예제

 

fragment

-부분화면이면서 액티비티처럼 독립적으로 동작함

-액티비티 위에 올라와야 정상적인 프래그먼트로 동작함

-Activity처럼 life cycle이 존재

-프래그먼트 매니저에 의해 관리됨

 

프래그먼트의 생명주기(Lifecycle)

1. 액티비티에 프래그먼트 추가

onAttach() -> onCreate() -> onCreateView() -> onActivityCreated() -> onStart() -> onResume() -> 프래그먼트 활성화

2. 액티비티에서 프래그먼트 제거

프래그먼트 활성화 -> onPause() -> onStop() -> onDestroyView() -> onDestroy() -> onDetach()

 

 

 

 

 

 

 

+예제

로그인/메뉴 화면을 fragment로 만들어보자!

 

package com.mobile.fragment

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

class LoginFragment : Fragment() {

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
        val rootView = inflater.inflate(R.layout.fragment_login, container, false)

        rootView.nextButton.setOnClickListener{
            val mainActivity = activity as MainActivity
            mainActivity.onFragmentChanged(1)
        }
        return rootView
    }

    }

package com.mobile.fragment

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {
    var loginFragment:LoginFragment = LoginFragment()
    var menuFragment:MenuFragment = MenuFragment()

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

        showLoginButton.setOnClickListener{
            //supportFragmentManager.beginTransaction().replace(R.id.container, LoginFragment()).commit()
//            with(supportFragmentManager.beginTransaction()){
//                replace(R.id.container, loginFragment)
//            }.commit()
            onFragmentChanged(0)
        }

        showMenuButton.setOnClickListener{
            //supportFragmentManager.beginTransaction().replace(R.id.container, MenuFragment()).commit()
//            with(supportFragmentManager.beginTransaction()){
//                replace(R.id.container, menuFragment)
//            }.commit()
            onFragmentChanged(1)
        }
    }

    fun onFragmentChanged(index:Int){
        when(index){
            0 -> {
                with(supportFragmentManager.beginTransaction()){
                    replace(R.id.container, loginFragment)
                }.commit()
            }
            1 -> {
                with(supportFragmentManager.beginTransaction()){
                    replace(R.id.container, menuFragment)
                }.commit()
            }
        }

    }
}

package com.mobile.fragment

import android.os.Bundle
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
class MenuFragment : Fragment() {

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_menu, container, false)
    }

    }

<?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">

    <Button
        android:id="@+id/showLoginButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="14dp"
        android:layout_marginTop="10dp"
        android:text="로그인"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <FrameLayout
        android:id="@+id/container"
        android:layout_width="409dp"
        android:layout_height="671dp"
        android:layout_marginStart="1dp"
        android:layout_marginTop="5dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/showLoginButton">


        <androidx.fragment.app.FragmentContainerView
            android:id="@+id/fragmentContainerView2"
            android:name="com.mobile.fragment.LoginFragment"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />
    </FrameLayout>

    <Button
        android:id="@+id/showMenuButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="28dp"
        android:layout_marginTop="10dp"
        android:text="메뉴"
        app:layout_constraintStart_toEndOf="@+id/showLoginButton"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

<?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:id="@+id/loginFragment"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#FBD5D5"
    android:orientation="vertical"
    tools:context=".LoginFragment">

    <TextView
        android:id="@+id/textView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="로그인 화면"
        android:textSize="40sp" />

    <EditText
        android:id="@+id/editTextTextPersonName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10"
        android:inputType="textPersonName" />

    <Button
        android:id="@+id/nextButton"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="다음으로" />
</LinearLayout>

<?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:id="@+id/loginFragment"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#DCECF3"
    android:orientation="vertical"
    tools:context=".LoginFragment">

    <TextView
        android:id="@+id/textView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="메뉴 화면"
        android:textSize="40sp" />

    <EditText
        android:id="@+id/editTextTextPersonName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10"
        android:inputType="textPersonName" />

    <Button
        android:id="@+id/nextButton"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Button" />
</LinearLayout>