BottomNavigation , ViewPager

.kt

FirstFragment.kt

package com.example.imagesearchapp.ui.fragment

import android.os.Bundle
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.Button
import com.example.imagesearchapp.R
import com.example.imagesearchapp.databinding.FragmentFirstBinding




    class FirstFragment : Fragment() {
        private lateinit var binding : FragmentFirstBinding

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


    }
    

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SecondFragment.kt

package com.example.imagesearchapp.ui.fragment

import android.os.Bundle
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import com.example.imagesearchapp.databinding.FragmentSecondBinding


class SecondFragment : Fragment() {
    private lateinit var binding: FragmentSecondBinding

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

---

MainActivity.kt

package com.example.imagesearchapp.ui.activity

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import androidx.viewpager2.widget.ViewPager2
import com.example.imagesearchapp.R
import com.example.imagesearchapp.databinding.ActivityMainBinding
import com.example.imagesearchapp.ui.adapter.ViewPagerAdapter

// TabLayout , ViewPager2 연동

class MainActivity : AppCompatActivity() {

    private lateinit var binding: ActivityMainBinding

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

        //viewBinding
        binding = ActivityMainBinding.inflate(layoutInflater)
        val view = binding.root
        setContentView(view)

        initViewPager()
        initNavigation()

    }

    private fun initViewPager() {
        val viewPager = binding.viewPager
        val viewPagerAdapter = ViewPagerAdapter(supportFragmentManager, lifecycle)

        //page에 adapter 연결
        viewPager.adapter = viewPagerAdapter

        //ViewPager 로 슬라이드 시, BottomNavigation 도 페이지 활성화
        viewPager.registerOnPageChangeCallback(object : ViewPager2.OnPageChangeCallback() {
            override fun onPageSelected(position: Int) {
                super.onPageSelected(position)
                binding.bottomNavigation.menu.getItem(position).isChecked = true
            }
        })

    }

    // 앱의 네비게이션 로직을 초기화하고 항목을 클릭했을 때, 해당 프래그먼트로 이동 (initNavigation)
    //BottomNavigation의 선택된 메뉴의 리스너를 설정 (OnNavigationItemSelected)(권장)
    private fun initNavigation() {

        binding.bottomNavigation.setOnItemSelectedListener {
            when (it.itemId) { ////////////////////////////////////////////////////////////클릭된 아이템의 식별자 나타냄
                R.id.search -> {
                    binding.viewPager.currentItem = 0
                    true
                }

                R.id.storage -> {
                    binding.viewPager.currentItem = 1
                    true
                }

                else -> false
            }
        }
    }
}

---

.xml

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=".ui.activity.MainActivity">

    <androidx.viewpager2.widget.ViewPager2
        android:id="@+id/viewPager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_constraintStart_toStartOf="parent" />

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/bottomNavigation"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#B7185A1B"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/recyclerView"
        app:layout_constraintVertical_bias="1.0"
        app:menu="@menu/item_menu_navi" />


</androidx.constraintlayout.widget.ConstraintLayout>


    <!--    [app:labelVisibilityMode]-->
    <!--    auto : 항목이 3개 이하일 경우 속성이 labeled, 4개 이상일 경우 selected-->
    <!--    labeled : 텍스트 항상 표시-->
    <!--    selected : 아이템이 선택 되었을 때만 텍스트 표시-->
    <!--    unlabeled : 텍스트 표시하지 않음-->
    

---

fragment_first.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout 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:orientation="vertical"
    tools:context=".ui.fragment.FirstFragment">

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">


        <com.google.android.material.card.MaterialCardView
            android:layout_width="match_parent"
            android:layout_height="70dp"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent">

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="70dp"
                android:orientation="horizontal"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toTopOf="parent">

                <!--     빈공간 없이 꽉 채우기-->
                <EditText
                    android:id="@+id/search_bar"
                    android:layout_width="0dp"
                    android:layout_height="39dp"
                    android:layout_marginStart="20dp"
                    android:layout_marginTop="16dp"
                    android:layout_weight="1"
                    android:background="@drawable/border"
                    android:hint="검색 창"
                    android:textSize="20sp"
                    app:layout_constraintTop_toTopOf="parent"
                    tools:layout_editor_absoluteX="31dp" />

                <Button
                    android:id="@+id/search_btn"
                    android:layout_width="80dp"
                    android:layout_height="39dp"
                    android:layout_marginStart="10dp"
                    android:layout_marginTop="16dp"
                    android:layout_marginEnd="16dp"
                    android:background="#28652B"
                    android:text="검색" />

            </LinearLayout>
        </com.google.android.material.card.MaterialCardView>


        <!--Floating_Action_Button-->

        <com.google.android.material.floatingactionbutton.FloatingActionButton
            android:id="@+id/btn_toTop"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginEnd="20dp"
            android:layout_marginBottom="100dp"
            android:src="@drawable/goup_icon"
            app:backgroundTint="#B7CCA6"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent" />


    </androidx.constraintlayout.widget.ConstraintLayout>

</FrameLayout>

---

fragment_second.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout 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=".ui.fragment.SecondFragment">

    <!-- TODO: Update blank fragment layout -->
    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="second fragment" />

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:contentDescription="test"
        android:src="@drawable/photo" />

</FrameLayout>

---

Adapter

ViewPagerAdapter

package com.example.imagesearchapp.ui.adapter

import androidx.fragment.app.Fragment
import androidx.fragment.app.FragmentManager
import androidx.lifecycle.Lifecycle
import androidx.viewpager2.adapter.FragmentStateAdapter
import com.example.imagesearchapp.ui.fragment.FirstFragment
import com.example.imagesearchapp.ui.fragment.SecondFragment

private const val NUM_TABS = 2
class ViewPagerAdapter(fragmentManager: FragmentManager, lifecycle: Lifecycle) :
    FragmentStateAdapter(fragmentManager, lifecycle) {

    override fun getItemCount(): Int {
        return NUM_TABS
    }

    override fun createFragment(position: Int): Fragment {
        when (position) {
            0 -> return FirstFragment()
            1 -> return SecondFragment()
        }
        return SecondFragment()
    }
}

//어떤 Tab을 눌렀을 때, 어떤 Fragment가 생성되어야 하는지 구체적인 내용 구현

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