안드로이드 상단 분리된 메뉴

dependencies {

    implementation 'androidx.appcompat:appcompat:1.2.0'
    implementation 'com.google.android.material:material:1.2.1'
    implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
    implementation 'com.google.android.material:material:1.2.0-alpha01'
    testImplementation 'junit:junit:4.+'
    androidTestImplementation 'androidx.test.ext:junit:1.1.2'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'
}

//implementation 'com.google.android.material:material:1.2.0-alpha01' 추가

// 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">

    <com.google.android.material.tabs.TabLayout
        android:id="@+id/tab_layout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_constraintBottom_toTopOf="@+id/const_vp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">

        <com.google.android.material.tabs.TabItem
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Monday" />

        <com.google.android.material.tabs.TabItem
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Tuesday" />

        <com.google.android.material.tabs.TabItem
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Wednesday" />
    </com.google.android.material.tabs.TabLayout>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:id="@+id/const_vp"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="1.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/tab_layout"
        app:layout_constraintVertical_bias="0.425">

        <androidx.viewpager.widget.ViewPager
            android:id="@+id/viewPager"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />
    </androidx.constraintlayout.widget.ConstraintLayout>

</androidx.constraintlayout.widget.ConstraintLayout>

//fragment 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">

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="다원프로젝트 3"
        android:textSize="30sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

// fragment. class



package com.gohool.viewpager;

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;

public class Fragment1 extends Fragment {

    private View view;


    //fragment가 주기적으로 변경됨에 따라 상태저장이 필요함
    public static Fragment1 newInstance(){
        Fragment1 fragment1 = new Fragment1();
        return fragment1;
    }


    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        view = inflater.inflate(R.layout.fragment1,container,false);

        return view;
    }
}

//adapter . class



package com.gohool.viewpager;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;
import androidx.fragment.app.FragmentPagerAdapter;

public class PagerAdapter extends FragmentPagerAdapter {
    public PagerAdapter(@NonNull FragmentManager fm) {
        super(fm);
    }


//프래그먼트 교체를 보여주는 처리를 구현한 곳
    @NonNull
    @Override
    public Fragment getItem(int position) {
        switch (position){
            case 0:
                return Fragment1.newInstance(); //화면을 띄어주기 위해 어뎁터에서 인식을 할 수 있게
            case 1:
                return Fragment2.newInstance();
            case 2:
                return Fragment3.newInstance();
            default:
                return null;
        }
    }

    //뷰페이지 개수
    @Override
    public int getCount() {
        return 3;
    }

    //각 뷰페이지의 이름
    @Nullable
    @Override
    public CharSequence getPageTitle(int position) {
        switch (position){
            case 0:
                return "Monday";
            case 1:
                return "tuesday";
            case 2:
                return "friday";
            default:
                return null;
        }
    }
}

// main activity . java



package com.gohool.viewpager;

import android.os.Bundle;

import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.FragmentPagerAdapter;
import androidx.viewpager.widget.ViewPager;

import com.google.android.material.tabs.TabLayout;

public class MainActivity extends AppCompatActivity {

    private FragmentPagerAdapter fragmentPagerAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);



        //뷰페이저 세팅
        ViewPager viewPager = findViewById(R.id.viewPager);
        PagerAdapter fragmentPagerAdapter = new PagerAdapter(getSupportFragmentManager());

        TabLayout tabLayout = findViewById(R.id.tab_layout);
        viewPager.setAdapter(fragmentPagerAdapter); //연동
        tabLayout.setupWithViewPager(viewPager);
    }
}