android - Tapbar ( fragment )

1. implement

implementation 'androidx.navigation:navigation-fragment:2.5.3'
implementation 'androidx.navigation:navigation-ui:2.5.3'

 

2. ui 

// activation_main

<com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/bottomNavigationView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:background="#fff"
        app:itemIconSize="30dp"
        app:labelVisibilityMode="selected"
        app:menu="@menu/bottom_menu">

    </com.google.android.material.bottomnavigation.BottomNavigationView>

    <androidx.fragment.app.FragmentContainerView
        android:id="@+id/fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_above="@id/bottomNavigationView"
        app:defaultNavHost="true"
        app:navGraph="@navigation/my_nav" />

//navigation 폴더에  my_nav
<navigation 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:id="@+id/my_nav"
    app:startDestination="@id/firstFragment">

    <fragment
        android:id="@+id/firstFragment"
        android:name="com.rrc0777.tabbar.FirstFragment"
        android:label="fragment_first"
        tools:layout="@layout/fragment_first" />
    <fragment
        android:id="@+id/secondFragment"
        android:name="com.rrc0777.tabbar.SecondFragment"
        android:label="fragment_second"
        tools:layout="@layout/fragment_second" />
    <fragment
        android:id="@+id/thirdFragment"
        android:name="com.rrc0777.tabbar.ThirdFragment"
        android:label="fragment_third"
        tools:layout="@layout/fragment_third" />
</navigation>

 

3. java code

// main

// 멤버변수
 BottomNavigationView navigationView;
 Fragment firstFragment;
 Fragment secondFragment;
 Fragment thirdFragment;

// onCreate
navigationView = findViewById(R.id.bottomNavigationView);
firstFragment = new FirstFragment();
secondFragment = new SecondFragment();
thirdFragment = new ThirdFragment();

navigationView.setOnItemSelectedListener(new NavigationBarView.OnItemSelectedListener() {
            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem item) {
                int itemId = item.getItemId();

                Fragment fragment;

                if(itemId == R.id.firstFragment){
                    fragment = firstFragment;
                    
                }else if(itemId == R.id.secondFragment){
                    fragment = secondFragment;
                   
                }else{
                    fragment = thirdFragment;
                    
                }
                return loadFragment(fragment);
            }
        });

        //
    }
 // loadfragment 메소드
 private boolean loadFragment(Fragment fragment){
        if(fragment != null){
            getSupportFragmentManager()
                    .beginTransaction()
                    .replace(R.id.fragment,fragment)
                    .commit();
            return true;
        }
        else{
            return false;
        }
    }

// FirstFlagment 는 다음과 같이 되어있다.
public class FirstFragment extends Fragment {

    // TODO: Rename parameter arguments, choose names that match
    // the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
    private static final String ARG_PARAM1 = "param1";
    private static final String ARG_PARAM2 = "param2";

    // TODO: Rename and change types of parameters
    private String mParam1;
    private String mParam2;

    public FirstFragment() {
        // Required empty public constructor
    }

    /**
     * Use this factory method to create a new instance of
     * this fragment using the provided parameters.
     *
     * @param param1 Parameter 1.
     * @param param2 Parameter 2.
     * @return A new instance of fragment FirstFragment.
     */
    // TODO: Rename and change types and number of parameters
    public static FirstFragment newInstance(String param1, String param2) {
        FirstFragment fragment = new FirstFragment();
        Bundle args = new Bundle();
        args.putString(ARG_PARAM1, param1);
        args.putString(ARG_PARAM2, param2);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            mParam1 = getArguments().getString(ARG_PARAM1);
            mParam2 = getArguments().getString(ARG_PARAM2);
        }
    }

    // 화면 관련 logic 은 onCreateView 에서 처리한다.
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        
        return new inflater.inflate(R.layout.fragment_first, container, false);
    }