簡單使用

• 演示圖
  

步驟：

1. 創建menu文件
2. 根據menu創建對應的Fragment
3. 在主佈局創建Bottom Navigation和Fragment Container
4. 在主畫面註冊導航欄的點擊事件、切換頁面等程式碼

Step 1

創建menu資源文件

• res > New > Android Resource Directory
  

• 下一步
  

• 創建bottom_navigation.xml

  <?xml version="1.0" encoding="utf-8"?>
  <menu xmlns:android="http://schemas.android.com/apk/res/android">
      <item
          android:id="@+id/nav_home"
          android:icon="@drawable/ic_home_24"
          android:title="首頁" />
  
      <item
          android:id="@+id/nav_store"
          android:icon="@drawable/ic_store_24"
          android:title="商店"
          />
  
      <item
          android:id="@+id/nav_account"
          android:icon="@drawable/ic_account_24"
          android:title="帳號" />
  </menu>
  

Step 2

根據menu創建對應的Fragment

Step 3

在主佈局創建Bottom Navigation和Fragment Container控件

• 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=".MainActivity">
  
      <androidx.fragment.app.FragmentContainerView
          android:id="@+id/fragment_container"
          android:name="com.example.itbottomnavigationdemo1.HomeFragment"
          android:layout_width="0dp"
          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_toTopOf="parent"
          app:layout_constraintVertical_bias="0.0" />
  
      <com.google.android.material.bottomnavigation.BottomNavigationView
          android:id="@+id/bottom_nav"
          android:background="#ddd"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          app:layout_constraintBottom_toBottomOf="parent"
          app:layout_constraintEnd_toEndOf="parent"
          app:layout_constraintStart_toStartOf="parent"
          app:menu="@menu/bottom_navigation">
      </com.google.android.material.bottomnavigation.BottomNavigationView>
  
  </androidx.constraintlayout.widget.ConstraintLayout>
  

Step 4

在主畫面註冊導航欄的點擊事件、切換頁面等程式碼

• MainActivity

public class MainActivity extends AppCompatActivity {
    ...
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        binding = ActivityMainBinding.inflate(getLayoutInflater());
        setContentView(binding.getRoot());

        // 註冊底部導航欄按鈕選擇事件
        binding.bottomNav.setOnItemSelectedListener(new NavigationBarView.OnItemSelectedListener() {
            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem item) {
                Fragment selectFragment = null;
                switch (item.getItemId()) {
                    case R.id.nav_home:
                        selectFragment = new HomeFragment();
                        break;
                    case R.id.nav_store:
                        selectFragment = new StoreFragment();
                        break;
                    case R.id.nav_account:
                        selectFragment = new AccountFragment();
                        break;
                    default: break;
                }
                getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, selectFragment).commit();
                return true;
            }
        });
    }
}