Android底部导航组件BottomNavigationView

什么是BottomNavigationView

底部菜单栏

BottomNavigationView的简单用法

需求：如上图所示。点击测试一菜单，展示test1fragment。点击测试二菜单，展示test2fragment。点击测试三菜单，展示test3fragment。

第一步，testActivity布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:app="http://schemas.android.com/apk/res-auto"
 android:id="@+id/container"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:orientation="vertical">
 // 容器，承载fragment
 <FrameLayout
   android:id="@+id/nav_host_fragment"
   android:name="androidx.navigation.fragment.NavHostFragment"
   android:layout_width="match_parent"
   android:layout_height="0dp"
   android:layout_weight="1" />
 // BottomNavigationView
 <com.google.android.material.bottomnavigation.BottomNavigationView
   android:id="@+id/nav_view"
   android:layout_width="match_parent"
   android:layout_height="wrap_content"
   android:background="?android:attr/windowBackground"
   app:menu="@menu/bottom_nav_menu_test" />
</LinearLayout>

第二步，写BottomNavigationView所需要的菜单

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
 <item
   android:id="@+id/navigation_test1"
   android:icon="@drawable/ic_home_black_24dp"
   android:title="测试一" />
 <item
   android:id="@+id/navigation_test2"
   android:icon="@drawable/ic_dashboard_black_24dp"
   android:title="测试二" />
 <item
   android:id="@+id/navigation_test3"
   android:icon="@drawable/ic_notifications_black_24dp"
   android:title="测试三" />
</menu>

第三步，书写testActivity文件。重点是setOnNavigationItemSelectedListener点击事件

public class TestActivity extends AppCompatActivity {
 List<Fragment> mFragments = new ArrayList<>();
 test1Fragment t1f = new test1Fragment();
 test2Fragment t2f = new test2Fragment();
 test3Fragment t3f = new test3Fragment();
 @Override
 protected void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.activity_test);
   BottomNavigationView navView = findViewById(R.id.nav_view);
   mFragments.add(t1f);
   mFragments.add(t2f);
   mFragments.add(t3f);
   // navView 点击事件
   navView.setOnNavigationItemSelectedListener((item)->{
     switchFragment(item.getItemId());
     return true;
   });
 }
 private void switchFragment(int id) {
   Fragment fragment = null;
   switch (id) {
     case R.id.navigation_test1:
       fragment = mFragments.get(0);
       break;
     case R.id.navigation_test2:
       fragment = mFragments.get(1);
       break;
     case R.id.navigation_test3:
       fragment = mFragments.get(2);
       break;
     default:
       break;
   }
   if (fragment != null) {
     getSupportFragmentManager().beginTransaction().replace(R.id.nav_host_fragment,fragment).commit();
   }
 }
}

来源：https://feilx.blog.csdn.net/article/details/129489371