本篇主要介绍使用2个以上的tab页时的实现；
- 接着上篇建立的FirstFragment.java, SecondFragment.java
- 导航视图文件nav_fragment.xml修改成：
<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"
app:startDestination="@id/firstFragment">
<fragment
android:id="@+id/firstFragment"
android:name="com.example.jatpack.navigation.FirstFragment"
android:label="fragment_first"
tools:layout="@layout/fragment_first" >
<action
android:id="@+id/action_firstFragment_to_second"
app:destination="@id/secondFragment" />
<action
android:id="@+id/action_firstFragment_to_food"
app:destination="@id/foodFragment" />
</fragment>
<fragment
android:id="@+id/secondFragment"
android:name="com.example.jatpack.navigation.SecondFragment"
android:label="fragment_second"
tools:layout="@layout/fragment_second" >
<action
android:id="@+id/action_firstFragment_to_second"
app:destination="@id/firstFragment" />
<action
android:id="@+id/action_firstFragment_to_food"
app:destination="@id/foodFragment" />
</fragment>
<fragment
android:id="@+id/foodFragment"
android:name="com.example.jatpack.navigation.FoodFragment"
android:label="fragment_food"
tools:layout="@layout/fragment_food" >
<action
android:id="@+id/action_foodFragment_to_first"
app:destination="@id/firstFragment" />
<action
android:id="@+id/action_foodFragment_to_second"
app:destination="@id/secondFragment" />
</fragment>
</navigation>
- 在res下新建menu文件夹，并新建menu_navigation.xml
<menu xmlns:android="http://schemas.android.com/apk/res/android">
<item
android:id="@+id/menu_fragment1"
android:icon="@drawable/bottom_sel"
android:title="firstFragment"/>
<item
android:id="@+id/menu_fragment2"
android:icon="@drawable/bottom_sel"
android:title="secondFragment"/>
<item
android:id="@+id/menu_food"
android:icon="@drawable/bottom_sel"
android:title="foodFragment"/>
</menu>
bottom_sel.xml 切换icon的状态，选中与非选中时呈现不一样的图片：
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:state_checked="true" android:drawable="@drawable/ic_launcher_round"/>
<item android:state_checked="false" android:drawable="@drawable/ic_launcher"/>
</selector>
- MainActivity.java
public class MainActivity extends AppCompatActivity implements BottomNavigationView.OnNavigationItemSelectedListener {
private NavigationController navController;
private BottomNavigationView bottomNavView;
private MenuItem menuItem;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initNav();
}
private void initNav(){
navController = Navigation.findNavController(this,R.id.fragment);
bottomNavView = (BottomNavigationView) findViewById(R.id.bottomnavigationview);
NavigationUI.setupWithNavController(bottomNavView,navController );
bottomeNavView.setItemIconTintList(null);
bottomNavView.setOnNavigationItemSelectedListener(this);
}
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
int itemId = item.getItemId();
switch (itemId){
case R.id.menu_fragment1:
//当该项已经被选中时，不执行任何操作
if(item.isChecked()) {
return true;
}
if (bottomNavView.getSelectedItemId() == R.id.menu_fragment2) {
navController.navigate(R.id.action_secondFragment_to_first);
} else if ((bottomNavView.getSelectedItemId() == R.id.menu_food) {
navController.navigate(R.id.action_foodFragment_to_first);
}
menuItem.setChecked(true);
break;
case R.id.menu_fragment2:
if(item.isChecked()) {
return true;
}
if (bottomNavView.getSelectedItemId() == R.id.menu_fragment1) {
navController.navigate(R.id.action_firstFragment_to_second);
} else if ((bottomNavView.getSelectedItemId() == R.id.menu_food) {
navController.navigate(R.id.action_foodFragment_to_second);
}
menuItem.setChecked(true);
break;
case R.id.menu_food:
if(item.isChecked()) {
return true;
}
if (bottomNavView.getSelectedItemId() == R.id.menu_fragment1) {
navController.navigate(R.id.action_firstFragment_to_food);
} else if ((bottomNavView.getSelectedItemId() == R.id.menu_fragment2) {
navController.navigate(R.id.action_secondFragment_to_food);
}
menuItem.setChecked(true);
break;
}
return false;
}
}
- 布局文件
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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">
<fragment
android:name="androidx.navigation.fragment.NavHostFragment"
android:id="@+id/fragment"
android:layout_above="@+id/bottomnavview"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:defaultNavHost="false"
app:navGraph="@navigation/nav_fragment" />
<!--app:itemBackground="@null" 去掉焦点效果-->
<android.support.design.widget.BottomNavigationView
android:id="@+id/bottomnavview"
android:layout_alignParentBottom="true"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:itemBackground="@null"
app:menu="@menu/menu_navigation">
</android.support.design.widget.BottomNavigationView>
</RelativeLayout>
