【发布时间】：2021-12-03 18:42:40
【问题描述】：
我正在计划一个 3 页的地图应用程序。我的第一页上有一张地图。每次点击底部导航都会重新加载我的地图。我怎样才能防止这种情况发生？
我的导航图
由于子页面太多，我无法对事务执行此操作。
<?xml version="1.0" encoding="utf-8"?>
<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/nav_graph"
app:startDestination="@id/home">
<include app:graph="@navigation/dashboard" />
<include app:graph="@navigation/home" />
<include app:graph="@navigation/menu" />
</navigation>
我的地图导航图
<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/home"
app:startDestination="@id/homeFragment">
<fragment
android:id="@+id/homeFragment"
android:name="com.example.bottomnavwithnavigationcomponent.homeScreen.HomeFragment"
android:label="Home"
tools:layout="@layout/fragment_home" />
<fragment
android:id="@+id/homeFragment2"
android:name="com.example.bottomnavwithnavigationcomponent.homeScreen.HomeFragment2"
android:label="Home"
tools:layout="@layout/fragment_home2" />
MainActivity
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
BottomNavigationView bottomNavigationView = findViewById(R.id.bottomNavigationView);
NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
NavigationUI.setupWithNavController(bottomNavigationView, navController);
NavigationUI.setupActionBarWithNavController(this, navController);
}
@Override
public boolean onSupportNavigateUp() {
onBackPressed();
return super.onSupportNavigateUp();
}
}
地图片段
此页面上有一个试用片段转换。 我希望这个页面永远不会被刷新。
public class HomeFragment extends Fragment {
private OnMapReadyCallback callback = new OnMapReadyCallback() {
@Override
public void onMapReady(GoogleMap googleMap) {
LatLng sydney = new LatLng(-34, 151);
googleMap.addMarker(new MarkerOptions().position(sydney).title("Marker in Sydney"));
googleMap.moveCamera(CameraUpdateFactory.newLatLng(sydney));
}
};
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater,
@Nullable ViewGroup container,
@Nullable Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_home, container, false);
}
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
SupportMapFragment mapFragment =
(SupportMapFragment) getChildFragmentManager().findFragmentById(R.id.map);
if (mapFragment != null) {
mapFragment.getMapAsync(callback);
}
}
}
我是通过事务处理的，但它非常不正常。
binding.navigationBottom.setOnItemSelectedListener(new BottomNavigationView.OnItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem menuItem) {
if(menuItem.getItemId() == R.id.people){
removeFragment(tempFragment);
}
if(menuItem.getItemId() == R.id.group){
if (tempFragment ==null){
getFragment(groupFragment);
}
else {
removeFragment(tempFragment);
getFragment(groupFragment);
}
tempFragment = groupFragment;
}
if(menuItem.getItemId() == R.id.places){
if (tempFragment ==null){
getFragment(addFragment);
}
else {
removeFragment(tempFragment);
getFragment(addFragment);
}
tempFragment = addFragment;
}
if(menuItem.getItemId() == R.id.blank){
if (tempFragment ==null){
getFragment(blankFragment);
}
else {
removeFragment(tempFragment);
getFragment(blankFragment);
}
tempFragment = blankFragment;
}
if(menuItem.getItemId() == R.id.settings){
if (tempFragment ==null){
getFragment(settingsFragment);
}
else {
removeFragment(tempFragment);
getFragment(settingsFragment);
}
tempFragment = settingsFragment;
}
return true;
}
});
binding.navigationBottom.setOnItemReselectedListener(new NavigationBarView.OnItemReselectedListener() {
@Override
public void onNavigationItemReselected(@NonNull MenuItem item) {
}
});
}
public void getFragment(Fragment fragment){
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
transaction.setCustomAnimations(R.anim.slide_up, 0);
transaction.add(R.id.nav_host_fragment, fragment).addToBackStack(null).commit();
}
public void removeFragment(Fragment fragment){
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
transaction.remove(fragment).addToBackStack(null).commit();
}
【问题讨论】：
标签： java android google-maps-android-api-2 bottomnavigationview android-architecture-navigation