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我想實現一個NavigationDrawer與在主活動的幀結構片段。導航抽屜應該在我的「主」片段，GMAP片段和其他片段之間切換。作爲「主要」片段，此活動首次啓動時也會添加此片段（如代碼中所示）。問題是當我替換物品上的碎片時，碎片被破壞，地圖碎片重新被創建。我更希望的片段創建一次，並以某種方式保存其狀態時，我與其他碎片將其裝回佔位片段的交換和生命週期
的頂部，這是地圖片段：
public class Mapfragment extends Fragment
{
MapView mMapView;
private GoogleMap googleMap;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// inflate and return the layout
View v = inflater.inflate(R.layout.activity_map_fragment, container,
false);
mMapView = (MapView) v.findViewById(R.id.mapView);
mMapView.onCreate(savedInstanceState);
mMapView.onResume();// needed to get the map to display immediately
try {
MapsInitializer.initialize(getActivity().getApplicationContext());
} catch (Exception e) {
e.printStackTrace();
}
Camera camera = UserDetails.getInstance().getCameras().get(0);
googleMap = mMapView.getMap();
// latitude and longitude
double latitude = camera.getLatitude();
double longitude = camera.getLongitude();
// create marker
MarkerOptions marker = new MarkerOptions().position(
new LatLng(latitude, longitude)).title("Hello Maps");
// Changing marker icon
marker.icon(BitmapDescriptorFactory
.defaultMarker(BitmapDescriptorFactory.HUE_ROSE));
// adding marker
googleMap.addMarker(marker);
CameraPosition cameraPosition = new CameraPosition.Builder()
.target(new LatLng(camera.getLatitude(), camera.getLongitude())).zoom(18).build();
googleMap.animateCamera(CameraUpdateFactory
.newCameraPosition(cameraPosition));
// Perform any camera updates here
return v;
}@Override
public void onResume() {
super.onResume();
Log.d("Map fragment Resumed", "sdfsdf");
mMapView.onResume();
}
@Override
public void onPause() {
super.onPause();
Log.d("Map fragment paused","dsffs");
mMapView.onPause();
}
@Override
public void onDestroy() {
super.onDestroy();
Log.d("Map fragment Destroyed", "sdfsdf");
mMapView.onDestroy();
}
@Override
public void onLowMemory() {
super.onLowMemory();
mMapView.onLowMemory();
}
}
和主要活動
公共類Main_screen擴展AppCompatActivity 實現導航View.OnNavigationItemSelectedListener {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main_screen);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
Fragment fragment = new Mapfragment();
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.setDrawerListener(toggle);
toggle.syncState();
NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
View hView = navigationView.getHeaderView(0);
TextView username_header = (TextView)hView.findViewById(R.id.username_header);
username_header.setText(UserDetails.getInstance().getUsername());
ImageView img= (ImageView)hView.findViewById(R.id.imageView);
img.setImageBitmap(UserDetails.getInstance().getImage());
//adding main fragment upon Main screen activity Oncreate
android.support.v4.app.FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction().add(R.id.frame_layout_placeholder,fragment).commit();
}
@Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main_screen, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
// Handle navigation view item clicks here.
android.support.v4.app.Fragment fragment = null;
android.support.v4.app.FragmentTransaction fragmentManager = getSupportFragmentManager().beginTransaction();
int id = item.getItemId();
if (id == R.id.map_frag_item) {
fragment = new Mapfragment();
} else if (id == R.id.nav_gallery) {
fragment = new FragmentTwo();
} else if (id == R.id.nav_slideshow) {
} else if (id == R.id.nav_manage) {
} else if (id == R.id.nav_share) {
} else if (id == R.id.nav_send) {
}
fragmentManager.replace(R.id.frame_layout_placeholder, fragment).commit();
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
return true;
}
正在上的活動的OnCreate加入主GMAP片段和衣服被在OnItemSelected（）取代。 非常感謝！
Malith嗨，這裏定義myFragmentMap？它是什麼類型？ – Tomb