在menu / Genre.xml中：
<?xml version="1.0" encoding="UTF-8" ?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
<group android:checkableBehavior="single">
<item
android:id="@+id/nav_home"
android:icon="@drawable/ic_home_black_48dp"
android:title="Home" />
<item
android:id="@+id/nav_genre"
android:icon="@drawable/ic_toc_black_48dp"
android:title="Genres" />
<item
android:id="@+id/nav_download"
android:icon="@drawable/ic_get_app_black_48dp"
android:title="Download" />
</group>
<item android:title="Account">
<menu>
<group android:checkableBehavior="single">
<item
android:id="@+id/nav_about"
android:icon="@drawable/ic_lock_open_black_48dp"
android:title="About"/>
<item
android:id="@+id/nav_signout"
android:icon="@drawable/ic_perm_identity_black_48dp"
android:title="Sign out"/>
</group>
</menu>
</item>
</menu>在layout / GenreFragment.axml中
<?xml version="1.0" encoding="utf-8"?>
<ListView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/lst_genre"
android:layout_height="match_parent"
android:layout_width="match_parent" />在viewModel / GenreFragmentVM中：
public class GenerFragmentVM : Fragment
{
public override void OnCreate (Bundle savedInstanceState)
{
base.OnCreate (savedInstanceState);
// Create your fragment here
}
ListView lst;
public override View OnCreateView (LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
// Use this to return your custom view for this Fragment
// return inflater.Inflate(Resource.Layout.YourFragment, container, false);
base.OnCreateView (inflater, container, savedInstanceState);
var view = inflater.Inflate (Resource.Layout.abc_list_menu_item_layout, container, false);
lst = view.FindViewById<ListView> (Resource.Id.lst_genre);
lst.SetAdapter(new ArrayAdapter<string> (this,Resource.Layout.abc_list_menu_item_layout,Resource.Menu.Genres));
//Event click on listview
lst.ItemClick+= delegate(object sender, AdapterView.ItemClickEventArgs e) {
};
}
}Error: (19,19): Error CS1502: The best overloaded method match for
`Android.Widget.ArrayAdapter.ArrayAdapter(Android.Content.Context,
int, int)’ has some invalid arguments (CS1502) (SoundCloud)(45,45): Error CS1503: Argument
#1' cannot convertSoundCloud.GenerFragment’ expression to type
`Android.Content.Context’ (CS1503) (SoundCloud)
在Mainactivity.cs中
protected override void OnCreate (Bundle savedInstanceState)
{
base.OnCreate (savedInstanceState);
// Set our view from the "main" layout resource
//ActionBar.NavigationMode = ActionBarNavigationMode.Tabs;
SetContentView (Resource.Layout.Main);
var mToolbar= FindViewById<Toolbar> (Resource.Id.toolbar);
//Toolbar will now take on default action bar chacracteritics
SetActionBar(mToolbar);
ActionBar.Title = "home";
//Enable suppport action bar to display hamburger
//ActionBar.SetHomeAsUpIndicator(Resource.Drawable.icon_hambuger);
//ActionBar.SetDisplayHomeAsUpEnabled (true);
//Set menu hambuger
ActionBar.SetHomeAsUpIndicator (Resource.Drawable.ic_menu_white_24dp);
ActionBar.SetDisplayHomeAsUpEnabled (true);
drawerLayout = FindViewById<DrawerLayout> (Resource.Id.drawer_layout);
navigationView = FindViewById<NavigationView> (Resource.Id.nav_view);
//Event click on navigatonView
//
CreateFragments();
LoadInditialFragment ();
navigationView.NavigationItemSelected += NavigationView_NavigationItemSelected;
}
void NavigationView_NavigationItemSelected (object sender, NavigationView.NavigationItemSelectedEventArgs e)
{
e.MenuItem.SetChecked (true);
if (e.MenuItem.ItemId != currentFragmentId) {
SwitchFragment (e.MenuItem.ItemId);
}
drawerLayout.CloseDrawers ();
}
// Khoi tao gia tri cho fragment layout
private void CreateFragments()
{
explorFragment= new ExploreFragment();
genreFragment = new GenerFragment ();
}
//
private void LoadInditialFragment ()
{
var transaction = FragmentManager.BeginTransaction ();
transaction.Add (Resource.Id.fragmentContainer, explorFragment).Hide (explorFragment);
transaction.Add (Resource.Id.fragmentContainer, genreFragment);
transaction.Commit ();
}
private void SwitchFragment(int FragmentId)
{
var transaction = FragmentManager.BeginTransaction ();
switch (currentFragmentId) {
case Resource.Id.nav_home:
transaction.Hide (explorFragment).Commit ();
break;
case Resource.Id.nav_genre:
transaction.Hide (genreFragment).Commit ();
break;
}
transaction = FragmentManager.BeginTransaction ();
switch (FragmentId) {
case Resource.Id.nav_home:
transaction.Show (explorFragment);
transaction.Commit ();
break;
case Resource.Id.nav_genre:
transaction.Show (genreFragment);
transaction.Commit ();
break;
}
currentFragmentId = FragmentId;
}
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true">
<!-- your content layout -->
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:minHeight="?attr/actionBarSize"
android:background="?attr/colorPrimary"
android:titleTextColor="@android:color/background_light" />
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<FrameLayout
android:id="@+id/fragmentContainer"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>
</RelativeLayout>
<android.support.design.widget.NavigationView
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
android:id="@+id/nav_view"
app:headerLayout="@layout/drawer_header"
app:menu="@menu/navmenu" />
</android.support.v4.widget.DrawerLayout>最佳答案 您的第一个构建错误的原因如SushiHangover所解释,即您应该将父Activity的实例(承载此片段的活动)作为ArrayAdapter构造函数的第一个参数传递.
运行时的原因(对象引用未设置为对象的实例)异常是因为“Activity”属性为null.仅当父Activity的Fragment附件完成时,“Activity”属性才会有值.基本上,您不应该从OnCreateView方法访问Activity属性.您可以在OnAttach或OnCreate回调中初始化列表视图.我正在修改你的代码.
`public class GenerFragmentVM : Fragment
{
ListView lst;
public override void OnCreate (Bundle savedInstanceState)
{
base.OnCreate (savedInstanceState);
lst.SetAdapter(new ArrayAdapter<string> (this.Activity,Resource.Layout.abc_list_menu_item_layout,Resource.Menu.Genres));
}
public override View OnCreateView (LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
base.OnCreateView (inflater, container, savedInstanceState);
var view = inflater.Inflate (Resource.Layout.abc_list_menu_item_layout, container, false);
lst = view.FindViewById<ListView> (Resource.Id.lst_genre);
//Event click on listview
lst.ItemClick+= delegate(object sender, AdapterView.ItemClickEventArgs e) {
};
return view;
}
}
