我找不到在Android.App中找到FragmentPagerAdapter。
我不想使用Android.Support.V4.App中的Fragment，因为我的目标API是 14及更高版本（Android 4.0及更高版本）。所以，我想使用Android.App.Fragments的平原， 以及相关的课程。
我只在Android.Support.V4.App中找到它，但这还不够 对我来说b / c我正在尝试使用Android.App.Fragment（不是Android.Support.V4.App.Fragment的） 还有Android.App（而不是Android.Support.V4.App）中的相关类，而我的代码不会 编译，如果我从FragmentPagerAdapter派生我的寻呼机，如果它来自支持库， 因为Android.App和Android.Support.V4.App之间的类型不匹配。
就像这里的案例Cannot be cast to android.app.Fragment一样，我应该使用的是“普通”寻呼机（PagerAdapter）类 FragmentPagerAdapter的位置或其他东西（就像你从普通的Activity派生出来的那样） 当针对API 11或更高版本时，不是FragmentActivity。
以下是我正在使用的示例代码（它来自https://github.com/xamarin/monodroid-samples/tree/master/Support4中的MonoDroid示例的Support4.sln解决方案中的FragmentPagerSupport.cs文件。）
我已经注释掉引用Android.Support.V4.App的行并将其替换为 引用Android.App的代码。我找不到Android.Support.V4.App之外没有FramePagerAdapter，我真的需要它。）
感谢。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;
//using Android.Support.V4.App;
//using Android.Support.V4.View;
namespace Support4
{
[Activity (Label = "@string/fragment_pager_support")]
[IntentFilter (new[]{Intent.ActionMain}, Categories = new[]{ "mono.support4demo.sample" })]
//public class FragmentPagerSupport : FragmentActivity
public class FragmentPagerSupport : Activity
{
const int NUM_ITEMS = 10;
MyAdapter adapter;
ViewPager pager;
protected override void OnCreate (Bundle bundle)
{
base.OnCreate (bundle);
SetContentView(Resource.Layout.fragment_pager);
//adapter = new MyAdapter(SupportFragmentManager);
adapter = new MyAdapter(FragmentManager);
pager = FindViewById<ViewPager>(Resource.Id.pager);
pager.Adapter = adapter;
var button = FindViewById<Button>(Resource.Id.goto_first);
button.Click += (sender, e) => {
pager.CurrentItem = 0;
};
button = FindViewById<Button>(Resource.Id.goto_last);
button.Click += (sender, e) => {
pager.CurrentItem = NUM_ITEMS - 1;
};
}
// ?????????????????????????????????????????????????
// - where is FragmentPagerAdapter
// ?????????????????????????????????????????????????
protected class MyAdapter : FragmentPagerAdapter
{
public MyAdapter(FragmentManager fm) : base(fm)
{
}
public override int Count {
get {
return NUM_ITEMS;
}
}
public override Fragment GetItem (int position)
{
return new ArrayListFragment(position);
}
}
protected class ArrayListFragment : ListFragment
{
int num;
public ArrayListFragment()
{
}
public ArrayListFragment(int num)
{
var args = new Bundle();
args.PutInt("num", num);
Arguments = args;
}
public override void OnCreate (Bundle p0)
{
base.OnCreate (p0);
num = Arguments != null ? Arguments.GetInt("num") : 1;
}
public override View OnCreateView (LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
var v = inflater.Inflate(Resource.Layout.fragment_pager_list, container, false);
var tv = v.FindViewById<TextView>(Resource.Id.text);
tv.Text = "Fragment #" + num;
return v;
}
public override void OnActivityCreated (Bundle p0)
{
base.OnActivityCreated (p0);
ListAdapter = new ArrayAdapter<string>(Activity, Android.Resource.Layout.SimpleListItem1, Cheeses.cheeseStrings);
}
public override void OnListItemClick(ListView l, View v, int position, long id) {
Console.WriteLine ( "Item clicked: " + id);
}
}
}
}
答案 0 :(得分：201)
android.support.v13.app.FragmentPagerAdapter中有一个应该做你想做的事。它是用于非支持片段的FragmentPagerAdapter。
Android Studio安装
请添加以下Gradle依赖项
dependencies {
compile 'com.android.support:support-v13:+'
}
答案 1 :(得分：17)
呃，你只需要使用V13支持库中的FragmentPagerAdapter
Android.Support.V13.App.FragmentPagerAdapter
然后可以从“普通”库/命名空间中使用所有其他与Fragment相关的类，但ViewPager除外，但这没什么大不了的。
以下是完整性示例（来自https://github.com/xamarin/monodroid-samples/的修改后的“Support4”示例）：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Util;
using Android.Views;
using Android.Widget;
using Java.Lang;
using Android.Support.V4.View;
using Fragment = Android.App.Fragment;
namespace Support4
{
[Activity (Label = "@string/fragment_pager_support")]
[IntentFilter (new[]{Intent.ActionMain}, Categories = new[]{ "mono.support4demo.sample" })]
public class FragmentPagerSupport : Activity
//public class FragmentPagerSupport : FragmentActivity
{
const int NUM_ITEMS = 4;
protected MyAdapter _pagerAdapter;
protected ViewPager _viewPager;
protected override void OnCreate (Bundle bundle)
{
base.OnCreate (bundle);
SetContentView(Resource.Layout.fragment_pager);
List<Fragment> fragments = new List<Fragment>();
// *** MonoDroid 4.2.7 letter case bug *** make's first letter lower.
//string typeName = typeof(Fragment1).FullName;
string typeName = "support4." + typeof(Fragment1).Name;
fragments.Add(Fragment.Instantiate(this, typeName));
fragments.Add(Fragment.Instantiate(this, typeName));
fragments.Add(Fragment.Instantiate(this, typeName));
fragments.Add(Fragment.Instantiate(this, typeName));
//adapter = new MyAdapter(SupportFragmentManager);
_pagerAdapter = new MyAdapter(FragmentManager, fragments);
_viewPager = FindViewById<ViewPager>(Resource.Id.view_pager);
_viewPager.Adapter = _pagerAdapter;
}
public override bool OnTouchEvent(MotionEvent e)
{
return base.OnTouchEvent(e);
}
protected class MyAdapter : Android.Support.V13.App.FragmentPagerAdapter
{
private List<Fragment> _fragments;
public override Java.Lang.Object InstantiateItem(View p0, int p1)
{
return base.InstantiateItem(p0, p1);
}
public MyAdapter(Android.App.FragmentManager fm)
: base(fm)
{
}
//public MyAdapter(Android.Support.V4.App.FragmentManager fm, List<Android.Support.V4.App.Fragment> fragments)
// : base(fm)
public MyAdapter(FragmentManager fm, List<Fragment> fragments)
: base(fm)
{
_fragments = fragments;
}
public override int Count {
get {
return NUM_ITEMS;
}
}
//public override Android.Support.V4.App.Fragment GetItem(int p0)
public override Fragment GetItem(int p0)
{
return _fragments[p0];
}
public override float GetPageWidth(int p0)
{
//return base.GetPageWidth(p0);
//base.GetPageWidth(p0);
return (float)(0.5f);
}
}
}
//public class Fragment1 : Android.Support.V4.App.Fragment
public class Fragment1 : Fragment
{
int num;
private static int _colorIndex = 0;
private static Android.Graphics.Color[] _colors = new[] { Android.Graphics.Color.Aqua, Android.Graphics.Color.DarkViolet,
Android.Graphics.Color.Coral, Android.Graphics.Color.Bisque};
public Fragment1()
{
}
public Fragment1(int num)
{
var args = new Bundle();
args.PutInt("num", num);
Arguments = args;
}
public override void OnCreate(Bundle p0)
{
base.OnCreate(p0);
num = Arguments != null ? Arguments.GetInt("num") : 1;
}
public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
View v = inflater.Inflate(Resource.Layout.aaaaa, container, false);
TextView tv = v.FindViewById<TextView>(Resource.Id.text);
tv.Text = "# " + _colorIndex;
tv.SetBackgroundColor(_colors[_colorIndex++]);
return v;
}
public override void OnActivityCreated(Bundle p0)
{
base.OnActivityCreated(p0);
}
}
}
<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright (C) 2010 The Android Open Source Project
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
-->
<!-- Top-level content view for the simple fragment sample. -->
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal" android:padding="4dip"
android:layout_width="match_parent" android:layout_height="match_parent">
<!--android:gravity="center_horizontal"-->
<android.support.v4.view.ViewPager
android:id="@+id/view_pager"
android:layout_width="700dip"
android:layout_height="match_parent"
android:layout_weight="1"
android:background="#FFCCFFFF">
<!--android:layout_width="match_parent"-->
</android.support.v4.view.ViewPager>
</LinearLayout>
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/screen_container"
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView android:id="@+id/text"
android:layout_width="match_parent" android:layout_height="match_parent"
android:gravity="center_vertical|center_horizontal"
android:textAppearance="?android:attr/textAppearanceMedium"
android:text="@string/hello_world"
android:background="#FF335555"/>
</LinearLayout>
答案 2 :(得分：2)
将此依赖项添加到gradle依赖项：
compile 'com.android.support:support-v13:+'
并像这样使用android.support.v13.app.FragmentPagerAdapter（我只是修改了android studio中的官方演示项目：文件→新建→新项目→下一个→下一个→标签活动→下一个→完成）：
import android.app.Fragment;
import android.app.FragmentManager;
import android.support.v13.app.FragmentPagerAdapter;
import com.google.android.gms.maps.MapFragment;
/** A simple FragmentPagerAdapter that returns a MapFragment and a PreferenceFragment. */
public class MainActivityAdapter extends FragmentPagerAdapter {
private MapFragment mapFragment;
private PreferencesFragment preferencesFragment;
public MainActivityAdapter(FragmentManager fm) {
super(fm);
mapFragment = MapFragment.newInstance();
preferencesFragment = new PreferencesFragment();
}
@Override
public int getCount() {
return 2;
}
@Override
public Fragment getItem(int position) {
switch (position) {
case 0:
return mapFragment;
case 1:
return preferencesFragment;
default:
return null;
}
}
}
答案 3 :(得分：0)
有同样的问题。我的解决方案是从android.support.v4.app.FragmentPagerAdapter复制代码，然后将导入的Fragment类更改为android.app.Fragment。然后进行其他较小的改动以消除所有错误。令我惊讶的是，它运作完美。 与添加您不需要的支持库相比，IMO更为简单。
import android.app.Fragment;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.os.Parcelable;
import android.support.v4.view.PagerAdapter;
import android.view.View;
import android.view.ViewGroup;
/**
* PagerAdapter for ViewPager that is compatible with android.app.Fragment.
*/
abstract class FragmentPagerAdapter extends PagerAdapter {
private final FragmentManager mFragmentManager;
private FragmentTransaction mCurTransaction = null;
private Fragment mCurrentPrimaryItem = null;
/**
* Returns a unique id for the fragment on the given position.
* For example this can be the view id that is used on the page's fragment.
* @param position The page index
* @return An id that is unique with respect to the pages in the adapter.
*/
abstract long getItemId(int position);
/**
* Returns the fragment for the given page index.
* @param position The page index
* @return The fragment
*/
abstract Fragment getItem(int position);
public FragmentPagerAdapter(FragmentManager fragmentManager) {
super();
mFragmentManager = fragmentManager;
}
@Override
public Object instantiateItem(ViewGroup container, int position) {
if (mCurTransaction == null) {
mCurTransaction = mFragmentManager.beginTransaction();
}
final long itemId = getItemId(position);
// Do we already have this fragment?
String name = makeFragmentName(container.getId(), itemId);
Fragment fragment = mFragmentManager.findFragmentByTag(name);
if (fragment != null) {
mCurTransaction.attach(fragment);
} else {
fragment = getItem(position);
mCurTransaction.add(container.getId(), fragment,
makeFragmentName(container.getId(), itemId));
}
if (fragment != mCurrentPrimaryItem) {
fragment.setMenuVisibility(false);
}
return fragment;
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
if (mCurTransaction == null) {
mCurTransaction = mFragmentManager.beginTransaction();
}
mCurTransaction.detach((Fragment) object);
}
@SuppressWarnings("ReferenceEquality")
@Override
public void setPrimaryItem(ViewGroup container, int position, Object object) {
Fragment fragment = (Fragment)object;
if (fragment != mCurrentPrimaryItem) {
if (mCurrentPrimaryItem != null) {
mCurrentPrimaryItem.setMenuVisibility(false);
}
if (fragment != null) {
fragment.setMenuVisibility(true);
}
mCurrentPrimaryItem = fragment;
}
}
@Override
public void finishUpdate(ViewGroup container) {
if (mCurTransaction != null) {
mCurTransaction.commitAllowingStateLoss();
mCurTransaction = null;
}
}
@Override
public boolean isViewFromObject(View view, Object object) {
return ((Fragment)object).getView() == view;
}
@Override
public Parcelable saveState() {
return null;
}
@Override
public void restoreState(Parcelable state, ClassLoader loader) {
}
private static String makeFragmentName(int viewId, long id) {
return "android:switcher:" + viewId + ":" + id;
}
}
答案 4 :(得分：0)
截至2019年，使用AndroidX
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