我正在使用带有 FragmentPagerAdapter 的 ViewPager。每个页面都是同一个 Fragment 类的实例，我总是使用固定数量的 7 页(从今天开始的一周中的几天)。调试显示所有 fragment 都在创建，并且在创建时具有正确的数据。一件有趣的事情是，虽然适配器按 0、1、2...6 的顺序创建 fragment ，但 fragment 的 onCreateView 是按 6、0、1、2...5 的顺序调用的。
当运行应用程序并打开此 Activity 时，第一个 fragment 页面是空白的，然后我可以滑动选项卡并看到除最后一个页面外的所有页面都是空白的。但是，最后一页显示的不是最后一天的数据，而是提前一天显示的倒数第二组数据。
我复制了另一个可用的 ViewPager/FragmentPagerAdapter，尽管它只有 3 个页面并且每个页面使用不同的 Fragment。
我没有看到我做错了什么，我一直在搜索一整天，但还没有找到答案。这里有很多类似的问题是通过使用 FragmentStatePagerAdapter 而不是 FragmentPagerAdapter 来解决的。我已经尝试过了，它的行为与当前完全相同。
这是托管 ViewPager 的 Activity :
public class ForecastFaveRowClickedActivity extends AppCompatActivity {
String distName = "";
public List<ForecastEntry> forecastEntries = new ArrayList<>();
ForecastPagerAdapter adapterViewPager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_forecast_detail);
// get the districts from the main activity
Bundle bundle = getIntent().getExtras();
distName = bundle.getString("districtName");
if (bundle.containsKey("forecastData")) {
forecastEntries = bundle.getParcelableArrayList("forecastData");
}
Collections.sort(forecastEntries);
// set up viewpager and display the first tab
// ViewPager for tabs
ViewPager viewPager = (ViewPager) findViewById(R.id.forecast_pager);
adapterViewPager = new ForecastPagerAdapter(getSupportFragmentManager(), ForecastFaveRowClickedActivity.this);
viewPager.setOffscreenPageLimit(7);
// set the tab titles based on the forecast list for this district
String[] days = new String[7];
int count = 0;
for (ForecastEntry forecastEntry : forecastEntries) {
days[count] = forecastEntry.forecastDay.substring(0,3);
count++;
}
adapterViewPager.setTabTitles(days);
viewPager.setAdapter(adapterViewPager);
//viewPager.setCurrentItem(0); // set to today's tab to start with
// give the tab layout to the viewpager
TabLayout tabLayout = (TabLayout) findViewById(R.id.forecast_sliding_date_tabs);
tabLayout.setupWithViewPager(viewPager);
}
// class for view pager adapter
public class ForecastPagerAdapter extends FragmentPagerAdapter {
private int NUM_ITEMS = 7;
private String tabTitles[] = new String[7];
private Context context;
public ForecastPagerAdapter(FragmentManager fm) {
super(fm);
}
public ForecastPagerAdapter(FragmentManager fragmentManager, Context context) {
super(fragmentManager);
this.context = context;
}
// returns total # of pages
@Override
public int getCount() {
return NUM_ITEMS;
}
// returns the fragment to display for that page
@Override
public Fragment getItem(int position) {
Fragment frag = new Fragment();
ForecastEntry forecastEntry;
Log.v("Fragment.getItem", Integer.toString(position));
forecastEntry = ((ForecastFaveRowClickedActivity)context).forecastEntries.get(position);
frag = FragmentForecastDay.newInstance(position, forecastEntry);
return frag;
}
// returns the page title for the top indicator
@Override
public CharSequence getPageTitle(int position) {
return tabTitles[position];
}
public void setTabTitles(String[] days) {
tabTitles = Arrays.copyOf(days, days.length);
}
}
}
这是该 Activity 的布局:
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout 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"
android:fitsSystemWindows="true"
tools:context="com.districtoverview.ForecastFaveRowClickedActivity">
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="@style/AppTheme.AppBarOverlay">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
android:titleTextColor="@color/colorWhite"
android:elevation="4dp"
android:theme="@style/AppTheme.AppBarOverlay"
app:popupTheme="@style/AppTheme.PopupOverlay" />
</android.support.design.widget.AppBarLayout>
<LinearLayout
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"
android:paddingBottom="6dp"
android:paddingTop="6dp"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:context="com.districtoverview.ForecastFaveRowClickedActivity"
tools:showIn="@layout/activity_forecast_detail"
android:orientation="vertical">
<android.support.design.widget.TabLayout
android:id="@+id/forecast_sliding_date_tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="top"
android:paddingBottom="2dp"
android:paddingTop="2dp"
app:tabMode="scrollable"
app:tabGravity="fill"
style="@style/customForecastTabLayout" />
<android.support.v4.view.ViewPager
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/forecast_pager"
android:layout_width="match_parent"
android:layout_height="0px"
android:layout_weight="1"
android:background="@android:color/white"
tools:context="com.districtoverview.ForecastFaveRowClickedActivity">
</android.support.v4.view.ViewPager>
</LinearLayout>
</android.support.design.widget.CoordinatorLayout>
这是 Fragment 类的代码。
public class FragmentForecastDay extends Fragment {
String label;
int page;
ForecastEntry forecastEntry;
public static FragmentForecastDay newInstance(int page, ForecastEntry forecastEntry) {
FragmentForecastDay fragment = new FragmentForecastDay();
Bundle args = new Bundle();
args.putParcelable("forecastEntry", forecastEntry);
args.putInt("page", page);
fragment.setArguments(args);
return fragment;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_forecast_day, container, false);
page = getArguments().getInt("page", 0);
forecastEntry = getArguments().getParcelable("forecastEntry");
return view;
}
@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
TextView headerDistNameTV = (TextView) getActivity().findViewById(R.id.dist_name_header_text);
headerDistNameTV.setText(parentActivity.distName);
TextView headerForecastDateTV = (TextView) getActivity().findViewById(R.id.forecast_date_header_text);
headerForecastDateTV.setText(forecastEntry.forecastDate);
TextView headerTotalTechsTV = (TextView) getActivity().findViewById(R.id.total_techs_header_text); headerTotalTechsTV.setText(Double.toString(forecastEntry.totalTechs));
TextView headerDayShiftTV = (TextView) getActivity().findViewById(R.id.day_shift_header_text);
headerDayShiftTV.setText("Day Shift");
TextView dayExpectedTechsTV = (TextView) getActivity().findViewById(R.id.day_shift_expected_text);
String dayExpectedTechs = "Expected " + Double.toString(forecastEntry.expectedTechs);
dayExpectedTechsTV.setText(dayExpectedTechs);
TextView headerAfterHoursTV = (TextView) getActivity().findViewById(R.id.after_hours_header_text);
headerAfterHoursTV.setText("After Hours");
TextView afterHoursExpectedTechsTV = (TextView) getActivity().findViewById(R.id.day_shift_expected_text);
String afterHoursExpectedTechs = "Expected " + Double.toString(forecastEntry.afterHoursExpected);
afterHoursExpectedTechsTV.setText(afterHoursExpectedTechs);
}
}
这是 fragment 布局:
<?xml version="1.0" encoding="utf-8"?>
<TableLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/forecast_day_table_layout"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="0.90"
android:paddingTop="4dp"
android:paddingBottom="4dp"
android:paddingLeft="4dp"
android:paddingRight="4dp"
android:weightSum="1">
<TableRow
android:id="@+id/row_dist_name_header"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="0.50">
<TextView
android:id="@+id/dist_name_header_text"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textColor="#000"
android:textAppearance="?android:attr/textAppearanceLarge"
android:paddingBottom="5dp" />
</TableRow>
<TableRow
android:id="@+id/row_date_header"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="0.50">
<TextView
android:id="@+id/forecast_date_header_text"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textColor="#000"
android:textAppearance="?android:attr/textAppearanceLarge"
android:paddingBottom="5dp" />
</TableRow>
<TableRow
android:id="@+id/row_total_techs_header"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="0.50">
<TextView
android:id="@+id/total_techs_header_text"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textColor="#000"
android:textAppearance="?android:attr/textAppearanceLarge"
android:paddingBottom="5dp" />
</TableRow>
<TableRow
android:id="@+id/row_total_techs"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="0.50">
<TextView
android:id="@+id/total_techs_text"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textColor="#000"
android:textAppearance="?android:attr/textAppearanceLarge"
android:paddingBottom="5dp" />
</TableRow>
<TableRow
android:id="@+id/row_day_shift_header"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="0.50">
<TextView
android:id="@+id/day_shift_header_text"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textColor="#000"
android:textAppearance="?android:attr/textAppearanceLarge"
android:paddingBottom="5dp" />
</TableRow>
<TableRow
android:id="@+id/row_day_shift_expected"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="0.50">
<TextView
android:id="@+id/day_shift_expected_text"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textColor="#000"
android:textAppearance="?android:attr/textAppearanceLarge"
android:paddingBottom="5dp" />
</TableRow>
<TableRow
android:id="@+id/row_after_hours_header"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="0.50">
<TextView
android:id="@+id/after_hours_header_text"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textColor="#000"
android:textAppearance="?android:attr/textAppearanceLarge"
android:paddingBottom="5dp" />
</TableRow>
<TableRow
android:id="@+id/row_after_hours_expected"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="0.50">
<TextView
android:id="@+id/after_hours_expected_text"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textColor="#000"
android:textAppearance="?android:attr/textAppearanceLarge"
android:paddingBottom="5dp" />
</TableRow>
</TableLayout>
最佳答案
这是由于我错误地使用了 getActivity() 而不是 View 造成的。我从位于主要 Activity 上的另一组滑动选项卡复制了代码，但这组代码位于一个 fragment 中。我需要引用父 fragment 的 View 。
例如:
(TextView) getActivity().findViewById(R.id.dist_name_header_text);
应该是这样的:
(TextView) view.findViewById(R.id.dist_name_header_text);
一旦我进行了此更改， View 寻呼机中使用的所有子 fragment 都将正确显示。
关于带有 FragmentPageAdapter 的 Android ViewPager - 只有最后一个 fragment 页面可见，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/37220906/