我正在创建一个带有动态片段创建的片段结构。片段中的每个项目都会创建下一个片段。在场景中，我将所有这些片段存储在片段的ArrayList中，以便我可以轻松替换创建的片段。
现在我通过从特定索引中删除片段并添加新片段来替换ArrayList中的片段。但是当我尝试从该特定索引获取片段时，它会返回旧数据而不再调用FragmentStateAdapter的getItem函数。
这是我的主要课程。
public class MainActivity extends FragmentActivity implements
onPageSelectedListener {
SectionsPagerAdapter mSectionsPagerAdapter;
static int current, listItem;
static String TAG = "MainActivity";
static ViewPager mViewPager;
static ArrayList<Fragment> FragmentList;
static ArrayList<String> titles;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
init();
}
public void init(){
FragmentList = new ArrayList<Fragment>();
titles = new ArrayList<String>();
mViewPager = (ViewPager) findViewById(R.id.pager);
mSectionsPagerAdapter = new SectionsPagerAdapter(
getSupportFragmentManager());
mViewPager.setAdapter(mSectionsPagerAdapter);
}
public void addPage(int position, String title, String file, String tag) {
Fragment fragment = new DummySectionFragment();
Bundle args = new Bundle();
args.putString(DummySectionFragment.ARG_FILE_NAME, file);
args.putString(DummySectionFragment.ARG_FILE_TAG, tag);
args.putInt(DummySectionFragment.ARG_SECTION_NUMBER, position);
fragment.setArguments(args);
titles.add(position, title);
FragmentList.add(position, fragment);
}
public void NextScreen(int position, String title, String file, String tagname) {
if(FragmentList.size()>(position-1)){
for(int i=position; i<FragmentList.size(); i++){
FragmentList.remove(i);
}
}
addPage(position, title, file, tagname);
mViewPager.setCurrentItem(position);
}
public static class PageChanger extends
ViewPager.SimpleOnPageChangeListener {
private int currentPage;
@Override
public void onPageSelected(int position) {
currentPage = position;
}
public int getCurrentScreen() {
return currentPage;
}
}
public class SectionsPagerAdapter extends FragmentStatePagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
addPage(0, "Main Fragment", "test.xml", "mytag");
}
@Override
public Fragment getItem(int position) {
return FragmentList.get(position);
}
@Override
public int getCount() {
return FragmentList.size();
}
@Override
public CharSequence getPageTitle(int position) {
if (position == 0) {
return "Main Categories";
}
getItem(position);
return titles.get(position);
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
super.destroyItem(container, position, object);
}
}
public static class DummySectionFragment extends Fragment {
public static final String ARG_SECTION_NUMBER = "section_number";
public static final String ARG_FILE_NAME = "file_name";
public static final String ARG_FILE_TAG = "tag_name";
public DummySectionFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
savedInstanceState = this.getArguments();
ListView parent_list = new ListView(getActivity());
String file_name = savedInstanceState.getString(ARG_FILE_NAME);
String tag_name = savedInstanceState.getString(ARG_FILE_TAG);
int current_level = savedInstanceState.getInt(ARG_SECTION_NUMBER);
PullParser pull = new PullParser(getActivity());
pull.pullXml(file_name, tag_name);
parent_list.setAdapter(new ListAdapter(getActivity(),
PullParser.Xml_Tag_Info, current_level));
return parent_list;
}
}
@Override
public void onPageSelected(int pageno) {
current = pageno;
}
}
答案 0 :(得分：1)
我找到答案只是为了在进行必要的更改后重新实例化适配器。编辑后的代码在这里。
public class MainActivity extends FragmentActivity {
SectionsPagerAdapter mSectionsPagerAdapter;
static int current, listItem;
static String TAG = "MainActivity";
static boolean flag = false;
/**
* The {@link ViewPager} that will host the section contents.
*/
static ViewPager mViewPager;
static ArrayList<DummySectionFragment> FragmentList;
static ArrayList<String> titles;
static FragmentManager fragManager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
init();
}
public void init() {
FragmentList = new ArrayList<DummySectionFragment>();
titles = new ArrayList<String>();
mViewPager = (ViewPager) findViewById(R.id.pager);
fragManager = getSupportFragmentManager();
mSectionsPagerAdapter = new SectionsPagerAdapter(fragManager);
mViewPager.setAdapter(mSectionsPagerAdapter);
titles.add(0, "Main Categories");
}
public void addPage(final int position, String file, String tag) {
DummySectionFragment fragment = new DummySectionFragment();
Bundle args = new Bundle();
args.putString(DummySectionFragment.ARG_FILE_NAME, file);
args.putString(DummySectionFragment.ARG_FILE_TAG, tag);
args.putInt(DummySectionFragment.ARG_SECTION_NUMBER, position);
fragment.setArguments(args);
try {
FragmentList.set(position, fragment);
} catch (IndexOutOfBoundsException e) {
FragmentList.add(position, fragment);
} catch (Exception e) {
e.printStackTrace();
}
}
public void destroyFragment(int position) {
SectionsPagerAdapter pagerAdapter = (SectionsPagerAdapter) mViewPager
.getAdapter();
pagerAdapter.destroyItem(mViewPager, position,
FragmentList.get(position));
pagerAdapter.notifyDataSetChanged();
}
public void addFragment(int position, Object object) {
SectionsPagerAdapter pagerAdapter = (SectionsPagerAdapter) mViewPager
.getAdapter();
pagerAdapter.notifyDataSetChanged();
}
public void NextScreen(int position, String title, String file,
String tagname) {
if (FragmentList.size() > position - 1) {
for (int i = FragmentList.size() - 1; i > position; i--) {
titles.remove(i);
FragmentList.remove(i);
}
titles.trimToSize();
FragmentList.trimToSize();
}
titles.add(position, title);
addPage(position, file, tagname);
mViewPager.setAdapter(new SectionsPagerAdapter(fragManager));
mViewPager.setCurrentItem(position);
}
/**
* A {@link FragmentPagerAdapter} that returns a fragment corresponding to
* one of the sections/tabs/pages.
*/
public class SectionsPagerAdapter extends FragmentStatePagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
addPage(0, "catlist.xml", "pid-0");
}
@Override
public Fragment getItem(int position) {
return FragmentList.get(position);
}
public void setId() {
}
@Override
public int getCount() {
return FragmentList.size();
}
@Override
public int getItemPosition(Object object) {
return FragmentList.indexOf(object);
}
@Override
public CharSequence getPageTitle(int position) {
Log.v("titlePosition", position + "");
return titles.get(position);
}
}
/**
* A dummy fragment representing a section of the app, but that simply
* displays dummy text.
*/
public static class DummySectionFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
public static ArrayList<Xml_Item_Data> resultList = new ArrayList<Xml_Item_Data>();
public static final String ARG_SECTION_NUMBER = "section_number";
public static final String ARG_FILE_NAME = "file_name";
public static final String ARG_FILE_TAG = "tag_name";
ListView parent_list;
public static Bundle setValues;
public DummySectionFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
savedInstanceState = this.getArguments();
parent_list = new ListView(getActivity());
String file_name = savedInstanceState.getString(ARG_FILE_NAME);
String tag_name = savedInstanceState.getString(ARG_FILE_TAG);
int current_level = savedInstanceState.getInt(ARG_SECTION_NUMBER);
PullParser pull = new PullParser(getActivity());
pull.pullXml(file_name, tag_name);
ListAdapter list_Creator = new ListAdapter(getActivity(),
PullParser.Xml_Tag_Info, current_level);
parent_list.setAdapter(list_Creator);
return parent_list;
}
}
}
答案 1 :(得分：0)
我认为您可以尝试在getItemPosition（）方法中返回POSITION_NONE。就像这里：How to force ViewPager to re-instantiate its items