Android，如何混合 ActionBar.Tab + View Pager + ListFragment [英] Android, How to mix ActionBar.Tab + View Pager + ListFragment
问题描述
我一直在尝试测试如何将所有这些东西混合在一起，但我遇到了问题！！我只想要一个使用 ActionBar.Tab 的带有三个选项卡的应用程序.例如，此选项卡可以是动作、冒险和动画电影类型，用户可以滑动选项卡，因此它将使用 ViewPager，每个选项卡将显示该类型的电影列表.不需要三个不同的片段类，因为所有选项卡都将采用相同的格式作为简单列表.我遇到了问题，因为当我选择第二个选项卡时，onPageSelected 的位置是 1，
I've been trying to test how to mix all these things together and I'm having problems!! I just want an app with three tabs using the ActionBar.Tab. For example, this tabs can be movies genres Action, Adventure and Animation, the user can swipe through the tabs, so it will use the ViewPager and each tab will show a list of movies of that genre. There's no need to have three different fragments classes because all tabs will be the same format a simple list. And I'm having problems because when I select the second tab, the position for onPageSelected is 1,
mViewPager = (ViewPager) findViewById(R.id.pager);
mViewPager.setAdapter(mCollectionPagerAdapter);
mViewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
@Override
public void onPageSelected(int position) {
mActionBar.setSelectedNavigationItem(position);
}
});
这会导致调用 CollectionPagerAdapter 类中的 public Fragment getItem(int i) 方法，但是 i 的值是 2 NOT 1，因此它调用 TabFragment 类的 createView 的值为 2 NOT 1，因此选项卡无法成功刷新.
This causes the call to the method public Fragment getItem(int i) inside the CollectionPagerAdapter class, but then the value of i is 2 NOT 1, so then it calls the createView for the TabFragment class with a value of 2 NOT 1, so tabs are not refreshing successfully.
任何帮助将不胜感激！
创建标签的代码，
// For each of the sections in the app, add a tab to the action bar.
for (int i = 0; i < mCollectionPagerAdapter.getCount(); i++) {
mActionBar.addTab(mActionBar.newTab()
.setText(mGenres.get(i).getName())
.setTabListener(this));
//Let's request the movies for the first three genres
new GetMoviesByGenre().execute(mGenres.get(i).getId());
}
选择标签时，
@Override
public void onTabSelected(ActionBar.Tab tab, android.app.FragmentTransaction arg1) {
//Let's update the dataset for the selected genre
TabFragment fragment =
(TabFragment) getSupportFragmentManager().findFragmentByTag(
"android:switcher:"+R.id.pager+":"+tab.getPosition());
if(fragment != null) // could be null if not instantiated yet
{
if(fragment.getView() != null)
{
fragment.updateDisplay(tab.getPosition()); // do what updates are required
}
}
mViewPager.setCurrentItem(tab.getPosition());
}
CollectionPageAdapter 类
CollectionPageAdapter class
public class CollectionPagerAdapter extends FragmentPagerAdapter {
final int NUM_ITEMS = 3; // number of tabs
List<Fragment> fragments = new ArrayList<Fragment>();
public Fragment getItem(int pos) {
return fragments.get(pos);
}
public void addFragment(Fragment f) {
fragments.add(f);
}
public CollectionPagerAdapter(FragmentManager fm) {
super(fm);
//Let's add the fragments
for (int i=0;i<NUM_ITEMS;i++)
{
Fragment fragment = new TabFragment();
Bundle args = new Bundle();
args.putInt(TabFragment.ARG_OBJECT, 0);
fragment.setArguments(args);
addFragment (fragment);
}
}
@Override
public int getCount() {
return NUM_ITEMS;
}
}
TabFragment 类
TabFragment class
public class TabFragment extends ListFragment {
public static final String ARG_OBJECT = "object";
private MoviesAdapter m_Adapter;
private ArrayList <Movie> mMovies = new ArrayList<Movie>();
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
// you only need to instantiate these the first time your fragment is
// created; then, the method above will do the rest
if (m_Adapter == null) {
m_Adapter = new MoviesAdapter(getActivity(), mMovies);
}
setListAdapter(m_Adapter);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
int position = getArguments().getInt(ARG_OBJECT); // to check is the right fragment
View rootView = inflater.inflate(R.layout.tabs, container, false);
return rootView;
}
public void updateDisplay (int type)
{
GlobalVars gv = (GlobalVars)getActivity().getApplicationContext();
switch (type)
{
case 0:
mMovies = gv.getActionMovies();
break;
case 1:
mMovies = gv.getAdventureMovies();
break;
case 2:
mMovies = gv.getAnimationMovies();
break;
}
m_Adapter.notifyDataSetChanged();
}
}
我不知道我做错了什么，我猜是片段搞砸了，因为当我按下第二个选项卡时，第一个选项卡中的数据会更新，依此类推...
I don't what I'm doing wrong, I guess that the fragments are messed up, because when I press the second tab, data from the first tab is updated, and so on ...
谢谢！
推荐答案
我没有使用 CollectionPageAdapter，而是改为使用 ViewPager 并且它有效！
Instead of using CollectionPageAdapter, I changed to use the TabsAdapter class shown in Android documentation of ViewPager and it works!
public class TabsAdapter extends FragmentPagerAdapter
implements ActionBar.TabListener, ViewPager.OnPageChangeListener {
private final Context mContext;
private final ActionBar mActionBar;
private final ViewPager mViewPager;
private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>();
private final List<Fragment> fragments = new ArrayList<Fragment>();
static final class TabInfo {
private final Class<?> clss;
private final Bundle args;
TabInfo(Class<?> _class, Bundle _args) {
clss = _class;
args = _args;
}
}
public TabsAdapter(FragmentActivity activity, ViewPager pager) {
super(activity.getSupportFragmentManager());
mContext = activity;
mActionBar = activity.getActionBar();
mViewPager = pager;
mViewPager.setAdapter(this);
mViewPager.setOnPageChangeListener(this);
}
public void addTab(ActionBar.Tab tab, Class<?> clss, Bundle args) {
TabInfo info = new TabInfo(clss, args);
tab.setTag(info);
tab.setTabListener(this);
mTabs.add(info);
mActionBar.addTab(tab);
notifyDataSetChanged();
}
@Override
public int getCount() {
return mTabs.size();
}
@Override
public int getItemPosition(Object object) {
return POSITION_NONE;
}
@Override
public Fragment getItem(int position) {
TabInfo info = mTabs.get(position);
Fragment fr = Fragment.instantiate(mContext, info.clss.getName(), info.args);
//addFragment (fr, position);
return fr;
}
public void addFragment(Fragment f, int location) {
if (fragments.size() == 0)
fragments.add(f);
else
fragments.add(location, f);
}
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
@Override
public void onPageSelected(int position) {
mActionBar.setSelectedNavigationItem(position);
}
@Override
public void onPageScrollStateChanged(int state) {
}
@Override
public void onTabSelected(Tab tab, android.app.FragmentTransaction ft) {
Object tag = tab.getTag();
for (int i=0; i<mTabs.size(); i++) {
if (mTabs.get(i) == tag) {
updateDatasetMovies (i);
mViewPager.setCurrentItem(i);
}
}
}
@Override
public void onTabReselected(Tab tab, android.app.FragmentTransaction ft) {
// TODO Auto-generated method stub
}
@Override
public void onTabUnselected(Tab tab, android.app.FragmentTransaction ft) {
// TODO Auto-generated method stub
}
public void updateDatasetMovies (int pos)
{
//Let's update the dataset for the selected genre
TabFragment fragment =
(TabFragment) ((FragmentActivity)mContext).getSupportFragmentManager().findFragmentByTag(
"android:switcher:"+R.id.pager+":"+pos);
//TabFragment fragment = (TabFragment) getItem(pos);
if(fragment != null) // could be null if not instantiated yet
{
if(fragment.getView() != null)
{
// no need to call if fragment's onDestroyView()
//has since been called.
fragment.updateDisplay(pos); // do what updates are required
}
}
}
}`
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