我正在使用 FragmentPagerAdapter 和 FragmentActivity 来创建可滑动的片段。
我在那个 pagerAdapter 中的第一个片段看起来像这样。
public class MySummaryFragment extends CommonFragment implements OnPageChangeListener
{
private Context mContext;
private View mMyView;
LinearLayout mDetailLayout;
TextView mDateTxtView;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
System.out.println("onCreateView() Market summary");
mMyView = inflater.inflate(R.layout.my_page_summary_fragment_layout, container,false);
mDetailLayout = (LinearLayout)mMyView.findViewById(R.id.SummaryDetailLayout);
mDateTxtView = (TextView) mMyView.findViewById(R.id.txtDate);
Account_Id = AccountDetails.getInstance(mContext).getClientCodes().get(0);
sendRequest(Account_Id);
return mMyView;
}
@Override
public void onPageSelected(int arg0) {
System.out.println("inside onPageScrollStateChanged()");
System.out.println("mMyView is null ? = "+(mMyView==null));
mDateTxtView = (TextView) mMyView.findViewById(R.id.txtMarketSummaryDate);
Account_Id = AccountDetails.getInstance(mContext).getClientCodes().get(0);
mDateTxtView.setText("");
sendRequest(Account_Id);
}
}
这里的问题是当刷出到 5-6 个片段并刷回第一个片段时，我得到了 NullPointerException。
当我尝试调试时，我发现
mMyView 为空？= 真
为什么这样？
请帮我。
这是我的 Fragment 包含 FragmentPagerAdapter，
public class MyPageDetailViewFragment extends CommonFragment {
private View mView;
Context mContext;
OnPageChangeListener pageChangeListener;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
mView = inflater.inflate(R.layout.my_page_fragments, null);
mContext = getActivity();
setHasOptionsMenu(false);
setupSearchBarComponent();
PagerTabStrip pagerTabStrip = (PagerTabStrip)mView. findViewById(R.id.pager_title_strip);
pagerTabStrip.setDrawFullUnderline(true);
pagerTabStrip.setTabIndicatorColor(Color.BLACK);
/** Getting a reference to the ViewPager defined the layout file */
ViewPager pager = (ViewPager) mView.findViewById(R.id.pager);
/** Getting fragment manager */
FragmentManager fm = ((HomeScreenActivity)mContext).getSupportFragmentManager();
/** Instantiating FragmentPagerAdapter */
final MyFragmentPagerAdapter pagerAdapter = new MyFragmentPagerAdapter(fm);
pager.setAdapter(pagerAdapter);
pager.setCurrentItem(0);
pageChangeListener = new OnPageChangeListener() {
@Override
public void onPageSelected(int selectedIndex) {
System.out.println("selectedIndex = "+selectedIndex);
Object page = pagerAdapter.getItem(selectedIndex);
if( page instanceof OnPageChangeListener){
((OnPageChangeListener) page).onPageSelected(selectedIndex);
}
}
@Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
}
@Override
public void onPageScrollStateChanged(int arg0) {
}
};
pager.setOnPageChangeListener(pageChangeListener);
return mView;
// return super.onCreateView(inflater, container, savedInstanceState);
}
这是我的实现 MyFragmentPagerAdapter，
public class MyFragmentPagerAdapter extends FragmentPagerAdapter {
/** Constructor of the class */
public MyFragmentPagerAdapter(FragmentManager fm) {
super(fm);
}
/** This method will be invoked when a page is requested to create */
@Override
public Fragment getItem(int index) {
System.out.println("getItem = "+index);
Bundle data = new Bundle();
data.putInt("current_page", index + 1);
CommonFragment fragment = getFragment(index);
fragment.setArguments(data);
return fragment;
}
public CommonFragment getFragment(int index) {
CommonFragment fragment = null;
if(fragment == null){
if(index == 0){
fragment = new MySummaryFragment();
}else if(index == 1){
fragment = new FragmentOne();
}else if(index == 4){
fragment = new FragmentFour();
}else if(index == 5){
fragment = new FragmentFive();
}else{
fragment = new MyFragment();
}
}
return fragment;
}
/** Returns the number of pages */
@Override
public int getCount() {
return titles.length;
}
@Override
public CharSequence getPageTitle(int position) {
return titles[position];
}
}