我看到了与我的问题相关的帖子,但它没有解决我的问题。 我正在尝试使用3个片段创建一个滑动视图。 在主片段中,我有以下内容:
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View vue = inflater.inflate(R.layout.fragment_conversions, container, false);
ConversionsPagerAdapter cPageAdapter = new ConversionsPagerAdapter(getActivity().getSupportFragmentManager());
ViewPager vp = vue.findViewById(R.id.conversionsPager);
cPageAdapter.getItem(0);
vp.setAdapter(cPageAdapter);
Button convKmhKts = (Button) vue.findViewById(R.id.convKmhKts);
convKmhKts.setText("...");
...
这是我的FragmentStatePagerAdapter类:
public class ConversionsPagerAdapter extends FragmentStatePagerAdapter{
public ConversionsPagerAdapter(FragmentManager fm) {
super(fm);
Log.i("ARKA", "FragmentStatePagerAdapter CONSTRUCTOR");
}
@Override
public Fragment getItem(int i) {
return ConversionFragment.newInstance(i);
}
@Override
public int getCount() {
return 1;
}
}
最后是显示选项卡的片段(Fragment):
public class ConversionFragment extends Fragment {
public static final String ID_CONVERSION = "id_conversion";
public static ConversionFragment newInstance(int pos) {
ConversionFragment stf = new ConversionFragment();
Bundle args = new Bundle();
args.putInt("pos", pos);
stf.setArguments(args);
return stf;
}
public ConversionFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
// The last two arguments ensure LayoutParams are inflated
// properly.
Bundle args = getArguments();
int idConversion = args.getInt(ID_CONVERSION);
Log.i("idConversion", String.valueOf(idConversion));
int idVue;
switch (idConversion){
case 0: idVue = R.layout.fragment_conversions_vitesse;
break;
case 1: idVue = R.layout.fragment_conversions_vitesse;
default: idVue = R.layout.fragment_conversions_vitesse;
break;
}
View rootView = inflater.inflate(idVue, null);
return rootView;
}
}
事实上,getItem()从未被调用。 我尝试通过getChildFragmentManager()更改getActivity().getSupportFragmentManager(),但似乎这不是正确的方法... 当我试图访问我的按钮时,我得到了以下错误: java.lang.NullPointerException: 尝试在空对象引用上调用虚拟方法'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' 出错行是我使用按钮的那一行。