在ViewPager Android的特定页面中更改ImageView源
我想在视图寻呼机的特定页面中更改imageresource。这就是我所做的 这是onCreate活动在ViewPager Android的特定页面中更改ImageView源,android,imageview,android-viewpager,fragment,adapter,Android,Imageview,Android Viewpager,Fragment,Adapter,我想在视图寻呼机的特定页面中更改imageresource。这就是我所做的 这是onCreate活动 ((PlaceholderFragment)mSectionsPagerAdapter.getItem(0)).updateImage(R.drawable.help1); ((PlaceholderFragment)mSectionsPagerAdapter.getItem(1)).updateImage(R.drawable.help2); (
((PlaceholderFragment)mSectionsPagerAdapter.getItem(0)).updateImage(R.drawable.help1);
((PlaceholderFragment)mSectionsPagerAdapter.getItem(1)).updateImage(R.drawable.help2);
((PlaceholderFragment)mSectionsPagerAdapter.getItem(2)).updateImage(R.drawable.help3);
((PlaceholderFragment)mSectionsPagerAdapter.getItem(3)).updateImage(R.drawable.help4);
这是片段类
public static class PlaceholderFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
/**
* Returns a new instance of this fragment for the given section
* number.
*/
public static PlaceholderFragment newInstance(int sectionNumber) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
public PlaceholderFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_help, container, false);
ImageView imageView = (ImageView) rootView.findViewById(R.id.imageHelp);
imageView.setImageResource(R.drawable.help4);
return rootView;
}
public void updateImage(int image){
ImageView imageView = (ImageView) getView().findViewById(R.id.imageHelp);
imageView.setImageResource(image);
}
}
但不知何故,它仍然给我错误空指针异常。我怎么会错过?
感谢您,请帮助我:)我在这里被困了大约2个小时。显示您的logcat以及它显示空指针异常的行。原因:java.lang.NullPointerException:尝试在空对象引用上调用虚拟方法“android.view.view android.view.view.findViewById(int)”,这是由行引起的ImageView=(ImageView)rootView…我这样做了,使rootView成为全局的,但不知怎么的,它仍然会给我错误,原因是:java.lang.NullPointerException:尝试在空对象引用上调用虚拟方法“android.view.view.view.findViewById(int)”
// declare rootView as global variable
public void updateImage(int image){
ImageView imageView = (ImageView) rootView.findViewById(R.id.imageHelp);
imageView.setImageResource(rootView);
}