实例化FragmentPagerAdapter时,将ArrayList作为参数传递给适配器构造函数
mSectionsPagerAdapter = new
SectionsPagerAdapter(getSupportFragmentManager(), titles);
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.container);
mViewPager.setAdapter(mSectionsPagerAdapter);
在适配器中,使用引用,并从数组中获取字符串,如
public class SectionsPagerAdapter extends FragmentPagerAdapter {
private ArrayList<String> strings;
public SectionsPagerAdapter(FragmentManager fm, ArrayList<String> strings) {
super(fm);
this.strings = strings;
}
@Override
public Fragment getItem(int position) {
return PlaceholderFragment.newInstance(position + 1, strings.get(position + 1));
}
@Override
public int getCount() {
return strings.size();
}
}
最后,在Fragment类中,将其作为参数传递,并从onCreate方法中作为全局变量获取
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";
private String title;
public PlaceholderFragment() {
}
/**
* Returns a new instance of this fragment for the given section
* number.
*/
public static PlaceholderFragment newInstance(int sectionNumber, String title) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
args.putString("key", title);
fragment.setArguments(args);
return fragment;
}
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
title = getArguments().getString("key");
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_my_gallery,
container, false);
TextView textView = (TextView)
rootView.findViewById(R.id.section_label);
textView.setText(getString(R.string.section_format,
getArguments().getInt(ARG_SECTION_NUMBER)));
return rootView;
}
}
笔记为了更好地控制代码,如果片段数量有限,应该使用
switch
陈述使命感
position + 1
在您的情况下,当超过数组的索引时,适配器可能会引发nullpointerexception。您可以使用
viewPager.setCurrentItem(position);
,带有switch语句的FragmentPagerAdapter示例如下所示
@Override
public Fragment getItem(int position) {
switch (position) {
case 0:
return PlaceholderFragment.newInstance(position, strings.get(position));
case 1:
return PlaceholderFragment.newInstance(position, strings.get(position));
case 2:
return PlaceholderFragment.newInstance(position, strings.get(position));
default:
return something...
}
}