尝试将带有FragmentPagerAdapter的ViewPager与所有动态GUI元素(即没有XML)一起使用。是的,我有充分的理由,而不仅仅是因为我觉得它:)在文档中找不到任何表明这不起作用的内容。
工作和不工作之间的唯一区别是使用XML定义ViewGroup(LinearLayout)和ViewPager,而不是在onCreate()中创建。给出以下错误:
java.lang.IllegalArgumentException: No view found for id 0xffffffff for fragment PageFragment{41936480 #0 id=0xffffffff android:switcher:-1:0}
代码:
public class DynoPagerActivity extends FragmentActivity {
private static class MyFragmentPagerAdapter extends FragmentPagerAdapter {
public MyFragmentPagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int index) {
return PageFragment.newInstance("My Message " + index);
}
@Override
public int getCount() {
return 4;
}
}
private ViewPager mViewPager;
private MyFragmentPagerAdapter mMyFragmentPagerAdapter;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
LinearLayout ll = new LinearLayout(this);
ll.setOrientation(LinearLayout.VERTICAL);
setContentView(ll);
mViewPager = new ViewPager(this);
mMyFragmentPagerAdapter = new MyFragmentPagerAdapter(getSupportFragmentManager());
mViewPager.setAdapter(mMyFragmentPagerAdapter);
ll.addView(mViewPager);
//setContentView(ll); tried here as well...
}
}
和
public class PageFragment extends Fragment {
public static PageFragment newInstance(String title) {
PageFragment pageFragment = new PageFragment();
Bundle bundle = new Bundle();
bundle.putString("title", title);
pageFragment.setArguments(bundle);
return pageFragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
// https://android-review.googlesource.com/#/c/31261/ - bug in Support lib
setUserVisibleHint(true);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
TextView textView = new TextView(container.getContext());
textView.setText(getArguments().getString("title"));
return textView;
}
}
似乎是关于如何/何时创建片段,但未能找到连接的问题......
答案 0 :(得分:3)
ViewPager导致对每个“页面”调用findViewById(),该页面试图获取父(ViewPager ID),对于没有设置ID的视图,它总是失败。当您以编程方式创建视图时,它们获得的ID为-1,在浏览Android平台源代码后,始终为findViewByID()返回null / fail。
添加ID可以使其正常工作,但您需要自己安全地管理ID以避免出现问题。将其添加到上面的代码中,使其在onCreate()方法中起作用:
mViewPager.setId(888889);