我使用<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/raphael/2.1.0/raphael-min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/morris.js/0.5.1/morris.min.js"></script>
<link href="//cdnjs.cloudflare.com/ajax/libs/morris.js/0.5.1/morris.css" rel="stylesheet" />
<div id="samplechart"></div>
<a href="#" onclick="getMorrisOffline();">Refresh Morris</a> + TabLayout来显示几个标签。根据服务器的响应，我想创建两种可能的场景：第一种是三个选项卡，第二种只有两种，＆＃39;删除＆＃39;位于0的标签。
因为我正在删除＆＃39;第一个选项卡，依赖于位置来执行与特定片段相关的任何事情的所有方法都会过时，并且很可能无法通过ViewPager检查。
例如，这是instanceof中的getItem，目前还没有处理第二种情况：
FragmentStatePagerAdapter @Override
public Fragment getItem(int position) {
AbstractFragment fragment;
switch (position) {
case 0:
fragment = new MainFragment();
break;
case 1:
fragment = new MessagesFragment();
break;
case 2:
fragment = new SearchFragment();
break;
default:
return null;
}
return fragment;
}
中的监听器示例（检查将在第二种情况下失败）：
MainActivity我唯一的想法是检查Fragment fragment = viewPagerAdapter.getRegisteredFragment(2);
if (fragment instanceof SearchFragment) {
((SearchFragment)fragment).doStuff();
}
中每个监听器中的服务器响应（即，是否有两个或三个选项卡）以及MainActivity中的每个监听器，这在我看来是一个可怕的解决方案。有没有更好的方法来解决这个问题？
答案 0 :(得分：1)
由于只有很少的标签，一个好的方法是制作一个你想要展示的片段列表：
List<AbstractFragment> fragments = new ArrayList<>();
if (showFirstTab) {
fragments.add(new MainFragment());
}
fragments.add(new MessagesFragment());
fragments.add(new SearchFragment());
然后在getItem方法，这样做：
@Override
public Fragment getItem(int position) {
if (fragments.size() > position) {
return fragments.get(position);
}
return null;
}
当您需要获取特定片段时，您可以获取fragments列表并迭代测试instanceof。
让我知道它是否对你有所帮助。
答案 1 :(得分：0)
您可以使用自定义片段寻呼机适配器来逐位获取
#2-Aggr现在只需按public abstract class FragmentPagerAdapter extends PagerAdapter {
private static final String TAG = "FragmentPagerAdapter";
private static final boolean DEBUG = false;
private final FragmentManager mFragmentManager;
private FragmentTransaction mCurTransaction = null;
private Fragment mCurrentPrimaryItem = null;
private String mAdapterClassName;
protected FragmentPagerAdapter(FragmentManager fm, String adapterClassName) {
mFragmentManager = fm;
mAdapterClassName = adapterClassName;
}
/**
* Return the Fragment associated with a specified position.
*/
protected abstract Fragment getItem(int position);
@Override
public void startUpdate(ViewGroup container) {
}
@Override
public Object instantiateItem(ViewGroup container, int position) {
if (mCurTransaction == null) {
mCurTransaction = mFragmentManager.beginTransaction();
}
// Do we already have this fragment?
String name = makeFragmentTag(position);
Fragment fragment = mFragmentManager.findFragmentByTag(name);
if (fragment != null) {
mCurTransaction.attach(fragment);
} else {
fragment = getItem(position);
mCurTransaction.add(container.getId(), fragment,
makeFragmentTag(position));
}
if (fragment != mCurrentPrimaryItem) {
fragment.setMenuVisibility(false);
fragment.setUserVisibleHint(false);
}
return fragment;
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
if (mCurTransaction == null) {
mCurTransaction = mFragmentManager.beginTransaction();
}
mCurTransaction.detach((Fragment) object);
}
@Override
public void setPrimaryItem(ViewGroup container, int position, Object object) {
Fragment fragment = (Fragment) object;
if (fragment != mCurrentPrimaryItem) {
if (mCurrentPrimaryItem != null) {
mCurrentPrimaryItem.setMenuVisibility(false);
mCurrentPrimaryItem.setUserVisibleHint(false);
}
if (fragment != null) {
fragment.setMenuVisibility(true);
fragment.setUserVisibleHint(true);
}
mCurrentPrimaryItem = fragment;
}
}
@Override
public void finishUpdate(ViewGroup container) {
if (mCurTransaction != null) {
mCurTransaction.commitAllowingStateLoss();
mCurTransaction = null;
mFragmentManager.executePendingTransactions();
}
}
@Override
public boolean isViewFromObject(View view, Object object) {
return ((Fragment) object).getView() == view;
}
@Override
public Parcelable saveState() {
return null;
}
@Override
public void restoreState(Parcelable state, ClassLoader loader) {
}
/**
* Return a unique identifier for the item at the given position.
* <p/>
* <p>The default implementation returns the given position.
* Subclasses should override this method if the positions of items can change.</p>
*
* @param position Position within this adapter
* @return Unique identifier for the item at position
*/
private long getItemId(int position) {
return position;
}
public String makeFragmentTag(int position) {
return "purplle:switcher:" + mAdapterClassName + ":" + position;
}
public static String makeFragmentTag(int position,String adapterClassName) {
return "purplle:switcher:" + adapterClassName + ":" + position;
}
}
获取活动中的片段。
FragmentPagerAdapter