我想从我的 FragmentPagerAdapter 中分离一个片段，但它似乎不起作用。这是我从原始代码中复制的 pageradapter 类：
public class PagerAdapter1 extends FragmentPagerAdapter {
private List<String> fragments;
private static final String TAG = "FragmentPagerAdapter";
private static final boolean DEBUG = true;
private Fragment mCurrentPrimaryItem = null;
private final FragmentManager mFragmentManager;
private FragmentTransaction mCurTransaction = null;
/**
* @param fm
* @param fragments2
*/
public PagerAdapter1(FragmentManager fm, List<String> fragments2) {
super(fm);
mFragmentManager=fm;
this.fragments = fragments2;
}
/* (non-Javadoc)
* @see android.support.v4.app.FragmentPagerAdapter#getItem(int)
*/
@Override
public Fragment getItem(int position) {
//return this.fragments.get(position);
return Fragment.instantiate(ViewPagerActivity.context, fragments.get(position));
}
/* (non-Javadoc)
* @see android.support.v4.view.PagerAdapter#getCount()
*/
@Override
public int getCount() {
return this.fragments.size();
}
/**
* Return the Fragment associated with a specified position.
*/
@Override
public void startUpdate(ViewGroup container) {
}
@Override
public Object instantiateItem(ViewGroup container, int position) {
Log.i("asasd", "asdasdasdasdasd");
if (mCurTransaction == null) {
mCurTransaction = mFragmentManager.beginTransaction();
}
final long itemId = getItemId(position);
// Do we already have this fragment?
String name = makeFragmentName(container.getId(), itemId);
Fragment fragment = mFragmentManager.findFragmentByTag(name);
if (fragment != null) {
if (DEBUG) Log.v(TAG, "Attaching item #" + itemId + ": f=" + fragment);
mCurTransaction.attach(fragment);
} else {
fragment = getItem(position);
if (DEBUG) Log.v(TAG, "Adding item #" + itemId + ": f=" + fragment);
mCurTransaction.add(container.getId(), fragment,
makeFragmentName(container.getId(), itemId));
// Log.i("asdJANIANI", " " + getFragmentTag(container.getId(),0));
//Log.i("JANI", " " + getItem(0));
}
if (fragment != mCurrentPrimaryItem) {
fragment.setMenuVisibility(false);
fragment.setUserVisibleHint(false);
}
**destroyItem(container,0,getItem(0));**
return fragment;
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
if (mCurTransaction == null) {
mCurTransaction = mFragmentManager.beginTransaction();
}
if (DEBUG) Log.v(TAG, "Detaching item #" + getItemId(position) + ": f=" + object
+ " v=" + ((Fragment)object).getView());
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;
}
if (position == 0){
this.notifyDataSetChanged();
}
}
@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>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
*/
public long getItemId(int position) {
return position;
}
private static String makeFragmentName(int viewId, long id) {
return "android:switcher:" + viewId + ":" + id;
}
}
我只改变了一件事，我destroyItem()在 instantiateItem() 方法中实现了一个方法，因为我想在每次实例化片段时分离片段（位置 0）。我没有收到任何错误，它只是没有分离。为什么？
先感谢您！