FragmentPagerAdapter fragmentPagerAdapter = (FragmentPagerAdapter) mViewPager.getAdapter();
for(int i = 0; i < fragmentPagerAdapter.getCount(); i++) {
Fragment viewPagerFragment = fragmentPagerAdapter.getItem(i);
if(viewPagerFragment != null) {
// Do something with your Fragment
// Check viewPagerFragment.isResumed() if you intend on interacting with any views.
}
}
FragmentPagerAdapter fragmentPagerAdapter = (FragmentPagerAdapter) mViewPager.getAdapter();
for(int i = 0; i < fragmentPagerAdapter.getCount(); i++) {
String name = makeFragmentName(mViewPager.getId(), i);
Fragment viewPagerFragment = getChildFragmentManager().findFragmentByTag(name);
// OR Fragment viewPagerFragment = getFragmentManager().findFragmentByTag(name);
if(viewPagerFragment != null) {
// Do something with your Fragment
if (viewPagerFragment.isResumed()) {
// Interact with any views/data that must be alive
}
else {
// Flag something for update later, when this viewPagerFragment
// returns to onResume
}
}
}
public class MyPagerAdapter extends FragmentStatePagerAdapter {
SparseArray<Fragment> registeredFragments = new SparseArray<Fragment>();
public MyPagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public int getCount() {
return ...;
}
@Override
public Fragment getItem(int position) {
return MyFragment.newInstance(...);
}
@Override
public Object instantiateItem(ViewGroup container, int position) {
Fragment fragment = (Fragment) super.instantiateItem(container, position);
registeredFragments.put(position, fragment);
return fragment;
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
registeredFragments.remove(position);
super.destroyItem(container, position, object);
}
public Fragment getRegisteredFragment(int position) {
return registeredFragments.get(position);
}
}
public Fragment getActiveFragment(int position) {
String name = MyPagerAdapter.makeFragmentName(position);
return getSupportFragmentManager().findFragmentByTag(name);
}
在适配器中:
public class MyPagerAdapter extends FragmentStatePagerAdapter {
private final ActionBar actionBar;
private final FragmentManager fragmentManager;
public MyPagerAdapter(FragmentManager fragmentManager, com.actionbarsherlock.app.ActionBarActionBar mActionBar) {super(fragmentManager);
this.actionBar = mActionBar;
this.fragmentManager = fragmentManager;
}
@Override
public Fragment getItem(int position) {
getSupportFragmentManager().beginTransaction().add(mTchatDetailsFragment, makeFragmentName(position)).commit();
return (Fragment)this.actionBar.getTabAt(position);
}
@Override
public int getCount() {
return this.actionBar.getTabCount();
}
@Override
public CharSequence getPageTitle(int position) {
return this.actionBar.getTabAt(position).getText();
}
private static String makeFragmentName(int viewId, int index) {
return "android:fragment:" + index;
}
}
@Override
onCreate(){
//initialise the list of fragments
fragments = new Vector<Fragment>();
//fill up the list with out fragments
fragments.add(Fragment.instantiate(this, MainFragment.class.getName()));
fragments.add(Fragment.instantiate(this, MenuFragment.class.getName()));
fragments.add(Fragment.instantiate(this, StoresFragment.class.getName()));
fragments.add(Fragment.instantiate(this, AboutFragment.class.getName()));
fragments.add(Fragment.instantiate(this, ContactFragment.class.getName()));
//Set up the pager
pager = (ViewPager)findViewById(R.id.pager);
pager.setAdapter(new MyFragmentPagerAdapter(getSupportFragmentManager(), fragments));
pager.setOffscreenPageLimit(4);
}
那么这个就可以叫做
public Fragment getFragment(ViewPager pager){
Fragment theFragment = fragments.get(pager.getCurrentItem());
return theFragment;
}
然后我可以把它扔进if语句中只有在正确的片段上才会运行
Fragment tempFragment = getFragment();
if(tempFragment == MyFragmentNo2.class){
MyFragmentNo2 theFrag = (MyFragmentNo2) tempFragment;
//then you can do whatever with the fragment
theFrag.costomFunction();
}
/**
* @param containerViewId the ViewPager this adapter is being supplied to
* @param id pass in getItemId(position) as this is whats used internally in this class
* @return the tag used for this pages fragment
*/
public static String makeFragmentName(int containerViewId, long id) {
return "android:switcher:" + containerViewId + ":" + id;
}
/**
* @return may return null if the fragment has not been instantiated yet for that position - this depends on if the fragment has been viewed
* yet OR is a sibling covered by {@link android.support.v4.view.ViewPager#setOffscreenPageLimit(int)}. Can use this to call methods on
* the current positions fragment.
*/
public @Nullable Fragment getFragmentForPosition(int position)
{
String tag = makeFragmentName(mViewPager.getId(), getItemId(position));
Fragment fragment = getSupportFragmentManager().findFragmentByTag(tag);
return fragment;
}
public Fragment getItem(int position) {
Fragment fragment = null;
if (position == 0) {
fragment = FragmentOne.newInstance();
mViewPager.setTag(R.integer.page1,fragment);
}
else if (position == 1) {
fragment = FragmentTwo.newInstance();
mViewPager.setTag(R.integer.page2,fragment);
} else if (position == 2) {
fragment = FragmentThree.newInstance();
mViewPager.setTag(R.integer.page3,fragment);
}
return fragment;
}
然后在activity中写这个函数来获取片段引用:
private Fragment getFragmentByPosition(int position) {
Fragment fragment = null;
switch (position) {
case 0:
fragment = (Fragment) mViewPager.getTag(R.integer.page1);
break;
case 1:
fragment = (Fragment) mViewPager.getTag(R.integer.page2);
break;
case 2:
fragment = (Fragment) mViewPager.getTag(R.integer.page3);
break;
}
return fragment;
}
通过调用上面的函数来获取片段引用,然后将其转换为自定义片段:
Fragment fragment = getFragmentByPosition(position);
if (fragment != null) {
FragmentOne fragmentOne = (FragmentOne) fragment;
}