我使用this tutorial创建标签。 现在我在每个片段中都有一个recyclerview,我想通过mainactivity通知他们。如何在片段中访问适配器?
我用它来调用片段中的refreshData()方法:
TabFragment1 tabFragment = (TabFragment1) getSupportFragmentManager().findFragmentByTag(TabFragment1.class.getSimpleName());
if (tabFragment != null) {
tabFragment.refreshData();
}
但返回null。
mainActivity:
TabLayout tabLayout = (TabLayout) findViewById(R.id.tabLayout);
tabLayout.addTab(tabLayout.newTab().setText("Tab1"));
tabLayout.addTab(tabLayout.newTab().setText("Tab2"));
final PagerAdapter adapter = new PagerAdapter
(getSupportFragmentManager(), tabLayout.getTabCount());
viewPager.setAdapter(adapter);
viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
@Override
public void onTabSelected(TabLayout.Tab tab) {
viewPager.setCurrentItem(tab.getPosition());
}
@Override
public void onTabUnselected(TabLayout.Tab tab) {
}
@Override
public void onTabReselected(TabLayout.Tab tab) {
}
});
PagerAdapter:
public class PagerAdapter extends FragmentStatePagerAdapter {
int mNumOfTabs;
public PagerAdapter(FragmentManager fm, int NumOfTabs) {
super(fm);
this.mNumOfTabs = NumOfTabs;
}
@Override
public Fragment getItem(int position) {
switch (position) {
case 0:
TabFragment1 tab1 = new TabFragment1();
return tab1;
case 1:
TabFragment2 tab2 = new TabFragment2();
return tab2;
case 2:
TabFragment3 tab3 = new TabFragment3();
return tab3;
case 3:
TabFragment4 tab4 = new TabFragment4();
return tab4;
default:
return null;
}
}
@Override
public int getCount() {
return mNumOfTabs;
}
}
myTabFragment之一:
public CardAdapter adapter;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
RecyclerView v = (RecyclerView) inflater.inflate(R.layout.tab_fragment_1, container, false);
SetupRecycleView(v);
return v;
}
public void refreshData() {
adapter.notifyDataSetChanged();
}
void SetupRecycleView(RecyclerView recList) {
recList.setHasFixedSize(true);
LinearLayoutManager llm = new LinearLayoutManager(G.context);
llm.setOrientation(LinearLayoutManager.VERTICAL);
//recList.setLayoutManager(new GridLayoutManager(G.context, 2));
recList.setLayoutManager(llm);
List<StructGhaza> ghazas = StructGhaza.getAllGhaza("2");
adapter = new CardAdapter(ghazas);
recList.setAdapter(adapter);
}
CardAdapter:
public class CardAdapter extends RecyclerView.Adapter<CardAdapter.GhazaViewHolder> {
private List<StructGhaza> ghazas;
public CardAdapter(List<StructGhaza> ghazaList) {
this.ghazas = ghazaList;
}
@Override
public int getItemCount() {
return ghazas.size();
}
@Override
public void onBindViewHolder(GhazaViewHolder ghazaViewHolder, int position) {
StructGhaza ghaza = ghazas.get(position);
ghazaViewHolder.vTitle.setText(ghaza.Name);
//----Load Image
Glide.with(G.context)
.load(ghaza.Aks)
.placeholder(R.drawable.loading_spinner)
.crossFade()
.into(ghazaViewHolder.itemImg);
//---------------
ghazaViewHolder.Rate.setRating(ghaza.Star);
ghazaViewHolder.sampleLayout.setHoverView(ghazaViewHolder.hover);
ghazaViewHolder.sampleLayout.addChildAppearAnimator(ghazaViewHolder.hover, R.id.tvHover, Techniques.FlipInX);
ghazaViewHolder.sampleLayout.addChildDisappearAnimator(ghazaViewHolder.hover, R.id.tvHover, Techniques.FlipOutX);
}
@Override
public GhazaViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
View itemView = LayoutInflater.
from(viewGroup.getContext()).
inflate(R.layout.fragment_carditem, viewGroup, false);
return new GhazaViewHolder(itemView);
}
public static class GhazaViewHolder extends RecyclerView.ViewHolder {
protected TextView vTitle;
protected BlurLayout sampleLayout;
protected View hover;
protected ImageView itemImg;
protected RatingBar Rate;
public GhazaViewHolder(View v) {
super(v);
sampleLayout = (BlurLayout) v.findViewById(R.id.sample);
itemImg = (ImageView) v.findViewById(R.id.item_img);
hover = LayoutInflater.from(G.context).inflate(R.layout.fragment_hover, null);
vTitle = (TextView) v.findViewById(R.id.titleTv);
Rate = (RatingBar) v.findViewById(R.id.rating);
}
}
}
答案 0 :(得分:5)
修改强> 经过多次测试,之前的答案适用于Android&lt; 21,但对于Android&gt; 21它有点奇怪,它似乎没有以同样的方式工作。
最后,我解决了这个问题,它无处不在:
在适配器中:
HashMap<Integer, Fragment> mPageReferenceMap = new HashMap<>();
@Override
public Object instantiateItem(ViewGroup container, int position) {
Fragment fragment = (Fragment) super.instantiateItem(container, position);
mPageReferenceMap.put(position, fragment);
return fragment;
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
super.destroyItem(container, position, object);
mPageReferenceMap.remove(position);
}
public Fragment getFragment(int key) {
return mPageReferenceMap.get(key);
}
你可以在活动中调用getFragment:
int index = viewPager.getCurrentItem();
ViewPagerAdapter adapter = ((ViewPagerAdapter)viewPager.getAdapter());
final YourFragment tabFragment = (YourFragment) adapter.getFragment(index);
以前的答案:
警告:它并不适用于Android&gt; 21
我遇到了同样的问题。最后,我没有使用id或tag。
而不是使用:
CustomFragment customFragment = (CustomFragment) getSupportFragmentManager().findFragmentByTag(getString(R.string.fragment_custo_tag));
使用它:
CustomFragment customFragment = (CustomFragment) getSupportFragmentManager().getFragments().get(0);
获取CustomFragment的实例。
我已将get(0)设置为CustomFragment实例的位置为零。
我在这里发现了这个问题: Set and get using tag a fragment in android