我是Android的初学者。当我在带有TabLayout的片段中使用ListView时，一切都很好。 enter image description here 现在我想用TabLayout在Fragment中实现带有CardView行的RecyclerView。 但是，当使用带有CardView的RecyclerView时，片段中没有显示任何内容。为什么？ enter image description here
请帮忙！提前谢谢！
这是我的代码：
MainActivity.java：
make -j nactivity_main.xml中：
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// 关联ViewPager和SampleFragmentPagerAdapter,配置tabs用以下两个步骤:
// ① Get the ViewPager and set it's PagerAdapter so that it can display items
ViewPager viewPager=(ViewPager) findViewById(R.id.viewpager);
viewPager.setAdapter(new SampleFragmentPagerAdapter(getSupportFragmentManager(),MainActivity.this));
// ② 为了关联pager和tabs，在TabLayout中设置ViewPager
TabLayout tabLayout=(TabLayout) findViewById(R.id.sliding_tabs);
tabLayout.setupWithViewPager(viewPager);
}
public class SampleFragmentPagerAdapter extends FragmentPagerAdapter{
final int PAGE_COUNT=3;
private String[] tabTitles={"知乎日报","果壳精选","豆瓣一刻"};
private Context context;
public SampleFragmentPagerAdapter(FragmentManager fm, Context context) {
super(fm);
this.context = context;
}
@Override
public int getCount() {
return PAGE_COUNT;
}
@Override
public Fragment getItem(int position) {
return PageFragment.newInstance(position+1);
}
@Override
public CharSequence getPageTitle(int position) {
return tabTitles[position];
}
}
}
PageFragment.java：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.sherrywong.stonedaily.MainActivity">
<android.support.design.widget.TabLayout
android:id="@+id/sliding_tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:tabMode="fixed"
app:tabGravity="fill">
</android.support.design.widget.TabLayout>
<android.support.v4.view.ViewPager
android:id="@+id/viewpager"
android:layout_width="match_parent"
android:layout_height="0px"
android:layout_weight="1"
android:background="@android:color/white">
</android.support.v4.view.ViewPager>
</LinearLayout>
MyAdapter.java：
public class PageFragment extends Fragment{
private String TAG=PageFragment.class.getName(); // 打印log时使用
private static final String ARG_PAGE = "ARG_PAGE";
private int mPage;
private RecyclerView recyclerView;
private MyAdapter myAdapter;
private OnFragmentInteractionListener mListener;
public PageFragment() {
// Required empty public constructor
}
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
* @param page
* @return A new instance of fragment PageFragment.
*/
public static PageFragment newInstance(int page) {
Bundle args=new Bundle();
args.putInt(ARG_PAGE,page);
PageFragment fragment=new PageFragment();
fragment.setArguments(args);
return fragment;
}
//Store instance variables based on arguments passed
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.i(TAG,"---------onCreate");
if (getArguments() != null) {
mPage=getArguments().getInt(ARG_PAGE);
}
}
/**
* Define fragment layout
* @param inflater
* @param container
* @param savedInstanceState
* @return View
*/
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view=inflater.inflate(R.layout.fragment_page,container,false);
// 获取RecyclerView
recyclerView=(RecyclerView) view.findViewById(R.id.recycler_list);
// 设置布局管理器
recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
// 设置ItemAnimator
recyclerView.setItemAnimator(new DefaultItemAnimator());
// 设置固定大小
recyclerView.setHasFixedSize(true);
// 初始化自定义适配器
String[] list={"class 1","class 2","class 3","class 4","class 5","class 6","class 7","class 8"};
myAdapter=new MyAdapter(getActivity(),getData(list));
// 为recyclerView设置适配器
recyclerView.setAdapter(myAdapter);
Log.i(TAG,"---------onCreateView");
return view;
}
public interface OnFragmentInteractionListener {
void onFragmentInteraction(Uri uri);
}
/*
@Override
public void onListItemClick(ListView l, View v, int position, long id) {
super.onListItemClick(l, v, position, id);
System.out.println(l.getChildAt(position));
HashMap<String,String> view=(HashMap<String, String>) l.getItemAtPosition(position);
System.out.println(view.get("title").toString()+"+++++++++title");
Toast.makeText(getActivity(),TAG+l.getItemIdAtPosition(position),Toast.LENGTH_SHORT).show();
System.out.println(v);
System.out.println(position);
}
*/
private List<HashMap<String,String>> getData(String[] args){
List<HashMap<String,String>> list=new ArrayList<>();
for (int i=0;i<args.length;i++){
HashMap<String,String> map=new HashMap<>();
map.put("title",args[i]);
map.put("image","http://img3.hao123.com/data/1_8583424a3f55c06ebeafce438a637c0d_0");
list.add(map);
}
return list;
}
@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
Log.i(TAG,"-----------onActivityCreated");
}
}
fragment_page.xml：
public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder> {
private Context context;
private List<HashMap<String,String>> dataSet;
public MyAdapter(Context context,List<HashMap<String,String>> dataSet){
this.context=context;
this.dataSet=dataSet;
}
// Provide a reference to the views for each data item
// Complex data items may need more than one view per item, and
// you provide access to all the views for a data item in a view holder
public static class MyViewHolder extends RecyclerView.ViewHolder{
// each data item is just a string in this case.
public TextView textView;
public ImageView imageView;
public MyViewHolder(View view){
super(view);
textView=(TextView) view.findViewById(R.id.itemTitle);
imageView=(ImageView) view.findViewById(R.id.itemImage);
}
}
@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
// 给ViewHolder设置布局文件
View view= LayoutInflater.from(parent.getContext()).inflate(R.layout.card_item,parent,false);
return new MyViewHolder(view);
}
@Override
public void onBindViewHolder(MyViewHolder holder, int position) {
// 给ViewHolder设置元素
Picasso.with(context).load(dataSet.get(position).get("image")).into(holder.imageView);
holder.textView.setText(dataSet.get(position).get("title"));
}
@Override
public int getItemCount() {
// 返回数据总数
return dataSet==null?0:dataSet.size();
}
}
card_item.xml：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.sherrywong.stonedaily.PageFragment">
<android.support.v7.widget.RecyclerView
android:id="@+id/recycler_list"
android:layout_width="match_parent"
android:layout_height="match_parent">
</android.support.v7.widget.RecyclerView>
</RelativeLayout>
答案 0 :(得分：0)
Picasso.with(context).load(dataSet.get(position).get("image")).into(holder.imageView);
//将上面的代码行改为
Picasso.with(holder.imageView.getContext()).load(dataSet.get(position).get("image")).into(holder.imageView);