Question

我想在每次向下滑动时刷新RecyclerView。所以我使用SwipeRefreshLayout但现在我也无法刷新RecyclerView。下面是我写的代码：

下面是我的XML文件：fragment_static.xml

<?xml version="1.0" encoding="utf-8"?>
   <android.support.v4.widget.SwipeRefreshLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:id="@+id/container"
    android:layout_height="match_parent">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/recycler_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:scrollbars="vertical" />

</android.support.v4.widget.SwipeRefreshLayout>

下面是我的java文件名：StaticFragment.java

public class StaticFragment extends Fragment  {
    private SwipeRefreshLayout mSwipeRefreshLayout;
    RecyclerView recyclerView ;
    private List<String> fileList = new ArrayList<String>();
    private FileAdapter mAdapter ;

    public StaticFragment() {
    // Required empty public constructor
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View v = inflater.inflate(R.layout.fragment_static, container, false);

        mSwipeRefreshLayout = (SwipeRefreshLayout) v.findViewById(R.id.container);
        mSwipeRefreshLayout.setColorSchemeColors(Color.RED, Color.GREEN, Color.BLUE, Color.YELLOW);
        mSwipeRefreshLayout.setOnRefreshListener(new    SwipeRefreshLayout.OnRefreshListener() {
            @Override
            public void onRefresh() {
                Toast.makeText(getContext(), "Refresh", Toast.LENGTH_SHORT).show();
                new Handler().postDelayed(new Runnable() {
                    @Override
                    public void run() {
                         Fragment frg = null;
                         frg = getFragmentManager().findFragmentByTag("Marker");
                         FragmentTransaction ft = getFragmentManager().beginTransaction();
                        ft.detach(frg);
                        ft.attach(frg);
                        ft.commit();
                        mSwipeRefreshLayout.setRefreshing(false);
                    }
                }, 2000);
            }
         });


         recyclerView = (RecyclerView)v.findViewById(R.id.recycler_view);
         mAdapter = new FileAdapter(fileList);
         RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(getContext().getApplicationContext());

         recyclerView.setLayoutManager(mLayoutManager);
         recyclerView.setItemAnimator(new DefaultItemAnimator());
         recyclerView.setAdapter(mAdapter);

         recyclerView.addOnItemTouchListener(new RecyclerTouchListener(getContext(), recyclerView, new ClickListener() {

             @Override
             public void onClick(View view, int position) {
                 Intent i = new Intent(getContext(),GraphActivityStatic.class);
                 i.putExtra("file_name",fileList.get(position));
                 startActivity(i);
             }

             @Override
             public void onLongClick(View view, int position) {

             }
       }));

    prepareFileData();
    return v;
}

@Override
public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
}

private void prepareFileData() {
    File dir = new File(Environment.getExternalStorageDirectory(),"/PulseData/");
    if(!dir.exists())
        dir.mkdir();
    int position = 0;
    fileList.clear();
    for (File f : dir.listFiles()) {
        if (f.isFile() && f.toString().contains(".txt")) {
            fileList.add(f.getName());
            mAdapter.notifyItemInserted(position++);
        }
    }

}



public interface ClickListener {
    void onClick(View view, int position);

    void onLongClick(View view, int position);
}

public static class RecyclerTouchListener implements RecyclerView.OnItemTouchListener {

    private GestureDetector gestureDetector;
    private StaticFragment.ClickListener clickListener;

    public RecyclerTouchListener(Context context, final RecyclerView recyclerView, final StaticFragment.ClickListener clickListener) {
        this.clickListener = clickListener;
        gestureDetector = new GestureDetector(context, new GestureDetector.SimpleOnGestureListener() {
            @Override
            public boolean onSingleTapUp(MotionEvent e) {
                return true;
            }

            @Override
            public void onLongPress(MotionEvent e) {
                View child = recyclerView.findChildViewUnder(e.getX(), e.getY());
                if (child != null && clickListener != null) {
                    clickListener.onLongClick(child, recyclerView.getChildPosition(child));
                }
            }
        });
    }

    @Override
    public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e) {

        View child = rv.findChildViewUnder(e.getX(), e.getY());
        if (child != null && clickListener != null && gestureDetector.onTouchEvent(e)) {
            clickListener.onClick(child, rv.getChildPosition(child));
        }
        return false;
    }

    @Override
    public void onTouchEvent(RecyclerView rv, MotionEvent e) {
    }

    @Override
    public void onRequestDisallowInterceptTouchEvent(boolean disallowIntercept) {

    }
}
}

它给了我错误：

FATAL EXCEPTION: main
     java.lang.NullPointerException
     at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:726)
     at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1617)
    at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:517)
    at android.os.Handler.handleCallback(Handler.java:605)
    at android.os.Handler.dispatchMessage(Handler.java:92)
    at android.os.Looper.loop(Looper.java:137)
    at android.app.ActivityThread.main(ActivityThread.java:4424)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:511)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:817)
   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:584)
   at dalvik.system.NativeStart.main(Native Method)

Answer 1

SwipeRefresh不会自动刷新/重新加载。您需要在函数中添加一些逻辑。你不需要也不是一个好的实践使用延迟（它仅用于例子和测试）。

mSwipeRefreshLayout.setOnRefreshListener(new    SwipeRefreshLayout.OnRefreshListener() {
            @Override
            public void onRefresh() {
                // Do some logic
                // if (refresh is ok)
                Toast.makeText(getContext(), "Refresh", Toast.LENGTH_SHORT).show();
            }
         });

例如，您可以将要重新加载的所有代码放入绑定中并在SwipeListner中调用绑定：

function void bindMyReclyclerView(){
// bind here your recyclerView
}

mSwipeRefreshLayout.setOnRefreshListener(new    SwipeRefreshLayout.OnRefreshListener() {
                @Override
                public void onRefresh() {
                    bindMyRecyclerView();
                    Toast.makeText(getContext(), "Refresh", Toast.LENGTH_SHORT).show();
                }
             });

我在我的应用中做了类似的事情，请看This class on GitHub。

您也可以重新加载所有活动，但我不推荐这个！（但你可以用于测试）

mSwipeRefreshLayout.setOnRefreshListener(new    SwipeRefreshLayout.OnRefreshListener() {
                    @Override
                    public void onRefresh() {
                        finish();
                        startActivity(getIntent());
                        Toast.makeText(getContext(), "Refresh", Toast.LENGTH_SHORT).show();
                    }
                 });

在android中为RecyclerView实现Swipe刷新

1 个答案: