事实证明，这个社区对我的个人和学校项目非常有帮助，所以我决定加入。这是我的第一个问题。目前，我正在暑假空闲时间构建一个 Android 应用程序。我正在尝试在我的应用程序 fragment 之一中实现 SwipeRefreshLayout，但由于未知原因，当我拉动刷新时，我似乎无法让我的 fragment 调用 OnRefresh() 方法。

这是我的 Java 代码:

import android.app.Fragment;
import android.content.Context;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.widget.SwipeRefreshLayout;
import android.support.v4.widget.SwipeRefreshLayout.OnRefreshListener;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import com.parse.FindCallback;
import com.parse.ParseException;
import com.parse.ParseObject;
import com.parse.ParseQuery;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class Notifications extends Fragment implements OnRefreshListener{
    private OnFragmentInteractionListener mListener;
    private RecyclerView mRecyclerView;
    private RecyclerView.Adapter mAdapter;
    private RecyclerView.LayoutManager mLayoutManager;
    private SwipeRefreshLayout swipeLayout;
    private View view;

    public Notifications() {

    }

    public static Notifications newInstance() {
        Notifications fragment = new Notifications();
        Bundle args = new Bundle();
        fragment.setArguments(args);
        return fragment;
    }

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

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        accessDataBase();
        view = inflater.inflate(R.layout.fragment_notifications, container, false);
        swipeLayout = (SwipeRefreshLayout) view.findViewById(R.id.swipeContainer);
        swipeLayout.setOnRefreshListener(this);
        swipeLayout.setColorSchemeColors(android.R.color.holo_green_dark,
                android.R.color.holo_red_dark,
                android.R.color.holo_blue_dark,
                android.R.color.holo_orange_dark);
        return inflater.inflate(R.layout.fragment_notifications, container, false);

    }

    @Override
    public void onRefresh() {
        Log.d("Notifications", "onRefresh called from SwipeRefreshLayout");
    }

    // Used to access my Parse Server database
    public void accessDataBase() {
        ParseQuery query = new ParseQuery("OurPushes");
        query.setCachePolicy(ParseQuery.CachePolicy.CACHE_THEN_NETWORK);
        query.findInBackground(new FindCallback<ParseObject>() {
            public void done(List<ParseObject> objects, ParseException e) {
                if (e == null) {
                    List<String> subject = new ArrayList<>();
                    List<String> body = new ArrayList<>();
                    for (ParseObject pushObject : objects) {
                        if(pushObject.getString("title") != "")
                            subject.add(pushObject.getString("title"));
                        else
                            subject.add("");
                        if(pushObject.getString("alert") != "")
                            body.add(pushObject.getString("alert"));
                        else
                            body.add("");
                    }

                    Collections.reverse(subject);
                    Collections.reverse(body);

                    if(getActivity() != null) {
                        mAdapter = new CustomAdapter(subject, body);
                        mRecyclerView = (RecyclerView) getActivity().findViewById(R.id.rv);
                        mLayoutManager = new LinearLayoutManager(getActivity());
                        mRecyclerView.setLayoutManager(mLayoutManager);
                        mRecyclerView.setAdapter(mAdapter);
                    }

                }
                else {
                    Log.d("Brand", "Error: " + e.getMessage());
                }
            }
        });
    }

    public void onButtonPressed(Uri uri) {
        if (mListener != null) {
            mListener.onFragmentInteraction(uri);
        }
    }

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        if (context instanceof OnFragmentInteractionListener) {
            mListener = (OnFragmentInteractionListener) context;
        } else {
            throw new RuntimeException(context.toString()
                    + " must implement OnFragmentInteractionListener");
        }
    }

    @Override
    public void onDetach() {
        super.onDetach();
        mListener = null;
    }

    public interface OnFragmentInteractionListener {
        void onFragmentInteraction(Uri uri);
    }
}

这是我的 XML 代码 (fragment_notifications.xml):

<android.support.v4.widget.SwipeRefreshLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/swipeContainer"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

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

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

这是我的 Android 显示器上的结果。请注意我在 OnRefresh() 中的 Log.d 语句没有被调用，尽管我在我的 Android 设备上拉动刷新:

06-16 17:57:13.022 2668-2668/xxxxxxx.xxxxxx W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter android.support.graphics.drawable.VectorDrawableCompat.updateTintFilter(android.graphics.PorterDuffColorFilter, android.content.res.ColorStateList, android.graphics.PorterDuff$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable
06-16 17:57:13.314 2668-2718/xxxxxxx.xxxxxx D/OpenGLRenderer: Use EGL_SWAP_BEHAVIOR_PRESERVED: true
06-16 17:57:13.317 2668-2668/xxxxxxx.xxxxxx D/Atlas: Validating map...
06-16 17:57:13.353 2668-2718/xxxxxxx.xxxxxx I/Adreno: EGLInit: QTI Build: 03/04/15, eeab148, 
06-16 17:57:13.365 2668-2718/xxxxxxx.xxxxxx I/OpenGLRenderer: Initialized EGL, version 1.4
06-16 17:57:13.366 2668-2718/xxxxxxx.xxxxxx I/Adreno: GetNativeFormatFromQctPixelFormat: Invalid qct format (611)
06-16 17:57:13.366 2668-2718/xxxxxxx.xxxxxx I/Adreno: GetNativeFormatFromQctPixelFormat: Invalid qct format (611)
06-16 17:57:13.366 2668-2718/xxxxxxx.xxxxxx I/Adreno: GetNativeFormatFromQctPixelFormat: Invalid qct format (611)
06-16 17:57:13.366 2668-2718/xxxxxxx.xxxxxx I/Adreno: GetNativeFormatFromQctPixelFormat: Invalid qct format (611)
06-16 17:57:13.366 2668-2718/xxxxxxx.xxxxxx I/Adreno: GetNativeFormatFromQctPixelFormat: Invalid qct format (612)
06-16 17:57:13.366 2668-2718/xxxxxxx.xxxxxx I/Adreno: GetNativeFormatFromQctPixelFormat: Invalid qct format (612)
06-16 17:57:13.366 2668-2718/xxxxxxx.xxxxxx I/Adreno: GetNativeFormatFromQctPixelFormat: Invalid qct format (612)
06-16 17:57:13.366 2668-2718/xxxxxxx.xxxxxx I/Adreno: GetNativeFormatFromQctPixelFormat: Invalid qct format (612)
06-16 17:57:13.373 2668-2718/xxxxxxx.xxxxxx D/OpenGLRenderer: Enabling debug mode 0
06-16 17:57:13.394 2668-2668/xxxxxxx.xxxxxx E/RecyclerView: No adapter attached; skipping layout
06-16 17:57:13.445 2668-2719/xxxxxxx.xxxxxx I/OpenGLRenderer: WorkerThread::readyToRun:hwuiTask1
06-16 17:58:46.962 2668-4140/xxxxxxx.xxxxxx I/OpenGLRenderer: WorkerThread::readyToRun:hwuiTask2

我知道你们中的一些人可能会提到，我知道 Parse 即将结束。我正在使用解析服务器。我的解析服务器托管在 Heroku 上，而不是 Parse.com。

在此先感谢您的帮助。如果您需要任何其他信息，请询问。

最佳答案

在 onCreateView 中，您将返回一个与您使用 OnRefreshListener 设置的 View 不同的 View 。请注意，您调用了 inflater.inflate(...) 两次，创建了两个单独的 View 。试试这个:

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    accessDataBase();
    view = inflater.inflate(R.layout.fragment_notifications, container, false);
    swipeLayout = (SwipeRefreshLayout) view.findViewById(R.id.swipeContainer);
    swipeLayout.setOnRefreshListener(this);
    swipeLayout.setColorSchemeColors(android.R.color.holo_green_dark,
            android.R.color.holo_red_dark,
            android.R.color.holo_blue_dark,
            android.R.color.holo_orange_dark);
    return view;

}

关于java - Android:SwipeRefreshLayout 不会调用 OnRefresh()，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/37870096/