Question

我正在构建一个应用程序，使用tablayout从网站上提取rss，但我有一个问题：错误：

'com.joyfm96.joy.BusinessFragment'中的'BusinessFragment（android.content.Context，android.support.v7.widget.RecyclerView）'无法应用于'（）'

这是我的TabFragment.java

package com.joyfm96.joy;

import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.design.widget.TabLayout;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.support.v4.app.Fragment;


import com.joyfm96.joy.R;

public class TabFragment extends Fragment {

    public static TabLayout tabLayout;
    public static ViewPager viewPager;
    public static int int_items = 4 ;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        View v =  inflater.inflate(R.layout.tab_layout, container, false);
        tabLayout = (TabLayout) v.findViewById(R.id.tabs);
        viewPager = (ViewPager) v.findViewById(R.id.viewpager);

        viewPager.setAdapter(new MyAdapter(getChildFragmentManager()));

        tabLayout.post(new Runnable() {
            @Override
            public void run() {
                tabLayout.setupWithViewPager(viewPager);
            }
        });

        return v;

    }

    class MyAdapter extends FragmentPagerAdapter {

        public MyAdapter(FragmentManager fm) {
            super(fm);
        }

        @Override
        public Fragment getItem(int position)
        {
            switch (position){
                case 0 : return new EntertainmentFragment();
                case 1 : return new PoliticsFragment();
                case 2 : return new BusinessFragment();
                case 3 : return new SportsFragment();
            }
            return null;
        }

        @Override
        public int getCount() {

            return int_items;

        }

        @Override
        public CharSequence getPageTitle(int position) {

            switch (position){
                case 0 :
                    return getResources().getString(R.string.tab1);
                case 1 :
                    return getResources().getString(R.string.tab2);
                case 2 :
                    return getResources().getString(R.string.tab3);
                case 3 :
                    return getResources().getString(R.string.tab4);
            }
            return null;
        }
    }

}

这是EntertainmentFragment.java

package com.joyfm96.joy;

import android.app.ProgressDialog;
import android.content.Context;
import android.os.AsyncTask;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

public class EntertainmentFragment extends AsyncTask<Void, Void, Void> {
    Context context;
    String address = "http://joyfm96.com/category/entertainment/feed/";
    ProgressDialog progressDialog;
    ArrayList<FeedItem>feedItems;
    RecyclerView recyclerView;
    URL url;
    public EntertainmentFragment(Context context,RecyclerView recyclerView) {
        this.recyclerView=recyclerView;
        this.context = context;
        progressDialog = new ProgressDialog(context);
        progressDialog.setMessage("Loading...");
    }

    @Override
    protected void onPreExecute() {
        progressDialog.show();
        super.onPreExecute();
    }

    @Override
    protected void onPostExecute(Void aVoid) {
        super.onPostExecute(aVoid);
        progressDialog.dismiss();
        MyAdapter adapter=new MyAdapter(context,feedItems);
        recyclerView.setLayoutManager(new LinearLayoutManager(context));
        recyclerView.addItemDecoration(new VerticalSpace(50));
        recyclerView.setAdapter(adapter);

    }

    @Override
    protected Void doInBackground(Void... params) {
        ProcessXml(Getdata());

        return null;
    }

    private void ProcessXml(Document data) {
        if (data != null) {
            feedItems=new ArrayList<>();
            Element root = data.getDocumentElement();
            Node channel = root.getChildNodes().item(1);
            NodeList items = channel.getChildNodes();
            for (int i = 0; i < items.getLength(); i++) {
                Node cureentchild = items.item(i);
                if (cureentchild.getNodeName().equalsIgnoreCase("item")) {
                    FeedItem item=new FeedItem();
                    NodeList itemchilds = cureentchild.getChildNodes();
                    for (int j = 0; j < itemchilds.getLength(); j++) {
                        Node cureent = itemchilds.item(j);
                        if (cureent.getNodeName().equalsIgnoreCase("title")){
                            item.setTitle(cureent.getTextContent());
                        }else if (cureent.getNodeName().equalsIgnoreCase("description")){
                            item.setDescription(cureent.getTextContent());
                        }else if (cureent.getNodeName().equalsIgnoreCase("pubDate")){
                            item.setPubDate(cureent.getTextContent());
                        }else if (cureent.getNodeName().equalsIgnoreCase("link")){
                            item.setLink(cureent.getTextContent());
                        }else if (cureent.getNodeName().equalsIgnoreCase("media:thumbnail")){
                            //this will return us thumbnail url
                            String url=cureent.getAttributes().item(0).getTextContent();
                            item.setThumbnailUrl(url);
                        }
                    }
                    feedItems.add(item);





                }
            }
        }
    }

    public Document Getdata() {
        try {
            url = new URL(address);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setRequestMethod("GET");
            InputStream inputStream = connection.getInputStream();
            DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();
            DocumentBuilder builder = builderFactory.newDocumentBuilder();
            Document xmlDoc = builder.parse(inputStream);
            return xmlDoc;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }

    }

}

我该如何修复此错误？感谢

Answer 1

从日志中看起来您正在尝试使用默认构造函数创建对象，但是您在类文件中没有要在选项卡中创建对象的默认构造函数。

为这些文件添加默认构造函数或在Tab类中创建对象时使用BusinesFragment，EmployeeFragment等中的对象

（android.content.Context，android.support.v7.widget.RecyclerView）'in'com.joyfm96.joy.EntertainmentFragment'无法应用于'（）'

1 个答案: