java - 使适配器变量时出错 GetData()

Question

我正在观看来自 Slidenerd 的关于在 Android 上制作 Recycle View 的 Android 教程。这个链接:https://www.youtube.com/watch?v=OoCySqneJno .

当我制作适配器变量时，出现错误。这是我的完整代码:

NavigationDrawerFragment.java

package com.balinez.wdharmana.doahindu;


import android.content.Context;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.support.v7.widget.Toolbar;


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


/**
 * A simple {@link Fragment} subclass.
 */
public class NavigationDrawerFragment extends Fragment {

    private RecyclerView recyclerView;

    public static final String PREF_FILE_NAME="testpref";
    public static final String KEY_USER_LEARNED_DRAWER="user_learned_drawer";
    private ActionBarDrawerToggle mDrawerToggle;
    private DrawerLayout mDrawerLayout;
    private BalinezAdapter adapter;
    private boolean mUserLearnedDrawer;
    private boolean mFromSavedInstanceState;
    private View containerView;

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

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mUserLearnedDrawer=Boolean.valueOf(readFromPreferences(getActivity(), KEY_USER_LEARNED_DRAWER,"false"));

        if(savedInstanceState!=null) {
            mFromSavedInstanceState=true;
        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View layout = inflater.inflate(R.layout.fragment_navigation_drawer, container, false);
        recyclerView=(RecyclerView) layout.findViewById(R.id.drawer_list);
        adapter = new BalinezAdapter(getActivity(),getData());
        recyclerView.setAdapter(adapter);
        recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));

        return layout;
    }

    public static List<Information> getData() {
        List<Information> data = new ArrayList<>();
        int[] icons = {R.drawable.ic_bookmark1, R.drawable.ic_bookmark1};
        String[] titles={"Doa Sehari-Hari", "Doa Sembahyang"};

        for (int i=0; i<titles.length && i<icons.length; i++) {
            Information current = new Information();
            current.iconId = icons[i];
            current.title = titles[i];
            data.add(current);
        }
        return data;
    }



    public void setUp(int fragmentId, DrawerLayout drawerLayout, Toolbar toolbar) {
        containerView = getActivity().findViewById(fragmentId);
        mDrawerLayout = drawerLayout;
        mDrawerToggle = new ActionBarDrawerToggle(getActivity(), drawerLayout, toolbar, R.string.drawer_open, R.string.drawer_close) {

            @Override
            public void onDrawerOpened(View drawerView) {
                super.onDrawerOpened(drawerView);
                if(!mUserLearnedDrawer) {
                    mUserLearnedDrawer=true;
                    saveToPreferences(getActivity(),KEY_USER_LEARNED_DRAWER,mUserLearnedDrawer+"");
                }
                getActivity().invalidateOptionsMenu();
            }

            @Override
            public void onDrawerClosed(View drawerView) {
                super.onDrawerClosed(drawerView);
                getActivity().invalidateOptionsMenu();
            }
        };

        if(!mUserLearnedDrawer && !mFromSavedInstanceState) {
            mDrawerLayout.openDrawer(containerView);
        }

        mDrawerLayout.setDrawerListener(mDrawerToggle);
        mDrawerLayout.post(new Runnable() {
            @Override
            public void run() {
                mDrawerToggle.syncState();
            }
        });

    }

    public static void saveToPreferences(Context context, String preferenceName, String preferenceValue) {
        SharedPreferences sharedPreferences=context.getSharedPreferences(PREF_FILE_NAME, Context.MODE_PRIVATE);
        SharedPreferences.Editor editor = sharedPreferences.edit();
        editor.putString(preferenceName,preferenceValue);
        editor.apply();
    }

    public static String readFromPreferences(Context context, String preferenceName, String defaultValue) {
        SharedPreferences sharedPreferences=context.getSharedPreferences(PREF_FILE_NAME, Context.MODE_PRIVATE);
        return sharedPreferences.getString(preferenceName, defaultValue);
    }
}

我在这段代码中遇到错误:

adapter = new BalinezAdapter(getActivity(),getData());

我还包括我的适配器源代码:

 package com.balinez.wdharmana.doahindu;

import android.content.Context;
import android.support.v7.internal.view.menu.MenuView;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

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

/**
 * Created by WDHARMANA on 27/07/2015.
 */
public class BalinezAdapter extends RecyclerView.Adapter <BalinezAdapter.MyViewHolder> {

    private  LayoutInflater inflater;
    List<Information> data= Collections.emptyList();

    public BalinezAdapter(Context context) {
        inflater=LayoutInflater.from(context);
    }

    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = inflater.inflate(R.layout.custom_row, parent,false);
        MyViewHolder holder = new MyViewHolder(view);
        return holder;
    }

    @Override
    public void onBindViewHolder(MyViewHolder holder, int position) {
        Information current=data.get(position);
        holder.title.setText(current.title);
        holder.icon.setImageResource(current.iconId);
    }

    @Override
    public int getItemCount() {
        return 0;
    }

    class MyViewHolder extends RecyclerView.ViewHolder {

        TextView title;
        ImageView icon;

        public MyViewHolder(View itemView) {
            super(itemView);
            title= (TextView) itemView.findViewById(R.id.listText);
            icon= (ImageView) itemView.findViewById(R.id.listIcon);
        }
    }
}

这是information.java文件:

package com.balinez.wdharmana.doahindu;

/**
 * Created by WDHARMANA on 27/07/2015.
 */
public class Information {
    int iconId;
    String title;
}

我在一些 Stackoverflow 线程上尝试了解决方案。但这对我不起作用。如果你有同样的问题，你可以分享给我们。感谢您的提前!

Answer 1

你的适配器构造函数是

 public BalinezAdapter(Context context) {
    inflater=LayoutInflater.from(context);
}

当你有

new BalinezAdapter(getActivity(),getData());

您错过了适配器中的第二个参数。

只需更改为

  List<Information> data;
 public BalinezAdapter(Context context,List<Information> mList) {
    inflater=LayoutInflater.from(context);
    data = mList;  
}

并改变这个

@Override
public int getItemCount() {
    return 0;
}

到

@Override
public int getItemCount() {
    return data.size();
}