java - 将 xml 字符串数组中的项目添加到 fragment 内的回收器 View 中

Question

我在尝试将城市数组添加到 fragment 列表内的每个项目位置时遇到一些麻烦。我已经为我的 fragment 创建了虚拟列表模板，但在网上找不到任何有关如何将 Strings.xml 文件中数组上的值存储到回收器 View 内的值的信息。我想用数组中的城市名称替换虚拟项目(例如 1:项目 1、2:项目 2 等)。请帮忙!!!

xml 文件:

<resources>

    <string-array name="Cities">
        <item>Vancouver</item>
        <item>Kamloops</item>
        <item>Edmonton</item>
        <item>Calgary</item>
        <item>Winnipeg</item>
        <item>Toronto</item>
        <item>Montreal</item>
    </string-array>
</resources>

fragment 文件:

package com.example.fragments;

import android.content.Context;
import android.os.Bundle;

import androidx.fragment.app.Fragment;
import androidx.recyclerview.widget.GridLayoutManager;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import com.example.fragments.dummy.DummyContent;
import com.example.fragments.dummy.DummyContent.DummyItem;

import java.util.List;

/**
 * A fragment representing a list of Items.
 * <p/>
 * Activities containing this fragment MUST implement the {@link OnListFragmentInteractionListener}
 * interface.
 */
public class citiesFragment extends Fragment {

    // TODO: Customize parameter argument names
    private static final String ARG_COLUMN_COUNT = "column-count";
    // TODO: Customize parameters
    private int mColumnCount = 1;
    private OnListFragmentInteractionListener mListener;

    /**
     * Mandatory empty constructor for the fragment manager to instantiate the
     * fragment (e.g. upon screen orientation changes).
     */
    public citiesFragment() {
    }

    // TODO: Customize parameter initialization
    @SuppressWarnings("unused")
    public static citiesFragment newInstance(int columnCount) {
        citiesFragment fragment = new citiesFragment();
        Bundle args = new Bundle();
        args.putInt(ARG_COLUMN_COUNT, columnCount);
        fragment.setArguments(args);
        return fragment;
    }

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

        if (getArguments() != null) {
            mColumnCount = getArguments().getInt(ARG_COLUMN_COUNT);
        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_cities_list, container, false);

        // Set the adapter
        if (view instanceof RecyclerView) {
            Context context = view.getContext();
            RecyclerView recyclerView = (RecyclerView) view;
            if (mColumnCount <= 1) {
                recyclerView.setLayoutManager(new LinearLayoutManager(context));
            } else {
                recyclerView.setLayoutManager(new GridLayoutManager(context, mColumnCount));
            }
            recyclerView.setAdapter(new MycitiesRecyclerViewAdapter(DummyContent.ITEMS, mListener));
        }
        return view;
    }


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

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

    /**
     * This interface must be implemented by activities that contain this
     * fragment to allow an interaction in this fragment to be communicated
     * to the activity and potentially other fragments contained in that
     * activity.
     * <p/>
     * See the Android Training lesson <a href=
     * "http://developer.android.com/training/basics/fragments/communicating.html"
     * >Communicating with Other Fragments</a> for more information.
     */
    public interface OnListFragmentInteractionListener {
        // TODO: Update argument type and name
        void onListFragmentInteraction(DummyItem item);
    }
}

布局:

<androidx.recyclerview.widget.RecyclerView 
    xmlns:android="schemas.android.com/apk/res/android" 
    xmlns:app="schemas.android.com/apk/res-auto" 
    xmlns:tools="schemas.android.com/tools" 
    android:id="@+id/list" 
    android:name="com.example.fragments.citiesFragment" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:layout_marginLeft="16dp" 
    android:layout_marginRight="16dp"
    app:layoutManager="LinearLayoutManager" 
    tools:context=".citiesFragment" 
    tools:listitem="@layout/fragment_cities" />

适配器文件:

/**
 * {@link RecyclerView.Adapter} that can display a {@link DummyItem} and makes a call to the
 * specified {@link OnListFragmentInteractionListener}.
 * TODO: Replace the implementation with code for your data type.
 */
public class MycitiesRecyclerViewAdapter extends RecyclerView.Adapter<MycitiesRecyclerViewAdapter.ViewHolder> {

    private final List<DummyItem> mValues;
    private final OnListFragmentInteractionListener mListener;

    public MycitiesRecyclerViewAdapter(List<DummyItem> items, OnListFragmentInteractionListener listener) {
        mValues = items;
        mListener = listener;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.fragment_cities, parent, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(final ViewHolder holder, int position) {
        holder.mItem = mValues.get(position);
        holder.mIdView.setText(mValues.get(position).id);
        holder.mContentView.setText(mValues.get(position).content);

        holder.mView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (null != mListener) {
                    // Notify the active callbacks interface (the activity, if the
                    // fragment is attached to one) that an item has been selected.
                    mListener.onListFragmentInteraction(holder.mItem);
                }
            }
        });
    }

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

    public class ViewHolder extends RecyclerView.ViewHolder {
        public final View mView;
        public final TextView mIdView;
        public final TextView mContentView;
        public DummyItem mItem;

        public ViewHolder(View view) {
            super(view);
            mView = view;
            mIdView = (TextView) view.findViewById(R.id.item_number);
            mContentView = (TextView) view.findViewById(R.id.content);
        }

        @Override
        public String toString() {
            return super.toString() + " '" + mContentView.getText() + "'";
        }
    }
}

虚拟内容文件:

    /**

* 帮助程序类，用于为创建的用户界面提供示例内容 * Android 模板向导。 *

* TODO:在发布您的应用程序之前替换该类的所有使用。 */公共(public)类 DummyContent {

/**
 * An array of sample (dummy) items.
 */
public static final List<DummyItem> ITEMS = new ArrayList<DummyItem>();

/**
 * A map of sample (dummy) items, by ID.
 */
public static final Map<String, DummyItem> ITEM_MAP = new HashMap<String, DummyItem>();

private static final int COUNT = 25;

static {
    // Add some sample items.
    for (int i = 1; i <= COUNT; i++) {
        addItem(createDummyItem(i));
    }
}

private static void addItem(DummyItem item) {
    ITEMS.add(item);
    ITEM_MAP.put(item.id, item);
}

private static DummyItem createDummyItem(int position) {
    return new DummyItem(String.valueOf(position), "Item " + position, makeDetails(position));
}

private static String makeDetails(int position) {
    StringBuilder builder = new StringBuilder();
    builder.append("Details about Item: ").append(position);
    for (int i = 0; i < position; i++) {
        builder.append("\nMore details information here.");
    }
    return builder.toString();
}

/**
 * A dummy item representing a piece of content.
 */
public static class DummyItem {
    public final String id;
    public final String content;
    public final String details;

    public DummyItem(String id, String content, String details) {
        this.id = id;
        this.content = content;
        this.details = details;
    }

    @Override
    public String toString() {
        return content;
    }
}

}

Answer 1

您必须从资源数组 Cities 创建 DummyItem 并将其传递给您的适配器。检查以下内容:

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_cities_list, container, false);

    // Set the adapter
    if (view instanceof RecyclerView) {
        Context context = view.getContext();

        //Get cities array from resource
        String[] cities = context.getResources().getStringArray(R.array.Cities);
        List<DummyItem> mValues = new ArrayList<>();
        for(int i = 0; i < cities.length; i++) {
            mValues.add(new DummyItem(String.valueOf(i + 1), cities[i], ""));
        }

        RecyclerView recyclerView = (RecyclerView) view;
        if (mColumnCount <= 1) {
            recyclerView.setLayoutManager(new LinearLayoutManager(context));
        } else {
            recyclerView.setLayoutManager(new GridLayoutManager(context, mColumnCount));
        }

        //Pass the mValues to adapter
        recyclerView.setAdapter(new MycitiesRecyclerViewAdapter(mValues, mListener));
    }

    return view;
}