进行JSON解析时list_item无法解析或不是字段 [英] list_item cannot be resolved or is not a field while doing JSON parsing

问题描述

在通过包含某些数据的URL进行json解析时，在list_item以及id，title，url，offer和enddate上都有它.

ListAdapter adapter = new SimpleAdapter(context, jsonlist,
                    R.layout.list_item, new String[] { ID, TITLE,
                    URL, OFFER, ENDDATE }, new int[] {
                    R.id.id, R.id.title, R.id.url,
                    R.id.offer, R.id.enddate });

完整的代码是我正在做的所有主类的代码！

package com.example.googlemapandroidv2;

import java.util.ArrayList;
import java.util.List;
import com.example.googlemapandroidv2.R;
import java.util.HashMap;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.os.AsyncTask;
import android.os.Bundle;
import android.app.Activity;
import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.Intent;
import android.view.Menu;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.AdapterView.OnItemClickListener;

public class Promotions extends ListActivity {

private Context context;
private static String url = "http://expressdiner.ifeelhungry.co.uk/pushadmin/webservice/getPermotions.php";

private static final String ID = "idj";
private static final String TITLE = "titlej";
private static final String URL = "urlj";
private static final String OFFER = "offerj";
private static final String ENDDATE = "enddatej";

ArrayList<HashMap<String, String>> jsonlist = new ArrayList<HashMap<String, String>>();

ListView lv ;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    new ProgressTask(Promotions.this).execute();
}

private class ProgressTask extends AsyncTask<String, Void, Boolean> {
    private ProgressDialog dialog;

    private ListActivity activity;

    // private List<Message> messages;
    public ProgressTask(ListActivity activity) {
        this.activity = activity;
        context = activity;
        dialog = new ProgressDialog(context);
    }

    private Context context;

    protected void onPreExecute() {
        this.dialog.setMessage("Progress start");
        this.dialog.show();
    }

    @Override
    protected void onPostExecute(final Boolean success) {
        if (dialog.isShowing()) {
            dialog.dismiss();
        }
        ListAdapter adapter = new SimpleAdapter(context, jsonlist,
                R.layout.list_item, new String[] { ID, TITLE,
                        URL, OFFER, ENDDATE }, new int[] {
                        R.id.id, R.id.title, R.id.url,
                        R.id.offer, R.id.enddate });

        setListAdapter(adapter);

        // select single ListView item
         lv = getListView();
    }

    protected Boolean doInBackground(final String... args) {

        JSONParser jParser = new JSONParser();

        // get JSON data from URL
        JSONArray json = jParser.getJSONFromUrl(url);

        for (int i = 0; i < json.length(); i++) {

            try {
                JSONObject c = json.getJSONObject(i);
                String idj = c.getString(ID);

                String titlej = c.getString(TITLE);
                String urlj = c.getString(URL);
                String offerj = c.getString(OFFER);
                String enddatej =c.getString(ENDDATE);
                HashMap<String, String> map = new HashMap<String, String>();

                // Add child node to HashMap key & value
                map.put(ID, idj);
                map.put(TITLE, titlej);
                map.put(URL, urlj);
                map.put(OFFER, offerj);
                map.put(ENDDATE, enddatej);
                jsonlist.add(map);
            }
            catch (JSONException e) {
                e.printStackTrace();
            }
        }
        return null;
    }
}
}

XML代码为

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.googlemapandroidv2.Promotions" >

<ListView
    android:id="@android:id/list"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"/>

</LinearLayout>

推荐答案

list_item在执行JSON时无法解析或不是字段 解析

list_item cannot be resolved or is not a field while doing JSON parsing

可能您没有在res/layout/中使用list_item名称创建布局.

Probably you have not created layout in res/layout/ with list_item name.

使用list_item.xml

在其中做什么?

what to do in it ?

SimpleAdapter接受我们要在ListView行中显示的布局的第三个参数id

SimpleAdapter takes third params id of layout which we want to show in ListView row

您要将R.id.id, R.id.title, R.id.url,R.id.offer,R.id.enddate id传递给适配器以映射Map中的数据，因此在list_item.xml中添加所有TextView，其中您要显示与最后一个参数传递给适配器的id相同的值

You are passing R.id.id, R.id.title, R.id.url,R.id.offer,R.id.enddate id's to adapter to map data from Map so Add all TextViews in list_item.xml in which you want to show values with same id's which you are passing as last parameter to adapter

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