java - 无法转换为 JSONArray 以在 ListView 中显示

Question

我正在尝试将 json 数组从互联网转换为 ListView 。服务器中的 php 代码正常工作并返回下面的 json 字符串。 logcat 中的结果 json 是:

11-09 20:47:04.170: I/AllNotes >> jSon >>(429): {"notes":{"3":{"note_subject":"dshjdsfjsdfsdhf","note_id":"4","note_date":"0000-00-00"},"2":{"note_subject":"dshjdsfjsdfsdhf","note_id":"3","note_date":"0000-00-00"},"1":{"note_subject":"dshjdsfjsdfsdhf","note_id":"2","note_date":"0000-00-00"},"0":{"note_subject":"dshjdsfjsdfsdhf","note_id":"1","note_date":"0000-00-00"},"7":{"note_subject":"dshjdsfjsdfsdhf","note_id":"8","note_date":"1391\/8\/19"},"6":{"note_subject":"dshjdsfjsdfsdhf","note_id":"7","note_date":""},"5":{"note_subject":"dshjdsfjsdfsdhf","note_id":"6","note_date":""},"4":{"note_subject":"dshjdsfjsdfsdhf","note_id":"5","note_date":""}},
"success":"1"}

我的 JSONParser 类是:

package ir.mohammadi.android.nightly;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.util.List;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONException;
import org.json.JSONObject;

import android.util.Log;

public class JSONParser {
    static InputStream is = null;
    static JSONObject jObj = null;
    static String json = null;

    public JSONParser() {

    }

    public JSONObject getJSONFromUrl(String url, List<NameValuePair> params) {

        // Make HTTP connection
        try {

            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(url);
            httpPost.setEntity(new UrlEncodedFormEntity(params));

            HttpResponse httpResponse = httpClient.execute(httpPost);
            HttpEntity httpEntity = httpResponse.getEntity();
            is = httpEntity.getContent();

            Log.i("Input stream >> ", is.toString());

        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        try {

            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    is, "UTF-8"), 8);
            StringBuilder sb = new StringBuilder();
            String line = null;
            while ((line = reader.readLine()) != null) {
                sb.append(line + "\n");
            }
            is.close();
            json = sb.toString();

            Log.i("JSON string builder >> ", json.toString());
        } catch (Exception e) {
            Log.e("Buffer Error", "Error converting result " + e.toString());
        }

        try {
            jObj = new JSONObject(json.substring(1, json.length()));
        } catch (JSONException e) {
            Log.e("JSON Parser", "Error parsing data " + e.toString());
        }
        return jObj;
    }
}

错误是:org.json.JSONObject 类型的注释无法转换为 JSONArray

在 ListView 中显示 json 的代码是:

package ir.mohammadi.android.nightly;

import java.util.ArrayList;
import java.util.HashMap;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
import android.widget.Toast;

public class AllNotes extends ListActivity {

    ProgressDialog pDialog;

    ArrayList<HashMap<String, String>> noteList;

    JSONArray notes = null;

    JSONObject jSon = null;

    private static String KEY_SUCCESS = "success";
    private static String KEY_ERROR_MSG = "error_message";
    private static String KEY_NOTE_ID = "note_id";
    private static String KEY_NOTE_SUBJECT = "note_subject";
    private static String KEY_NOTE_DATE = "note_date";

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.note_list);

        noteList = new ArrayList<HashMap<String, String>>();
        new LoadAllNotes().execute();
        ListView lv = getListView();

        lv.setOnItemClickListener(new OnItemClickListener() {
            public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id) {

                String note_id = ((TextView) view
                        .findViewById(R.id.list_lbl_id)).getText().toString();
                Intent i = new Intent(getApplicationContext(), NoteDetail.class);
                i.putExtra("note_id", note_id);
                startActivityForResult(i, 100);
            }
        });
    }

    public class LoadAllNotes extends AsyncTask<String, String, String> {
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pDialog = new ProgressDialog(AllNotes.this);
            pDialog.setMessage("لطفا صبر کنید...");
            pDialog.setIndeterminate(false);
            pDialog.setCancelable(true);
            pDialog.show();
        }

        protected String doInBackground(String... args) {

            UserFunctions userFunctions = new UserFunctions();

            jSon = userFunctions.getAllNotes("12");

            Log.i("AllNotes >> jSon >>", jSon.toString());

            return null;
        }

        protected void onPostExecute(String file_url) {
            pDialog.dismiss();
            try {
                if (jSon.has(KEY_SUCCESS)) {
                    String success = jSon.getString(KEY_SUCCESS);
                    if (success.equals("1")) {
                        notes = jSon.getJSONArray("notes");
                        for (int i = 0; i < notes.length(); i++) {
                            JSONObject c = notes.getJSONObject(i);

                            String id = c.getString(KEY_NOTE_ID);
                            String subject = c.getString(KEY_NOTE_SUBJECT);
                            String date = c.getString(KEY_NOTE_DATE);

                            HashMap<String, String> map = new HashMap<String, String>();
                            map.put(KEY_NOTE_ID, id);
                            map.put(KEY_NOTE_SUBJECT, subject);
                            map.put(KEY_NOTE_DATE, date);

                            noteList.add(map);
                        }

                    }
                } else {

                    finish();
                    Toast.makeText(getApplicationContext(),
                            jSon.getString(KEY_ERROR_MSG), Toast.LENGTH_SHORT)
                            .show();

                    Log.i("AllNotes >> No nightly >>", "...");

                    Intent i = new Intent(getApplicationContext(), login.class);
                    i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                    startActivity(i);
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }

            runOnUiThread(new Runnable() {

                public void run() {
                    ListAdapter adapter = new SimpleAdapter(AllNotes.this,
                            noteList, R.layout.list_item, new String[] {
                                    KEY_NOTE_ID, KEY_NOTE_SUBJECT,
                                    KEY_NOTE_DATE }, new int[] {
                                    R.id.list_lbl_id, R.id.list_lbl_subject,
                                    R.id.list_lbl_date });
                    setListAdapter(adapter);
                }
            });
        }
    }
}

PHP代码是:

public function getNotesList($user_id)
    {
        $result = mysql_query("SELECT `id`, `note_subject`, `note_date` FROM `tbl_notes` WHERE `user_id` = '$user_id'");

        if (mysql_num_rows($result) > 0) {

            $response = array();
            $response["success"] = "1";

            $response["notes"] = array();

            while ($row = mysql_fetch_array($result)) {
                $note = array();
                $note["note_id"] = $row["id"];
                $note["note_subject"] = $row["note_subject"];
                $note["note_date"] = $row["note_date"];

                array_push($response["notes"], $note);
            }
            return $response;
        }
    }

和

if ($tag == 'getNotesList') {

                            $user_id = $_POST['user_id'];
                            $result = $db->getNotesList($user_id);

                            if ($result) {
                                error_log("Index getNotesList Json >>" . json_encode($result) . "\r\n", 3,
                                    "Log.log");
                                echo json_encode($result, JSON_FORCE_OBJECT);
                            } else {
                                $response["error"] = "1";
                                $response["error_message"] = "no row";
                                echo json_encode($response, JSON_FORCE_OBJECT);
                            }
                        }

我该如何解决这个问题？谢谢。

Answer 1

使用

  JSONObject notes = jSon.getJSONObject("notes");

而不是

JSONArray notes = jSon.getJSONArray("notes");`

因为您的 json 字符串是 JsonOject 的集合，所以它不包含任何 JsonArray。

在解析 Json 字符串的结构之前，您可以使用以下 json 检查器站点

http://jsonviewer.stack.hu/