我有一个代码，我应该传递一个静态用户ID进行身份验证，然后从URL获取JSON响应并将其显示在listview中。但是我得到一个错误，指出“ JSON解析错误：（JSON数组）中没有值”。请帮助
MainActivity.java：
public class MainActivity extends AppCompatActivity {
private String TAG = MainActivity.class.getSimpleName();
private ProgressDialog pDialog;
private ListView lv;
// URL to get contacts JSON
private static String url = "url";
ArrayList<HashMap<String, String>> contactList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
contactList = new ArrayList<>();
lv = (ListView) findViewById(R.id.list);
new GetContacts().execute();
}
/**
* Async task class to get json by making HTTP call
*/
private class GetContacts extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
// Showing progress dialog
pDialog = new ProgressDialog(MainActivity.this);
pDialog.setMessage("Please wait...");
pDialog.setCancelable(false);
pDialog.show();
}
@Override
protected Void doInBackground(Void... arg0) {
List<NameValuePair> list=new ArrayList<>();
list.add(new BasicNameValuePair("user_id", "2"));
HttpHandler sh = new HttpHandler();
// Making a request to url and getting response
String jsonStr = sh.makeServiceCall(url);
Log.e(TAG, "Response from url: " + jsonStr);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
// Getting JSON Array node
JSONArray contacts = jsonObj.getJSONArray("promotion_lists");
// looping through All Contacts
for (int i = 0; i < contacts.length(); i++) {
JSONObject c = contacts.getJSONObject(i);
String promotion_id = c.getString("promotion_id");
String promotion_title = c.getString("promotion_title");
String promotion_description = c.getString("promotion_description");
//
HashMap<String, String> contact = new HashMap<>();
// adding each child node to HashMap key => value
contact.put("promotion_id", promotion_id);
contact.put("promotion_title", promotion_title);
contact.put("promotion_description", promotion_description);
// adding contact to contact list
contactList.add(contact);
}
} catch (final JSONException e) {
Log.e(TAG, "Json parsing error: " + e.getMessage());
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(),
"Json parsing error: " + e.getMessage(),
Toast.LENGTH_LONG)
.show();
}
});
}
} else {
Log.e(TAG, "Couldn't get json from server.");
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(),
"Couldn't get json from server. Check LogCat for possible errors!",
Toast.LENGTH_LONG)
.show();
}
});
}
return null;
}
@Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
Log.e("SignUpRsp", String.valueOf(result));
// Dismiss the progress dialog
if (pDialog.isShowing())
pDialog.dismiss();
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
MainActivity.this, contactList,
R.layout.list_item, new String[]{"promotion_id", "promotion_title",
"promotion_description"}, new int[]{R.id.promotion_id,
R.id.promotion_title, R.id.promotion_desc});
lv.setAdapter(adapter);
}
}
public String PostData(String[] valuse) {
String s="";
try
{
HttpClient httpClient=new DefaultHttpClient();
HttpPost httpPost=new HttpPost("url");
List<NameValuePair> list=new ArrayList<>();
list.add(new BasicNameValuePair("user_id", "value"));
httpPost.setEntity(new UrlEncodedFormEntity(list));
HttpResponse httpResponse= httpClient.execute(httpPost);
HttpEntity httpEntity=httpResponse.getEntity();
s= readResponse(httpResponse);
}
catch(Exception exception) {}
return s;
}
public String readResponse(HttpResponse res) {
InputStream is=null;
String return_text="";
try {
is=res.getEntity().getContent();
BufferedReader bufferedReader=new BufferedReader(new InputStreamReader(is));
String line="";
StringBuffer sb=new StringBuffer();
while ((line=bufferedReader.readLine())!=null)
{
sb.append(line);
}
return_text=sb.toString();
} catch (Exception e)
{
}
return return_text;
}
}
JSON响应：
{
"status": "1",
"message": "Ok",
"promotion_lists": [
{
"promotion_id": "3",
"promotion_image_name": "1.jpg",
"promotion_image_url": "url.jpg",
"promotion_title": "winner",
"promotion_description": "good\ngold\nred",
"admin_status": "1",
"promotion_status": "1",
"promotion_status_description": "Live"
},
]
}
答案 0 :(得分：1)
您的json也有问题，您可以尝试使用此输出json吗？不需要数组中的最后一个逗号。
{
"status": "1",
"message": "Ok",
"promotion_lists": [
{
"promotion_id": "3",
"promotion_image_name": "1.jpg",
"promotion_image_url": "url.jpg",
"promotion_title": "winner",
"promotion_description": "good\ngold\nred",
"admin_status": "1",
"promotion_status": "1",
"promotion_status_description": "Live"
}
]
}
答案 1 :(得分：1)
您的JSON解析正确
如果您的响应状态响应代码为1，则需要解析JSON
示例代码
尝试一下
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
// check here of your status of response
// is status is 0 USER NOT FOUND
if(jsonObj.getString("status").equals("0")){
MainActivity.this.runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(MainActivity.this, jsonObj.getString("message"), Toast.LENGTH_SHORT).show();
}
});
// is status is 1 PARSE YOUR JSON
}else {
JSONArray contacts = jsonObj.getJSONArray("promotion_lists");
// looping through All Contacts
for (int i = 0; i < contacts.length(); i++) {
JSONObject c = contacts.getJSONObject(i);
String promotion_id = c.getString("promotion_id");
String promotion_title = c.getString("promotion_title");
String promotion_description = c.getString("promotion_description");
HashMap<String, String> contact = new HashMap<>();
// adding each child node to HashMap key => value
contact.put("promotion_id", promotion_id);
contact.put("promotion_title", promotion_title);
contact.put("promotion_description", promotion_description);
// adding contact to contact list
contactList.add(contact);
}
}
} catch (final JSONException e) {
Log.e(TAG, "Json parsing error: " + e.getMessage());
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(),
"Json parsing error: " + e.getMessage(),
Toast.LENGTH_LONG)
.show();
}
});
}
}
答案 2 :(得分：1)
您可以使用此解决方案
public class GetContacts extends AsyncTask<String, Void, String> {
protected void onPreExecute() {
pDialog = new ProgressDialog(MainActivity.this);
pDialog.setMessage("Please wait...");
pDialog.setCancelable(false);
pDialog.show();
}
protected String doInBackground(String... arg0) {
try {
URL url = new URL(URL HERE);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("POST");
conn.setRequestProperty("Content-Type", "application/json;charset=UTF-8");
conn.setRequestProperty("Accept", "application/json");
conn.setDoOutput(true);
conn.setDoInput(true);
conn.setReadTimeout(5000);
conn.setConnectTimeout(5000);
JSONObject postDataParams = new JSONObject();
postDataParams.put("user_id", user_id);
Log.i("JSON", postDataParams.toString());
DataOutputStream os = new DataOutputStream(conn.getOutputStream());
//os.writeBytes(URLEncoder.encode(jsonParam.toString(), "UTF-8"));
os.writeBytes(postDataParams.toString());
os.flush();
os.close();
Log.i("STATUS", String.valueOf(conn.getResponseCode()));
Log.i("MSG", conn.getResponseMessage());
int responseCode = conn.getResponseCode();
if (responseCode == HttpsURLConnection.HTTP_OK) {
BufferedReader in = new BufferedReader(new
InputStreamReader(
conn.getInputStream()));
StringBuffer sb = new StringBuffer("");
String line = "";
while ((line = in.readLine()) != null) {
sb.append(line);
break;
}
in.close();
conn.disconnect();
return sb.toString();
} else {
conn.disconnect();
return new String("false : " + responseCode);
}
} catch (Exception e) {
return new String("Exception: " + e.getMessage());
}
}
@Override
protected void onPostExecute(String jsonStr) {
try {
pDialog();
Log.e(TAG, "Response from url: " + jsonStr);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
// Getting JSON Array node
JSONArray contacts = jsonObj.getJSONArray("promotion_lists");
// looping through All Contacts
for (int i = 0; i < contacts.length(); i++) {
JSONObject c = contacts.getJSONObject(i);
String promotion_id = c.getString("promotion_id");
String promotion_title = c.getString("promotion_title");
String promotion_description = c.getString("promotion_description");
//
HashMap<String, String> contact = new HashMap<>();
// adding each child node to HashMap key => value
contact.put("promotion_id", promotion_id);
contact.put("promotion_title", promotion_title);
contact.put("promotion_description", promotion_description);
// adding contact to contact list
contactList.add(contact);
}
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
MainActivity.this, contactList,
R.layout.list_item, new String[]{"promotion_id", "promotion_title",
"promotion_description"}, new int[]{R.id.promotion_id,
R.id.promotion_title, R.id.promotion_desc});
lv.setAdapter(adapter);
} catch (final JSONException e) {
Log.e(TAG, "Json parsing error: " + e.getMessage());
Toast.makeText(getApplicationContext(),
"Json parsing error: " + e.getMessage(),
Toast.LENGTH_LONG)
.show();
}
} else {
Log.e(TAG, "Couldn't get json from server.");
Toast.makeText(getApplicationContext(),
"Json parsing error: " + e.getMessage(),
Toast.LENGTH_LONG)
.show();
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
您不需要在 Asynctask 中使用 runOnUiThread 的另一件事，因为 两者都是 helper线程，它们用于更新UI，您不必 在其中使用 runOnUIThread ，只是简单地显示吐司，而不使用它 将显示它，阅读文档 https://developer.android.com/guide/components/processes-and-threads
答案 3 :(得分：1)
JSONArray引发错误，因为promotion_lists带有项目，但逗号不必要。
{
"status": "1",
"message": "Ok",
"promotion_lists": [
{
"promotion_id": "3",
"promotion_image_name": "1.jpg",
"promotion_image_url": "url.jpg",
"promotion_title": "winner",
"promotion_description": "good\ngold\nred",
"admin_status": "1",
"promotion_status": "1",
"promotion_status_description": "Live"
}
]
}
答案 4 :(得分：1)
您的JSON解析看起来不错。问题出在您的JSON响应上。这不是有效的JSON响应，因为JSON数组“ promotion_lists”之后有不必要的逗号。尝试删除逗号。