[英]How to parse this Json Array in android
我有一個想在我的Android應用程序中解析的jsonArray。
數組:-
[
{
"id": 96905,
"category": "topup",
"detail": "Full talktime of Rs.55 + 1 local airtel SMS free for 1 day",
"price": 55,
"keywords": "topup",
"updated": "2016-01-07 00:16:23.0",
"validity": "7 days",
"service": "Airtel",
"sourceUri": "https://pay.airtel.com/online-payments/recharge.jsp",
"circle": "Assam",
"talktime": 55
},
{
"id": 90397,
"category": "topup",
"price": 510,
"keywords": "topup",
"updated": "2016-01-07 00:16:23.0",
"service": "Airtel",
"sourceUri": "https://pay.airtel.com/online-payments/recharge.jsp",
"circle": "Assam",
"talktime": 520
},
{
"id": 90399,
"category": "topup",
"price": 1000,
"keywords": "topup",
"updated": "2016-01-07 00:16:23.0",
"service": "Airtel",
"sourceUri": "https://pay.airtel.com/online-payments/recharge.jsp",
"circle": "Assam",
"talktime": 1020
}]
我的Android代碼:-
的AsyncTask: -
private class DownloadJSON extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
mProgressDialog = new ProgressDialog(MainActivity.this);
mProgressDialog.setTitle("Android JSON Parse Tutorial");
mProgressDialog.setMessage("Loading...");
mProgressDialog.setIndeterminate(false);
mProgressDialog.show();
}
@Override
protected Void doInBackground(Void... params) {
// Create an array
arraylist = new ArrayList<HashMap<String, String>>();
try {
JSONObject jo;
JSONArray ja2 = JSONfunctions.getJSONfromURL("http://app.ireff.in:9090/IreffWeb/android?service=airtel&circle=assam");
for (int i = 0; i < ja2.length(); i++) {
HashMap<String, String> map = new HashMap<String, String>();
jo = ja2.getJSONObject(i);
map.put("rank", jo.getString("price"));
map.put("country", jo.getString("validity"));
map.put("population", jo.getString("talktime"));
arraylist.add(map);
}
} catch (JSONException e) {
Log.e("Error", e.getMessage());
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(Void args) {
listview = (ListView) findViewById(R.id.listview);
adapter = new ListViewAdapter(MainActivity.this, arraylist);
listview.setAdapter(adapter);
mProgressDialog.dismiss();
}
}
JsonFunctions.java
public class JSONfunctions {
public static JSONArray getJSONfromURL(String url) {
InputStream is = null;
String result = "";
JSONArray jArray = null;
// Download JSON data from URL
try {
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(url);
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
} catch (Exception e) {
Log.e("log_tag", "Error in http connection " + e.toString());
}
// Convert response to string
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
result = sb.toString();
} catch (Exception e) {
Log.e("log_tag", "Error converting result " + e.toString());
}
try {
jArray = new JSONArray(result);
} catch (JSONException e) {
Log.e("log_tag", "Error parsing data " + e.toString());
}
return jArray;
}
}
我得到的錯誤:-
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'int org.json.JSONArray.length()' on a null object reference
at com.androidbegin.jsonparsetutorial.MainActivity$DownloadJSON.doInBackground(MainActivity.java:67)
at com.androidbegin.jsonparsetutorial.MainActivity$DownloadJSON.doInBackground(MainActivity.java:39)
at android.os.AsyncTask$2.call(AsyncTask.java:292)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
at java.lang.Thread.run(Thread.java:818)
json托管在這里
我正在按照本教程學習json解析,但是本教程使用jsonObject,但是我無法解析json數組。
不是重復的內容:- 發送和解析JSON對象,或者如何在android中解析此JSON數組?
讓我提供另一種解決方案。 現有代碼的簡單得多的版本是:
更新的代碼:
private class DownloadJSON extends AsyncTask<Void, Void, Void> {
ProgressDialog mProgressDialog;
ArrayList<HashMap<String, String>> arraylist = new ArrayList<>();
@Override
protected void onPreExecute() {
super.onPreExecute();
mProgressDialog = new ProgressDialog(TestListActivity.this);
mProgressDialog.setTitle("Android JSON Parse Tutorial");
mProgressDialog.setMessage("Loading...");
mProgressDialog.setIndeterminate(false);
mProgressDialog.show();
}
@Override
protected Void doInBackground(Void... params) {
String url = "http://app.ireff.in:9090/IreffWeb/android?service=airtel&circle=assam";
OkHttpClient okHttpClient = new OkHttpClient();
okHttpClient.setConnectTimeout(30, TimeUnit.SECONDS);
okHttpClient.setReadTimeout(30, TimeUnit.SECONDS);
okHttpClient.setRetryOnConnectionFailure(true);
Request request = new Request.Builder()
.url(url)
.build();
Call call = okHttpClient.newCall(request);
try {
Response response = call.execute();
String strResult = response.body().string();
JSONArray JARoot = new JSONArray(strResult);
for (int i = 0; i < JARoot.length(); i++) {
JSONObject JORoot = JARoot.getJSONObject(i);
HashMap<String, String> map = new HashMap<>();
if (JORoot.has("category") && JORoot.getString("category").equals("topup")) {
if (JORoot.has("id")) {
map.put("id", JORoot.getString("id"));
}
if (JORoot.has("category")) {
map.put("category", JORoot.getString("category"));
}
if (JORoot.has("detail")) {
map.put("detail", JORoot.getString("detail"));
} else {
map.put("detail", null);
}
if (JORoot.has("price")) {
map.put("price", JORoot.getString("price"));
}
/** ADD THE COLLECTED DATA TO THE ARRAY LIST **/
arraylist.add(map); /* THE DATA WILL ONLY BE ADDED IF THE CATEGORY = "topup" */
}
}
} catch (IOException | JSONException e) {
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(Void aVoid) {
super.onPostExecute(aVoid);
ListView testList = (ListView) findViewById(R.id.testList);
TestListAdapter adapter = new TestListAdapter(TestListActivity.this, arraylist);
testList.setAdapter(adapter);
mProgressDialog.dismiss();
}
}
private class TestListAdapter extends BaseAdapter {
Activity activity;
// LAYOUTINFLATER TO USE A CUSTOM LAYOUT
LayoutInflater inflater = null;
// ARRAYLIST TO GET DATA FROM THE ACTIVITY
ArrayList<HashMap<String, String>> arrItem;
public TestListAdapter(Activity activity, ArrayList<HashMap<String, String>> arrItem) {
this.activity = activity;
// CAST THE CONTENTS OF THE ARRAYLIST IN THE METHOD TO THE LOCAL INSTANCE
this.arrItem = arrItem;
// INSTANTIATE THE LAYOUTINFLATER
inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
@Override
public int getCount() {
return arrItem.size();
}
@Override
public Object getItem(int position) {
return arrItem.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public void notifyDataSetChanged() {
super.notifyDataSetChanged();
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
// A VIEWHOLDER INSTANCE
ViewHolder holder;
// CAST THE CONVERTVIEW IN A VIEW INSTANCE
View vi = convertView;
// CHECK CONVERTVIEW STATUS
if (convertView == null) {
// CAST THE CONVERTVIEW INTO THE VIEW INSTANCE vi
vi = inflater.inflate(R.layout.test_item, null);
// INSTANTIATE THE VIEWHOLDER INSTANCE
holder = new ViewHolder();
/***** CAST THE LAYOUT ELEMENTS *****/
/* TOP (PRIMARY) ELEMENTS */
holder.txtPrice = (TextView) vi.findViewById(R.id.txtPrice);
holder.txtDetail = (TextView) vi.findViewById(R.id.txtDetail);
// SET THE TAG TO "vi"
vi.setTag(holder);
} else {
// CAST THE VIEWHOLDER INSTANCE
holder = (ViewHolder) vi.getTag();
}
if (arrItem.get(position).get("price") != null) {
String strPrice = arrItem.get(position).get("price");
holder.txtPrice.setText("PRICE: " + strPrice);
}
if (arrItem.get(position).get("detail") != null) {
String strDetail = arrItem.get(position).get("detail");
holder.txtDetail.setText("DETAIL: " + strDetail);
} else {
holder.txtDetail.setText("DETAIL: NA");
}
return vi;
}
private class ViewHolder {
/* TOP (PRIMARY) ELEMENTS */
TextView txtPrice;
TextView txtDetail;
}
}
為了完整起見,我還包括了adapter
的代碼。 這是一個簡單的實現。 根據您的要求進行清理/優化/自定義。
compile
語句添加到模塊的gradle文件的dependencies部分中: compile 'com.squareup.okhttp:okhttp:2.5.0'
。 檢查鏈接以獲取更新的版本。 if
語句,考慮到並非每個記錄都具有相同的節點集。 jsonResponse="";
for(int i = 0; i<response.length(); i++) {
JSONObject person = (JSONObject) response.get(i);
String id = person.getString("id");
String category = person.getString("category");
}
您的BufferReader
無法在您的類JSONfunctions中按預期方式工作,請在您的類中進行一些更改,它看起來應該像
JSONfunctions.java
public class JSONfunctions {
public static JSONArray getJSONfromURL(String url) {
InputStream is = null;
String result = "";
JSONArray jArray = null;
// Download JSON data from URL
try {
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(url);
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
} catch (Exception e) {
Log.e("log_tag", "Error in http connection " + e.toString());
}
StringBuffer sb = new StringBuffer("");
try {
URL urls = new URL(url);
URLConnection urlConnection;
urlConnection = urls.openConnection();
InputStream in = urlConnection.getInputStream();
BufferedReader br=new BufferedReader(new InputStreamReader(in));
String line = "";
while ((line = br.readLine()) != null) {
sb.append(line);
}
System.out.println(sb);
result=sb.toString();
} catch (IOException e) {}
catch (Exception e) {}
try {
jArray = new JSONArray(result);
} catch (JSONException e) {
Log.e("log_tag", "Error parsing data " + e.toString());
}
return jArray;
}
}
並避免異常檢查是否JSONArray
不為空則只有它去跑for
這樣的循環:
JSONArray ja2 = JSONfunctions.getJSONfromURL("http://app.ireff.in:9090/IreffWeb/android? service=airtel&circle=assam");
if(ja2!=null)
for (int i = 0; i < ja2.length(); i++) {}
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