[英]How to parse the json data and display it in Listview in Flutter?
[英]parse the json data and display in listview
我已经从json解析了一个数据,然后将其添加到ArrayList中。 现在,我必须在列表视图中显示它。 怎么做? 在执行doInBackground()时发生错误。 我如何设置适配器以查看此内容。 我很混乱。 提出好的解决方案
<ListView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@android:id/list">
</ListView>
public class MainActivity extends ListActivity {
String url="https://maps.googleapis.com/maps/api/place/nearbysearch/json?location=11.021459,76.916332&radius=2000&types=atm&sensor=false&key=AIzaSyD7c1IID7zDCdcfpC69fC7CUqLjz50mcls";
ArrayList<HashMap<String, String>> cList;
ArrayAdapter<String> adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
new googleplaces().execute();
}
private class googleplaces extends AsyncTask<Void, Void, Void> {
@Override
protected Void doInBackground(Void... arg0) {
ServiceHandler sh = new ServiceHandler();
// Making a request to url and getting response
String jsonStr = sh.makeServiceCall(url, ServiceHandler.GET);
HashMap<String, String> parse = new HashMap<>();
Log.d("Response: ", "> " + jsonStr);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
JSONArray jsonArray = jsonObj.getJSONArray("results");
for (int i=0;i<jsonArray.length();i++) {
JSONObject object = jsonArray.getJSONObject(i);
String name = object.optString("name").toString();
if (object.has("opening_hours")) {
if (object.has("open_now")) {
if (jsonArray.getJSONObject(i).getJSONObject("opening_hours").getString("open_now").equals("true")) {
//
} else {
//
}
}
} else {
//
}
JSONArray typesarray = object.getJSONArray("types");
for (i = 0; i < typesarray.length(); i++) {
String type = typesarray.getString(i);
String vicinity = object.optString("vicinity").toString();
Log.d("test",vicinity);
parse.put("name", name);
parse.put("type", type);
parse.put("vicinity", vicinity);
cList.add(parse);
}
}
} catch (JSONException e) {
e.printStackTrace();
}
} else {
Log.e("ServiceHandler", "Couldn't get any data from the url");
}
return null;
}
protected void onPostExecute(Void result) {
super.onPostExecute(result);
}
}
}
1.制作一个空但不为空的ArrayList
2.将ArrayList传递给适配器
3.将适配器设置为您的ListView
4.下载数据,将它们放入ArrayList
5. 调用adapter.notifyDataSetChange()
然后ListView将刷新。
使用下面的代码来解析您的json数据,然后在onPostExecute()中设置适配器:
private class googleplaces extends AsyncTask<Void, Void, List<Result>> {
@Override
protected List<Result> doInBackground(Void... arg0) {
//Create list to save list of result objects
List<Result> list = new ArrayList<>();
StringBuffer mBuffer = new StringBuffer();
HttpClient client = new DefaultHttpClient();
HttpGet get = new HttpGet(url);
try {
HttpResponse response = client.execute(get);
InputStream inputStream = response.getEntity().getContent();
BufferedReader br = new BufferedReader(new InputStreamReader(inputStream));
String line = "";
while ((line = br.readLine()) != null) {
mBuffer.append(line);
}
Log.d("Response: ", "> " + mBuffer.toString());
} catch (IOException e) {
e.printStackTrace();
}
String jsonResult = mBuffer.toString();
if (jsonResult != null) {
try {
JSONObject jsonObj = new JSONObject(jsonResult);
JSONArray jsonArray = jsonObj.getJSONArray("results");
for (int i = 0; i < jsonArray.length(); i++) {
//Creating Result model class object to store details
Result result = new Result();
JSONObject object = jsonArray.getJSONObject(i);
String name = object.optString("name").toString();
if (object.has("id")) {
result.setId(object.getString("id"));
} else {
result.setId("");
}
if (object.has("name")) {
result.setName(object.getString("name"));
} else {
result.setName("");
}
if (object.has("vicinity")) {
result.setName(object.getString("vicinity"));
} else {
result.setVicinity("");
}
if (object.has("opening_hours")) {
if (object.getJSONObject("opening_hours").has("open_now")) {
result.setOpening_now(object.getJSONObject("opening_hours").getString("open_now"));
} else {
result.setOpening_now("");
}
}
list.add(result);
}
for (int i = 0; i < list.size(); i++) {
CustomLog.d("List = " + list.get(i));
}
} catch (JSONException e) {
e.printStackTrace();
}
} else {
Log.e("ServiceHandler", "Couldn't get any data from the url");
}
return list;
}
protected void onPostExecute(List<Result> result) {
super.onPostExecute(result);
//Here update result on UI
}
}
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