问题描述
我需要使用从 JSONArray 获得的值绘制地图标记。我使用了以下代码。当我直接传递纬度和经度值时它工作正常,但是当我传递从 JSONArray 获取的值时,地图没有被绘制。
StringRequest stringRequest = new StringRequest(Request.Method.POST,url,new Response.Listener<String>() {
@Override
public void onResponse(String response) {
try {
//converting the string to json array object
JSONObject object = new JSONObject(response);
if (object.getInt("status") == 200) {
JSONArray jsonArray = object.getJSONArray("data");
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject pobj = jsonArray.getJSONObject(i);
lat = Double.parseDouble(pobj.getString("latitude"));
lon = Double.parseDouble(pobj.getString("longitude")); pobj.getDouble("latitude")+","+pobj.getDouble("longitude");
Log.i("MAP",""+response);
Log.i("lat-",""+lat);
Log.i("lon-",""+lon);
}
}
} catch (JSONException e) {
e.printstacktrace();
}
}
private void displayTrack() {
Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setData(Uri.parse("geo:" + lat + "," + lon + "?q=" + lat + "," + lon + ")")); //NOT WORKING
intent.setData(Uri.parse("geo:" + 15.824730932928347 + "," + 74.50431285009074 + "?q=" + 15.824730932928347 + "," + 74.50431285009074 + ")")); //WORKING
startActivity(intent);
}
以下是我的数据:
"data": [
{
"id": "43","site_no": "361","p_id_no": "68-1-361","sas_application_no": "95534","latitude": "15.824730932928347","longitude": "74.50431285009074",
解决方法
来自评论:使用此逻辑,您将分配 lat
中最后一个对象的 lon
& jsonArray
。最有可能的是,当您到达最后一个对象时,您的一个对象已经导致了一些 JSONException
或者您的最后一个元素具有空值或 null 值。在任何情况下,它都被分配了空值。请全面检查您的 JSON 响应。
所以我创建了一个小演示,你可以怎么做。阅读内嵌注释以了解:
public class MainActivity extends AppCompatActivity {
//declare the global variable,initially they are null
private Double lat,lon;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// prepare request
StringRequest stringRequest = new StringRequest(Request.Method.POST,"url",new Response.Listener<String>() {
@Override
public void onResponse(String response) {
try {
//converting the string to json array object
JSONObject object = new JSONObject(response);
//check
if (object.getInt("status") == 200) {
JSONArray jsonArray = object.getJSONArray("data");
for (int i = 0; i < jsonArray.length(); i++) {
//keep getting the new objects
JSONObject pobj = jsonArray.getJSONObject(i);
//assign the last object lat/lon
lat = Double.parseDouble(pobj.getString("latitude"));
lon = Double.parseDouble(pobj.getString("longitude"));
}
//if they are not null then call the activity
if (lat != null && lon != null) {
DisplayTrack(lat,lon);
}
}
} catch (JSONException e) {
e.printStackTrace();
}
}
},new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
});
// call your request like you do
}
//declared the function out of the Network call scope
private void DisplayTrack(Double lat,Double lon) {
Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setData(Uri.parse("geo:" + lat + "," + lon + "?q=" + lat + "," + lon + ")")); //NOT WORKING
startActivity(intent);
}
}