Add a first value to spinner when spinner data is came from server

Add String -Select Your Choice- as the first element in the array List.

 String choice1 =  "-Select Your Choice-";
 allNames.add(choice1);     
 JSONArray array = jsonObject.getJSONArray("Spinner value");
                for (int i = 0; i < array.length(); i++) {
                    JSONObject job = array.getJSONObject(i);
                    String name = job.getString("spinner_data");
                    allNames.add(name);

                }

                ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>
                        (MainActivity.this, android.R.layout.simple_spinner_item, allNames);


                spinner.setAdapter(dataAdapter);

Try this

 JSONArray array = jsonObject.getJSONArray("Spinner value");
 allNames.add("Select Your Choice");    
 for (int i = 0; i < array.length(); i++) {
    JSONObject job = array.getJSONObject(i);
    String name = job.getString("spinner_data");
    allNames.add(name);

 }

 ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>
 (MainActivity.this, android.R.layout.simple_spinner_item, allNames);


 spinner.setAdapter(dataAdapter);

  allNames.clear();
  allNames.add("Select Vehicle");
  JSONArray array = jsonObject.getJSONArray("Spinner value");
  for (int i = 0; i < array.length(); i++)
  {
  JSONObject job = array.getJSONObject(i);
  String name = job.getString("spinner_data");
  allNames.add(name);
  }

Do this,

allNames.add("select your choice")

JSONArray array = jsonObject.getJSONArray("Spinner value");
for (int i = 0; i < array.length(); i++) {
JSONObject job = array.getJSONObject(i);
String name = job.getString("spinner_data");
allNames.add(name);}

It will automatically set first index as choice option.