**
volley的参数（company_id＆amp;＆amp; branch_id）
等于null虽然我在通过MyRequestQueue_Company之前得到了它的真实数据所以它导致齐射响应是nullpointer异常
为什么myRequestQueue_Drivers中的company_id和branch_id等于null？我该如何解决这个问题？
public class CheckinActivity extends AppCompatActivity implements AdapterView.OnItemSelectedListener {
String company_id, branch_id;
Spinner driver_name_spinner;
private String User_URL = "http://example.com/api/user?token=";
private String Drivers_URL = "http://example.com/api/getDrivers?company_id=1&branch_id=15";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_checkin);
driver_name_spinner = (Spinner) findViewById(R.id.driver_name_spinner);
next = (Button) findViewById(R.id.next);
SharedPreferences sharedPref = getSharedPreferences("userinfo", getApplicationContext().MODE_PRIVATE);
final String token = sharedPref.getString("token", "");
final RequestQueue MyRequestQueue_Company = Volley.newRequestQueue(this);
// GET COMPANY_ID AND BRANCH_ID FORM API
StringRequest MyStringRequest_Company = new StringRequest(Request.Method.GET, User_URL + token, new Response.Listener<String>() {
@Override
public void onResponse(String response) {
Log.d("response", response);
try {
JSONObject jsono = null;
jsono = new JSONObject(response);
JSONObject jarray = jsono.getJSONObject("user");
company_id = jarray.getString("company_id");
branch_id = jarray.getString("branch_id");
Log.d("User Data", "company_id " + company_id + "\tbranch_id " + branch_id);
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() { //Create an error listener to handle errors appropriately.
@Override
public void onErrorResponse(VolleyError error) {
//This code is executed if there is an error.
}
});
MyRequestQueue_Company.add(MyStringRequest_Company);
// CALL ANOTHER WEBSERVICES TO GET DRIVERS DATA
RequestQueue MyRequestQueue_Drivers = Volley.newRequestQueue(getApplicationContext());
StringRequest MyStringRequest_Drivers = new StringRequest(Request.Method.POST, Drivers_URL, new Response.Listener<String>() {
@Override
public void onResponse(String response) {
Log.d("Drivers Response", response);
try {
JSONObject jsono = null;
jsono = new JSONObject(response);
JSONArray jarray = jsono.getJSONArray("Drivers");
List<String> drivers;
drivers = new ArrayList<String>();
for (int i = 0; i < jarray.length(); i++) {
JSONObject newobject = jarray.getJSONObject(i);
driver_name_txt = newobject.getString("name");
Log.d("Driver Name", driver_name_txt);
drivers.add(driver_name_txt);
}
ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(getBaseContext(), android.R.layout.simple_spinner_item, drivers);
dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
driver_name_spinner.setAdapter(dataAdapter);
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() { //Create an error listener to handle errors appropriately.
@Override
public void onErrorResponse(VolleyError error) {
Log.d("Drivers Error",error.toString());
}
}) {
protected Map<String, String> getParams() {
Map<String, String> MyData = new HashMap<String, String>();
// BRANCH_ID AND COMPANY_ID ARE EQUAL NULL !?
MyData.put("branch_id", branch_id);
MyData.put("company_id", company_id);
Log.d("Last User Data", "company_id " + company_id + "\tbranch_id " + branch_id);
return MyData;
}
};
MyRequestQueue_Drivers.add(MyStringRequest_Drivers);
driver_name_spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long l) {
TextView tmpView = (TextView) driver_name_spinner.getSelectedView().findViewById(android.R.id.text1);
tmpView.setTextColor(Color.WHITE);
driver_name_txt = parent.getItemAtPosition(position).toString();
Log.d("driver_name_original", driver_name_txt);
}
@Override
public void onNothingSelected(AdapterView<?> adapterView) {
}
});
答案 0 :(得分：0)
如果你想使用getParams函数，我建议定义一个标志并修改你的函数，如：
@Override
public void onResponse(String response) {
Log.d("response", response);
try {
JSONObject jsono = null;
jsono = new JSONObject(response);
JSONObject jarray = jsono.getJSONObject("user");
company_id = jarray.getString("company_id");
branch_id = jarray.getString("branch_id");
Log.d("User Data", "company_id " + company_id + "\tbranch_id " + branch_id);
requestFinished = true;
} catch (JSONException e) {
e.printStackTrace();
}
}
你的getParams看起来像是：
protected Map<String, String> getParams() {
if(!requestFinished) return null;
Map<String, String> MyData = new HashMap<String, String>();
// BRANCH_ID AND COMPANY_ID ARE EQUAL NULL !?
MyData.put("branch_id", branch_id);
MyData.put("company_id", company_id);
Log.d("Last User Data", "company_id " + company_id + "\tbranch_id " + branch_id);
return MyData;
但我建议你改用Observer pattern。