我试图将数据从服务器推送到共享的首选项，然后将它们拉回，但总是出问题。
这是我的代码
package com.vetdevelopers.vetnetwork;
import android.app.LauncherActivity;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.Toast;
import com.android.volley.AuthFailureError;
import com.android.volley.NetworkError;
import com.android.volley.NoConnectionError;
import com.android.volley.ParseError;
import com.android.volley.Request;
import com.android.volley.Response;
import com.android.volley.ServerError;
import com.android.volley.TimeoutError;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.vetdevelopers.modelclass.ListModification;
import com.vetdevelopers.modelclass.OkHttpToJSON;
import com.vetdevelopers.modelclass.VolleyFunctions;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import okhttp3.Call;
import okhttp3.Callback;
import okhttp3.OkHttpClient;
public class SearchActivity extends AppCompatActivity
{
private Button search_searchButton;
private EditText search_name, search_phone;
private Spinner search_postingArea_spinner, search_district_spinner, search_division_spinner;
private String name = "", phone = "", postingArea = "", district = "", division = "",
POSTING_AREA = "posting_area";
public List<String> list = new ArrayList<String>(); //variable vanish problem , but why?
SharedPreferences sharedPreferences;
SharedPreferences.Editor editor;
final String PREF_NAME = "prefs";
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_search);
search_name = (EditText) findViewById(R.id.search_name);
search_phone = (EditText) findViewById(R.id.search_phone);
search_postingArea_spinner = (Spinner) findViewById(R.id.search_postingArea_spinner);
search_district_spinner = (Spinner) findViewById(R.id.search_district_spinner);
search_division_spinner = (Spinner) findViewById(R.id.search_division_spinner);
search_searchButton = (Button) findViewById(R.id.search_searchButton);
getJSONFromVolley_1_2(ServerConstants.DOCTOR_POSTING_AREA);
Set<String> setEmpty = new HashSet<String>();
setEmpty.add("");
sharedPreferences = getSharedPreferences(PREF_NAME, Context.MODE_PRIVATE);
Set<String> set = sharedPreferences.getStringSet("getJSONFromVolley_1_2",setEmpty);
System.out.println("Here is set : "+set);
System.out.println("List here : "+list);
//editor.remove("getJSONFromVolley_1_2");
//editor.apply();
/*
ArrayAdapter<String> arrayAdapterDivision = new ArrayAdapter<>
(this, android.R.layout.simple_spinner_item, arrayListPostingArea);
arrayAdapterDivision.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
search_postingArea_spinner.setAdapter(arrayAdapterDivision);
*/
search_searchButton.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
/*
name = search_name.getText().toString().trim();
phone = search_phone.getText().toString().trim();
postingArea = search_postingArea_spinner.getSelectedItem().toString();
district = search_district_spinner.getSelectedItem().toString();
division = search_division_spinner.getSelectedItem().toString();
System.out.println("debug now : " + name + " " + phone + " " + postingArea + " " +
district + " " + division + " ");
Bundle bundle = new Bundle();
bundle.putString("name", name);
bundle.putString("phone", phone);
bundle.putString("postingArea", postingArea);
bundle.putString("district", district);
bundle.putString("division", division);
//Intent intent = new Intent(SearchActivity.this,BrowseActivity.class);
//startActivity();
*/
}
});
/*
name=search_name.getText().toString().trim();
phone=search_phone.getText().toString().trim();
postingArea=search_postingArea_spinner.getSelectedItem().toString();
district=search_district_spinner.getSelectedItem().toString();
division=search_division_spinner.getSelectedItem().toString();
*/
}
public void getJSONFromVolley_1_2(String url)
{
StringRequest stringRequest = new StringRequest(Request.Method.POST, url,
new Response.Listener<String>()
{
@Override
public void onResponse(String response)
{
if (response.contains("Connection failed!"))
{
//popupTextView.setText(response);
//mDialog.show();
Toast.makeText(SearchActivity.this, response, Toast.LENGTH_SHORT).show();
}
else if (response.contains("Please check your ID & Password!"))
{
//popupTextView.setText(response);
//mDialog.show();
Toast.makeText(SearchActivity.this, response, Toast.LENGTH_SHORT).show();
}
else if (response.contains("Improper request method!"))
{
//popupTextView.setText(response);
//mDialog.show();
Toast.makeText(SearchActivity.this, response, Toast.LENGTH_SHORT).show();
}
else if (response.contains("Invalid platform!"))
{
//popupTextView.setText(response);
//mDialog.show();
Toast.makeText(SearchActivity.this, response, Toast.LENGTH_SHORT).show();
}
else if (response.contains("sql error"))
{
Toast.makeText(SearchActivity.this, response, Toast.LENGTH_SHORT).show();
}
//server data retrieve code below...
else
{
Set<String> set = new HashSet<String>();
set.add("Select");
try
{
JSONArray jsonArray = new JSONArray(response);
for (int i = 0; i < jsonArray.length(); i++)
{
JSONObject jsonObject = jsonArray.getJSONObject(i);
String output = jsonObject.getString("posting_area");
//debug : for each row - print the two output
//System.out.println("debug : " + (i + 1) + " " + output1);
//unique
if(!set.contains(output) && !output.equals("N/A"))
{
set.add(output);
}
}
}
catch (Exception e)
{
e.printStackTrace();
}
System.out.println("Initial set : "+set);
list.addAll(set);
SharedPreferences sharedPreferences;
SharedPreferences.Editor editor;
String PREF_NAME = "prefs";
sharedPreferences = getSharedPreferences(PREF_NAME, Context.MODE_PRIVATE);
editor = sharedPreferences.edit();
editor.putStringSet("getJSONFromVolley_1_2",set);
editor.apply();
System.out.println("Initial pref : "+sharedPreferences.getStringSet("getJSONFromVolley_1_2",null));
}
}
}, new Response.ErrorListener()
{
@Override
public void onErrorResponse(VolleyError error)
{
if (error instanceof TimeoutError)
{
Toast.makeText(SearchActivity.this, "Timeout error!", Toast.LENGTH_SHORT).show();
}
else if (error instanceof NoConnectionError)
{
Toast.makeText(SearchActivity.this, "No connection error!", Toast.LENGTH_SHORT).show();
}
else if (error instanceof AuthFailureError)
{
Toast.makeText(SearchActivity.this, "Authentication failure error!", Toast.LENGTH_SHORT).show();
}
else if (error instanceof NetworkError)
{
Toast.makeText(SearchActivity.this, "Network error!", Toast.LENGTH_SHORT).show();
}
else if (error instanceof ServerError)
{
Toast.makeText(SearchActivity.this, "Server error!", Toast.LENGTH_SHORT).show();
}
else if (error instanceof ParseError)
{
Toast.makeText(SearchActivity.this, "JSON parse error!", Toast.LENGTH_SHORT).show();
}
}
})
{
@Override
protected Map<String, String> getParams()
{
Map<String, String> params = new HashMap<String, String>();
return params;
}
@Override
public Map<String, String> getHeaders() throws AuthFailureError
{
Map<String, String> headers = new HashMap<String, String>();
headers.put("User-Agent", "VetNetwork"); ////security purpose
return headers;
}
};
MySingleton.getInstance(SearchActivity.this).addToRequestQueue(stringRequest);
}
}
这是logcat：
2019-03-25 05:37:39.961 30919-30919/com.vetdevelopers.vetnetwork
I/System.out: Here is set : []
2019-03-25 05:37:39.961 30919-30919/com.vetdevelopers.vetnetwork
I/System.out: List here : []
2019-03-25 05:37:40.178 30919-30919/com.vetdevelopers.vetnetwork
I/System.out: Initial set : [Noa, Select]
2019-03-25 05:37:40.178 30919-30919/com.vetdevelopers.vetnetwork
I/System.out: Initial pref : [Select, Noa]
我的问题是为什么值从81（或82）行处的变量（甚至从共享首选项）消失？
请告诉我当我尝试从共享首选项中提取数据时出了什么问题？建议我一些更容易解决的问题
答案 0 :(得分：0)
尝试使用由editor.commit()插入的editor.apply()
OR
尝试使用相同的首选项变量。
public class SearchActivity extends AppCompatActivity {
private Button search_searchButton;
private EditText search_name, search_phone;
private Spinner search_postingArea_spinner, search_district_spinner, search_division_spinner;
private String name = "", phone = "", postingArea = "", district = "", division = "", POSTING_AREA = "posting_area";
public List<String> list = new ArrayList<String>(); //variable vanish problem , but why?
SharedPreferences sharedPreferences;
SharedPreferences.Editor editor;
final String PREF_NAME = "prefs";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_search);
search_name = (EditText) findViewById(R.id.search_name);
search_phone = (EditText) findViewById(R.id.search_phone);
search_postingArea_spinner = (Spinner) findViewById(R.id.search_postingArea_spinner);
search_district_spinner = (Spinner) findViewById(R.id.search_district_spinner);
search_division_spinner = (Spinner) findViewById(R.id.search_division_spinner);
search_searchButton = (Button) findViewById(R.id.search_searchButton);
getJSONFromVolley_1_2(ServerConstants.DOCTOR_POSTING_AREA);
Set<String> setEmpty = new HashSet<String>();
setEmpty.add("");
Set<String> set = sharedPreferences.getStringSet("getJSONFromVolley_1_2", setEmpty);
System.out.println("Here is set : " + set);
System.out.println("List here : " + list);
//editor.remove("getJSONFromVolley_1_2");
//editor.apply();
}
public void getJSONFromVolley_1_2(String url) {
StringRequest stringRequest = new StringRequest(Request.Method.POST, url,
new Response.Listener<String>() {
@Override
public void onResponse(String response) {
if (response.contains("Connection failed!")) {
//popupTextView.setText(response);
//mDialog.show();
Toast.makeText(SearchActivity.this, response, Toast.LENGTH_SHORT).show();
} else if (response.contains("Please check your ID & Password!")) {
//popupTextView.setText(response);
//mDialog.show();
Toast.makeText(SearchActivity.this, response, Toast.LENGTH_SHORT).show();
} else if (response.contains("Improper request method!")) {
//popupTextView.setText(response);
//mDialog.show();
Toast.makeText(SearchActivity.this, response, Toast.LENGTH_SHORT).show();
} else if (response.contains("Invalid platform!")) {
//popupTextView.setText(response);
//mDialog.show();
Toast.makeText(SearchActivity.this, response, Toast.LENGTH_SHORT).show();
} else if (response.contains("sql error")) {
Toast.makeText(SearchActivity.this, response, Toast.LENGTH_SHORT).show();
}
//server data retrieve code below...
else {
Set<String> set = new HashSet<String>();
set.add("Select");
try {
JSONArray jsonArray = new JSONArray(response);
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject jsonObject = jsonArray.getJSONObject(i);
String output = jsonObject.getString("posting_area");
//debug : for each row - print the two output
//System.out.println("debug : " + (i + 1) + " " + output1);
//unique
if (!set.contains(output) && !output.equals("N/A")) {
set.add(output);
}
}
} catch (Exception e) {
e.printStackTrace();
}
System.out.println("Initial set : " + set);
list.addAll(set);
sharedPreferences = getSharedPreferences(PREF_NAME, Context.MODE_PRIVATE);
editor = sharedPreferences.edit();
editor.putStringSet("getJSONFromVolley_1_2", set);
editor.commit();
System.out.println("Initial pref : " + sharedPreferences.getStringSet("getJSONFromVolley_1_2", null));
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
if (error instanceof TimeoutError) {
Toast.makeText(SearchActivity.this, "Timeout error!", Toast.LENGTH_SHORT).show();
} else if (error instanceof NoConnectionError) {
Toast.makeText(SearchActivity.this, "No connection error!", Toast.LENGTH_SHORT).show();
} else if (error instanceof AuthFailureError) {
Toast.makeText(SearchActivity.this, "Authentication failure error!", Toast.LENGTH_SHORT).show();
} else if (error instanceof NetworkError) {
Toast.makeText(SearchActivity.this, "Network error!", Toast.LENGTH_SHORT).show();
} else if (error instanceof ServerError) {
Toast.makeText(SearchActivity.this, "Server error!", Toast.LENGTH_SHORT).show();
} else if (error instanceof ParseError) {
Toast.makeText(SearchActivity.this, "JSON parse error!", Toast.LENGTH_SHORT).show();
}
}
}) {
@Override
protected Map<String, String> getParams() {
Map<String, String> params = new HashMap<String, String>();
return params;
}
@Override
public Map<String, String> getHeaders() throws AuthFailureError {
Map<String, String> headers = new HashMap<String, String>();
headers.put("User-Agent", "VetNetwork"); ////security purpose
return headers;
}
};
MySingleton.getInstance(SearchActivity.this).addToRequestQueue(stringRequest);
}
}