我使用volley库来获取RcyclerView中的json数据但是当我转到活动时，不要第一次显示任何数据，我应该回到之前的活动并再次转到它以显示数据。我吗？
public class EventActivity extends AppCompatActivity {
private String jsonResponseEventName;
private String jsonResponseEventStartDate;
private String jsonResponseEventEndDate;
private String jsonResponseEventTime;
private String jsonResponseEventLocation;
private String jsonResponseEventOwner;
private String jsonResponseEventDes;
private String jsonResponseEventPic;
//--------------------------------
private ProgressDialog pDialog;
//-------------------------
private MyDatabase db;
//----------------------------
private String urlJsonArray="http://kazeroon.mosbate16.com/event.php";
private static String TAG = ListActivity.class.getSimpleName();
static List<String> eventNameItems = new ArrayList<String>();
static List<String> eventStartDateItems = new ArrayList<String>();
static List<String> eventEndDateItems = new ArrayList<String >();
static List<String> eventTimeItems = new ArrayList<String>();
static List<String> eventLocationItems = new ArrayList<String>();
static List<String> eventOwnerItems = new ArrayList<String>();
static List<String> eventDesItems = new ArrayList<String>();
static List<String> eventPicOItems = new ArrayList<String>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_event);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
//------------
db=new MyDatabase(this);
pDialog = new ProgressDialog(EventActivity.this);
pDialog.setMessage("Please wait...");
pDialog.setCancelable(false);
new GetData().execute();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_event, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_send_event){
Intent sendEventActivity =new Intent(EventActivity.this,SendEventActivity.class);
startActivity(sendEventActivity);
return true;
}
if (id == R.id.action_exit) {
finish();
return true;
}
return super.onOptionsItemSelected(item);
}
public void setaddapter(){
//tarif class adapter recyclview
RecyclerView recyclerViewlist=(RecyclerView) findViewById(R.id.eventList);
recyclerViewlist.setAdapter(new RVAdapterEvent(this, eventNameItems, eventStartDateItems, eventEndDateItems,
eventTimeItems, eventLocationItems, eventOwnerItems, eventDesItems, eventPicOItems));
//tarif layout maneger baraye tarif noe nemayesh
recyclerViewlist.setLayoutManager(new LinearLayoutManager(this));
}
private class GetData extends AsyncTask<String,Integer,String >{
@Override
protected void onPreExecute() {
super.onPreExecute();
showpDialog();
}
@Override
protected String doInBackground(String ... params) {
JsonArrayRequest req = new JsonArrayRequest(urlJsonArray,
new Response.Listener<JSONArray>() {
@Override
public void onResponse(JSONArray response) {
Log.d(TAG, response.toString());
try {
// Parsing json array response
// loop through each json object
eventNameItems.clear();
eventStartDateItems.clear();
eventEndDateItems.clear();
eventTimeItems.clear();
eventLocationItems.clear();
eventOwnerItems.clear();
eventDesItems.clear();
eventPicOItems.clear();
db.Querry("DELETE FROM tbl_event");
for (int i = 0; i < response.length(); i++) {
JSONObject person = (JSONObject) response.get(i);
String name = person.getString("name");
String startdate = person.getString("startdate");
String enddate = person.getString("enddate");
String time = person.getString("time");
String location = person.getString("location");
String owner = person.getString("owner");
String des = person.getString("des");
String pic = person.getString("pic");
db.Querry("INSERT INTO tbl_event ( name , startdate , enddate , time , location , owner , des , pic ) " +
"VALUES ('"+name+"','"+startdate+"','"+enddate+"','"+time+"','"+location+"','"+owner+"','"+des+"','"+pic+"' )");
// Toast.makeText(ListActivity.this,name,Toast.LENGTH_SHORT).show();
jsonResponseEventName = name;
jsonResponseEventStartDate = startdate;
jsonResponseEventEndDate = enddate;
jsonResponseEventTime= time;
jsonResponseEventLocation=location;
jsonResponseEventOwner = owner;
jsonResponseEventDes = des;
jsonResponseEventPic = pic;
eventNameItems.add(jsonResponseEventName);
eventStartDateItems.add(jsonResponseEventStartDate);
eventEndDateItems.add(jsonResponseEventEndDate);
eventTimeItems.add(jsonResponseEventTime);
eventLocationItems.add(jsonResponseEventLocation);
eventOwnerItems.add(jsonResponseEventOwner);
eventDesItems.add(jsonResponseEventDes);
eventPicOItems.add(jsonResponseEventPic);
}
} catch (JSONException e) {
e.printStackTrace();
Toast.makeText(getApplicationContext(),
"Error: " + e.getMessage(),
Toast.LENGTH_LONG).show();
Toast.makeText(getApplicationContext(),
"ارتباط با سرور برقرار نشد،آخرین اطلاعات دریافتی نمایش داده می شود",
Toast.LENGTH_LONG).show();
//---------------------------------------------------------------------
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
VolleyLog.d(TAG, "Error: " + error.getMessage());
Toast.makeText(getApplicationContext(),
error.getMessage(), Toast.LENGTH_SHORT).show();
Toast.makeText(getApplicationContext(),
"ارتباط با سرور برقرار نشد،آخرین اطلاعات دریافتی نمایش داده می شود",
Toast.LENGTH_LONG).show();
}
});
// Adding request to request queue
AppController.getInstance().addToRequestQueue(req);
return null;
}
@Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
hidepDialog();
runOnUiThread(new Runnable() {
@Override
public void run() {
setaddapter();
}
});
}
}
private void showpDialog() {
if (!pDialog.isShowing())
pDialog.show();
}
private void hidepDialog() {
if (pDialog.isShowing())
pDialog.dismiss();
}
}
答案 0 :(得分：0)
由于您使用的是异步方法，因此必须通知数据集已更改。
只需在adapter.notifyDataSetChanged()方法中致电setAddapter()。