I'm new to Java and Android Development.
Stuck with implementing "SWIPE TO REFRESH" in android. I'm trying to access a method that is in other class. I will highlight the error that android studio gives in blockquote. Help is much appreciated.
MainActivity.java
import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v4.widget.SwipeRefreshLayout;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.Toast;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.HashMap;
public class MainActivity extends AppCompatActivity{
private String TAG = MainActivity.class.getSimpleName();
private SwipeRefreshLayout swipeRefreshLayout;
private ProgressDialog pDialog;
private ListView lv;
// URL to get contacts JSON
private static String url = "http://hooman.com/hoo.php";
ArrayList<HashMap<String, String>> contactList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
contactList = new ArrayList<>();
swipeRefreshLayout = (SwipeRefreshLayout) findViewById(R.id.swiperefresh);
lv = (ListView) findViewById(R.id.list);
swipeRefreshLayout.setOnRefreshListener(this); swipeRefreshLayout.post(new Runnable() { @Override public void run() { swipeRefreshLayout.setRefreshing(true); doInBackground(); } } ); new GetContacts().execute(); } @Override public void onRefresh() { doInBackground(); }
/**
* Async task class to get json by making HTTP call
*/
private class GetContacts extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
// Showing progress dialog
pDialog = new ProgressDialog(MainActivity.this);
pDialog.setMessage("Please wait...");
pDialog.setCancelable(false);
pDialog.show();
}
@Override
protected Void doInBackground(Void... arg0) {
HttpHandler sh = new HttpHandler();
swipeRefreshLayout.setRefreshing(true);
// Making a request to url and getting response
String jsonStr = sh.makeServiceCall(url);
Log.e(TAG, "Response from url: " + jsonStr);
if (jsonStr != null) {
try {
JSONArray contacts = new JSONArray(jsonStr);
// looping through All Contacts
for (int i = 0; i < contacts.length(); i++) {
JSONObject c = contacts.getJSONObject(0);
String kw = c.getString("kw");
String kva = c.getString("kva");
String pf = c.getString("pf");
// tmp hash map for single contact
HashMap<String, String> contact = new HashMap<>();
// adding each child node to HashMap key => value
contact.put("kw", kw);
contact.put("kva", kva);
contact.put("pf", pf);
// adding contact to contact list
contactList.add(contact);
// stopping swipe refresh
swipeRefreshLayout.setRefreshing(false);
}
} catch (final JSONException e) {
Log.e(TAG, "Json parsing error: " + e.getMessage());
Log.e("JSON Parser", "Error parsing data " + e.toString());
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(),
"Json parsing error: " + e.getMessage(),
Toast.LENGTH_LONG)
.show();
}
});
}
} else {
Log.e(TAG, "Couldn't get json from server.");
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(),
"Couldn't get json from server. Check LogCat for possible errors!",
Toast.LENGTH_LONG)
.show();
// stopping swipe refresh
swipeRefreshLayout.setRefreshing(false);
}
});
}
return null;
}
@Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
// Dismiss the progress dialog
if (pDialog.isShowing())
pDialog.dismiss();
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
MainActivity.this, contactList,
R.layout.list_item, new String[]{"kw", "kva",
"pf"}, new int[]{R.id.kw,
R.id.kva, R.id.pf});
lv.setAdapter(adapter);
}
}
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.SwipeRefreshLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/swiperefresh"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<ListView
android:id="@+id/list"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
</android.support.v4.widget.SwipeRefreshLayout>
list_item.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:padding="10dp">
<TextView
android:id="@+id/kw"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:paddingBottom="2dip"
android:paddingTop="6dip"
android:textColor="@color/colorPrimaryDark"
android:textSize="16sp"
android:textStyle="bold" />
<TextView
android:id="@+id/kva"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:paddingBottom="2dip"
android:textColor="@color/colorAccent" />
<TextView
android:id="@+id/pf"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="#5d5d5d"
android:textStyle="bold" />
</LinearLayout>
Thanks in advance.
Firstly, you have circular dependencies. The AsyncTask cannot reference swipeRefreshLayout view in the Activity, and the Activity would need an instance of the task before you could call task.doInBackground() (which you should never do any way). Only need to use execute() and very rarely execute().get()
What you could do is override the postExecute function within the activity
swipeRefreshLayout.post(new Runnable() {
@Override
public void run() {
swipeRefreshLayout.setRefreshing(true);
// Showing progress dialog
final ProgressDialog pDialog = new ProgressDialog(MainActivity.this);
pDialog.setMessage("Please wait...");
pDialog.setCancelable(false);
pDialog.show();
contactList.clear();
new GetContacts() {
@Override
protected void onPostExecute(Void result) {
// stopping swipe refresh
swipeRefreshLayout.setRefreshing(false);
// Dismiss the progress dialog
if (pDialog.isShowing())
pDialog.dismiss();
ListAdapter adapter = new SimpleAdapter(
MainActivity.this, contactList, R.layout.list_item,
new String[]{"kw", "kva", "pf"},
new int[]{R.id.kw,R.id.kva, R.id.pf});
lv.setAdapter(adapter);
}
}.execute();
}
}
);