error with calling class that extends asynctask to run it

error with calling class that extends asynctask to run it - android

I'm using class that extends AsyncTask but I have error at the line that executes the class
I couldn't figure it out
here is the class that includes my main class and the class that extends AsyncTask
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import org.apache.http.NameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import com.example.androidhive.library.JSONParser;
import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.topics_list);
// Hashmap for ListView
TopicsList = new ArrayList<HashMap<String, String>>();
**// Loading products in Background Thread
new LoadAllTopics().execute();**
// Get listview
ListView lv = getListView();
// on seleting single product
// launching Edit Product Screen
lv.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
// getting values from selected ListItem
String tid = ((TextView) view.findViewById(R.id.tid)).getText()
.toString();
/**
* Background Async Task to Load all product by making HTTP Request
* */
class LoadAllTopics extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
#Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(Topics_list.this);
pDialog.setMessage("Loading products. Please wait...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(false);
pDialog.show();
}
/**
* getting All products from url
* */
protected String doInBackground(String... args) {
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
// getting JSON string from URL
JSONObject json = jParser.makeHttpRequest (url_all_topics, "GET", params);
// Check your log cat for JSON reponse
Log.d("All topics: ", json.toString());
try {
// Checking for SUCCESS TAG
int success = json.getInt(TAG_SUCCESS);
if (success == 1) {
// products found
// Getting Array of Products
topics = json.getJSONArray(TAG_TOPICS);
// looping through All Products
for (int i = 0; i < topics.length(); i++) {
JSONObject c = topics.getJSONObject(i);
// Storing each json item in variable
String id = c.getString(TAG_TOPICSID);
String topict = c.getString(TAG_TOPICTITLE);
String username = c.getString(TAG_TOPICAUTHOR);
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put(TAG_TOPICSID, id);
map.put(TAG_TOPICTITLE, topict);
map.put(TAG_TOPICAUTHOR, username);
// adding HashList to ArrayList
TopicsList.add(map);
}
} else {
// no products found
// Launch Add New product Activity
/* Intent i = new Intent(getApplicationContext(),
NewProductActivity.class);
// Closing all previous activities
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(i);*/
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
/**
* After completing background task Dismiss the progress dialog
* **/
protected void onPostExecute(String file_url) {
// dismiss the dialog after getting all products
pDialog.dismiss();
// updating UI from Background Thread
runOnUiThread(new Runnable() {
public void run() {
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
Topics_list.this, TopicsList,
R.layout.list_item, new String[] { TAG_TOPICSID,TAG_TOPICTITLE,
TAG_TOPICAUTHOR},
new int[] { R.id.tid, R.id.name });
// updating listview
setListAdapter(adapter);
}
});
}
}
} });}}
the error is at the bold line
really appreciate your help

In Java you need to write the method inside the class. Put the onCreate inside Class.
public class MainActivity extends Activity {
public void onCreate(Bundle savedInstanceState) {
.....
lv.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
// getting values from selected ListItem
String tid = ((TextView) view.findViewById(R.id.tid)).getText()
.toString();
}
});
.........
}
private class LoadAllTopics extends AsyncTask<String, String, String> {
.....
}
}

Related

How to get specific list item and pass the two values from one activity to another?

I am developing an Android app and I in my SecondActivity I have parsed some JSON values as a listview and I want to open up ThirdActivity when a particular list item is clicked and send the values "name" and "number" to the ThirdActivity.
I have tried by creating an Intent in the OnPostExecute method. But am unable to figure out how to pass the values on to the next activity.
package com.example.acer.videoapp;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
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 SecondActivity extends AppCompatActivity {
private String TAG = MainActivity.class.getSimpleName();
private ProgressDialog pDialog;
private ListView listView1;
Toolbar toolbar1;
String subjectName;
ArrayList<HashMap<String, String>> lessonList;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_second);
//setting title to toolbar
toolbar1 = (Toolbar) findViewById(R.id.toolbar1);
Bundle bundle = getIntent().getExtras();
if(bundle!=null) {
toolbar1.setTitle(bundle.getString("Subject"));
subjectName=toolbar1.getTitle().toString();
}
lessonList = new ArrayList<>();
listView1 = (ListView) findViewById(R.id.list);
new GetLessons().execute();
}
/* Async task class to get json by making HTTP call */
private class GetLessons extends AsyncTask<Void, Void, Void> {
#Override
protected void onPreExecute() {
super.onPreExecute();
// Showing progress dialog
pDialog = new ProgressDialog(SecondActivity.this);
pDialog.setMessage("Please wait...");
pDialog.setCancelable(false);
pDialog.show();
}
#Override
protected Void doInBackground(Void... arg0) {
HttpHandler sh = new HttpHandler();
// Making a request to url and getting response
String url = getResources().getString(R.string.lessons_url, subjectName);
String jsonStr = sh.makeServiceCall(url);
Log.e(TAG, "Response from url: " + jsonStr);
if (jsonStr != null) {
try {
// Getting JSON Array
JSONArray lessons = new JSONArray(jsonStr);
// looping through All lessons
for (int i = 0; i < lessons.length(); i++) {
JSONObject c = lessons.getJSONObject(i);
String number = c.getString("lessonNo");
String name = c.getString("lessonName");
// tmp hash map for single lesson
HashMap<String, String> lesson = new HashMap<>();
// adding each child node to HashMap key => value
lesson.put("number", number);
lesson.put("name", name);
// adding lesson to lesson list
lessonList.add(lesson);
}
} catch (final JSONException e) {
Log.e(TAG, "Json parsing error: " + e.getMessage());
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();
}
});
}
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(
SecondActivity.this, lessonList,R.layout.list_item, new String[]{"number", "name",}, new int[]{R.id.lnumber,R.id.lname});
listView1.setAdapter(adapter);
listView1.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int i, long id) {
Intent intent = new Intent(SecondActivity.this, ThirdActivity.class);
//intent.putExtra("Lesson", listView1.getItemAtPosition(i).toString());
startActivity(intent);
}
});
}
}
}

Can you try this please
listView1.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int i, long id) {
Intent intent = new Intent(SecondActivity.this, ThirdActivity.class);
HashMap<String, String> lesson = lessonList.get(i);
intent.putExtra("number", lesson.get("number"));
intent.putExtra("name", lesson.get("name"));
startActivity(intent);
}});

Similar question has been asked before. You have most of it in place, just use Intent.PutStringArrayListExtra and then getIntent.getStringArrayListExtra to pass objects between the activities.
Check this:
Intent.putExtra List

NullPointerException in Fragment's OnCreateView() [duplicate]

This question already has answers here:
fragment.onCreateView causes null pointer exception
(3 answers)
Closed 7 years ago.
I get a NullPointerException at Fragement's OnCreateView() methods. I've tried several things, but the error keeps showing up. I think the error comes from the listview.
This is my code:
package com.imptmd.charliemacdonald.desleutelaar;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v4.app.ListFragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.HashMap;
public class SlotenFragment extends ListFragment {
private ProgressDialog nDialog;
// URL to get contacts JSON
private static String url = "http://charlenemacdonald.com/sloten.json";
// JSON Node names
private static final String TAG_SLOTEN = "slotenlijst";
private static final String TAG_SLOT = "Slot";
// contacts JSONArray
JSONArray sloten= null;
// Hashmap for ListView
ArrayList<HashMap<String, String>> slotenLijst;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
final View rootView = inflater.inflate(R.layout.fragment_sloten, container, false);
slotenLijst = new ArrayList<HashMap<String, String>>();
ListView lv = (ListView) getView().findViewById(android.R.id.list);
// Listview on item click listener
lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// getting values from selected ListItem
String Slot = ((TextView) rootView.findViewById(R.id.textviewslotnaam))
.getText().toString();
// Starting single contact activity
Intent in = new Intent(getActivity().getApplicationContext(),
SlotInfoScherm1.class);
in.putExtra(TAG_SLOT, Slot);
startActivity(in);
}
});
return rootView;
// Calling async task to get json
}
/**
* Async task class to get json by making HTTP call
* */
private class GetSloten extends AsyncTask<Void, Void, Void> {
#Override
protected void onPreExecute() {
super.onPreExecute();
// Showing progress dialog
nDialog = new ProgressDialog(getActivity());
nDialog.setMessage("Even geduld a.u.b., studenten worden geladen...");
nDialog.setCancelable(false);
nDialog.show();
}
#Override
protected Void doInBackground(Void... arg0) {
// Creating service handler class instance
ServiceHandler sh = new ServiceHandler();
// Making a request to url and getting response
String jsonStr = sh.makeServiceCall(url, ServiceHandler.GET);
Log.d("Response: ", "> " + jsonStr);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
// Getting JSON Array node
sloten = jsonObj.getJSONArray(TAG_SLOTEN);
// looping through All Contacts
for (int i = 0; i < sloten.length(); i++) {
JSONObject c = sloten.getJSONObject(i);
String Slot = c.getString(TAG_SLOT);
// tmp hashmap for single contact
HashMap<String, String> sloten = new HashMap<String, String>();
// adding each child node to HashMap key => value
sloten.put(TAG_SLOT, Slot);
// adding contact to contact list
slotenLijst.add(sloten);
}
} catch (JSONException e) {
e.printStackTrace();
}
} else {
Log.e("ServiceHandler", "Couldn't get any data from the url");
}
return null;
}
#Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
// Dismiss the progress dialog
if (nDialog.isShowing())
nDialog.dismiss();
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(getActivity(), slotenLijst,
R.layout.sloten_info, new String[] { TAG_SLOT}, new int[] { R.id.textviewslotnaam});
setListAdapter(adapter);
}
}
}
Thanks in advance!

In your onCreateView() method, replace
ListView lv = (ListView) getView().findViewById(android.R.id.list);
with
ListView lv = (ListView) rootView.findViewById(android.R.id.list);
The getView() method cannot be called before onCreateView() returns, as getView() in effect returns the View created by onCreateView().

Call findViewById() on the rootView you just inflated, not on the activity.
The view hierarchy you just inflated is not yet a part of the activity view hierarchy.

Android: Convert ListActivity into ListFragment?

Hello I am using the tutorial from androidhive for working with MySQL and so on.
I want to use the following activity as a fragment - but I have to transfer the ListActivity into ListFragment - when I just change the extend from ListActivity to ListFragment different error appear
AllProductsActivity.java
package com.example.androidhive;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import org.apache.http.NameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
public class AllProductsActivity extends ListActivity {
// Progress Dialog
private ProgressDialog pDialog;
// Creating JSON Parser object
JSONParser jParser = new JSONParser();
ArrayList<HashMap<String, String>> productsList;
// url to get all products list
private static String url_all_products = "http://api.androidhive.info/android_connect/get_all_products.php";
// JSON Node names
private static final String TAG_SUCCESS = "success";
private static final String TAG_PRODUCTS = "products";
private static final String TAG_PID = "pid";
private static final String TAG_NAME = "name";
// products JSONArray
JSONArray products = null;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.all_products);
// Hashmap for ListView
productsList = new ArrayList<HashMap<String, String>>();
// Loading products in Background Thread
new LoadAllProducts().execute();
// Get listview
ListView lv = getListView();
// on seleting single product
// launching Edit Product Screen
lv.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// getting values from selected ListItem
String pid = ((TextView) view.findViewById(R.id.pid)).getText()
.toString();
// Starting new intent
Intent in = new Intent(getApplicationContext(),
EditProductActivity.class);
// sending pid to next activity
in.putExtra(TAG_PID, pid);
// starting new activity and expecting some response back
startActivityForResult(in, 100);
}
});
}
// Response from Edit Product Activity
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
// if result code 100
if (resultCode == 100) {
// if result code 100 is received
// means user edited/deleted product
// reload this screen again
Intent intent = getIntent();
finish();
startActivity(intent);
}
}
/**
* Background Async Task to Load all product by making HTTP Request
* */
class LoadAllProducts extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
#Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(AllProductsActivity.this);
pDialog.setMessage("Loading products. Please wait...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(false);
pDialog.show();
}
/**
* getting All products from url
* */
protected String doInBackground(String... args) {
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
// getting JSON string from URL
JSONObject json = jParser.makeHttpRequest(url_all_products, "GET", params);
// Check your log cat for JSON reponse
Log.d("All Products: ", json.toString());
try {
// Checking for SUCCESS TAG
int success = json.getInt(TAG_SUCCESS);
if (success == 1) {
// products found
// Getting Array of Products
products = json.getJSONArray(TAG_PRODUCTS);
// looping through All Products
for (int i = 0; i < products.length(); i++) {
JSONObject c = products.getJSONObject(i);
// Storing each json item in variable
String id = c.getString(TAG_PID);
String name = c.getString(TAG_NAME);
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put(TAG_PID, id);
map.put(TAG_NAME, name);
// adding HashList to ArrayList
productsList.add(map);
}
} else {
// no products found
// Launch Add New product Activity
Intent i = new Intent(getApplicationContext(),
NewProductActivity.class);
// Closing all previous activities
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(i);
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
/**
* After completing background task Dismiss the progress dialog
* **/
protected void onPostExecute(String file_url) {
// dismiss the dialog after getting all products
pDialog.dismiss();
// updating UI from Background Thread
runOnUiThread(new Runnable() {
public void run() {
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
AllProductsActivity.this, productsList,
R.layout.list_item, new String[] { TAG_PID,
TAG_NAME},
new int[] { R.id.pid, R.id.name });
// updating listview
setListAdapter(adapter);
}
});
}
}
}
What I have to change, so I can use that as a fragment?
Edit:
i tried to change the code a little bit following some tutorials on the web...
now it works better, but there is still some problems with onPostExecute...
the doInBackground gets all parameters from mysql. i can track that with debug, but somehow after doInBackground it get's there is an error..
package com.example.androidhive;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import org.apache.http.NameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
public class AllProductsActivity extends ListFragment {
// Progress Dialog
private ProgressDialog pDialog;
// Creating JSON Parser object
JSONParser jParser = new JSONParser();
ArrayList<HashMap<String, String>> productsList;
// url to get all products list
private static String url_all_products = "http://10.0.2.2/android_connect/get_all_products.php";
// JSON Node names
private static final String TAG_SUCCESS = "success";
private static final String TAG_PRODUCTS = "products";
private static final String TAG_PID = "pid";
private static final String TAG_NAME = "name";
// products JSONArray
JSONArray products = null;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
// Hashmap for ListView
// Hashmap for ListView
productsList = new ArrayList<HashMap<String, String>>();
// Loading products in Background Thread
new LoadAllProducts().execute();
return inflater.inflate(R.layout.all_products, container, false);
}
/**
* Background Async Task to Load all product by making HTTP Request
* */
class LoadAllProducts extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
#Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(getActivity());
pDialog.setMessage("Loading products. Please wait...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(false);
pDialog.show();
}
/**
* getting All products from url
* */
protected String doInBackground(String... args) {
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
// getting JSON string from URL
JSONObject json = jParser.makeHttpRequest(url_all_products, "GET", params);
// Check your log cat for JSON reponse
Log.d("All Products: ", json.toString());
try {
// Checking for SUCCESS TAG
int success = json.getInt(TAG_SUCCESS);
if (success == 1) {
// products found
// Getting Array of Products
products = json.getJSONArray(TAG_PRODUCTS);
// looping through All Products
for (int i = 0; i < products.length(); i++) {
JSONObject c = products.getJSONObject(i);
// Storing each json item in variable
String id = c.getString(TAG_PID);
String name = c.getString(TAG_NAME);
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put(TAG_PID, id);
map.put(TAG_NAME, name);
// adding HashList to ArrayList
productsList.add(map);
}
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
/**
* After completing background task Dismiss the progress dialog
* **/
protected void onPostExecute(String file_url) {
// dismiss the dialog after getting all products
pDialog.dismiss();
// updating UI from Background Thread
getActivity().runOnUiThread(new Runnable() {
public void run() {
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
getActivity(), productsList,
R.layout.list_item, new String[] { TAG_PID,
TAG_NAME},
new int[] { R.id.pid, R.id.name });
// updating listview
setListAdapter(adapter);
}
});
}
}
}

You must create fragment in FragmentActivity. All code you need is below
MainActivity.java
public class MainActivity extends FragmentActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.fragment_activity);
int index=0;
MyListFragment f = MyListFragment.newInstance(index);
FragmentTransaction ft = getSupportFragmentManager()
.beginTransaction();
ft.replace(R.id.mylist, f);
ft.commit();
}//end oncreate
}//end activity
Layout fragment_activity.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:baselineAligned="false"
android:layout_height="match_parent"
android:orientation="horizontal" >
<FrameLayout
android:id="#+id/mylist"
android:layout_weight="1"
android:layout_width="0px"
android:layout_height="match_parent" />
</LinearLayout>
MyListFragment.java
public class MyListFragment extends ListFragment {
public static MyListFragment newInstance(int index) {
MyListFragment f = new MyListFragment();
return f;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.layout_mylist, container, false);
//read products from web and list
//productsList = new ArrayList<HashMap<String, String>>();
//new LoadProducts().execute();
return v;
}
//end oncreateview
class LoadProducts extends AsyncTask<String, String, String> {
#Override
protected void onPreExecute() {
super.onPreExecute();
}
protected String doInBackground(String... args) {
return null;
}
protected void onPostExecute(String file_url) {
}
}
//end LoadProducts
}
layout_mylist.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical" >
<TextView
android:id="#+id/details"
android:text="some text"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#drawable/white"
android:textColor="#drawable/black"
android:textStyle="bold"
android:paddingTop="6dip"
android:paddingLeft="6dip"
android:textAppearance="?android:attr/textAppearanceMedium" />
<ListView
android:id="#android:id/list"
android:layout_width="fill_parent"
android:layout_height="wrap_content"/>
</LinearLayout>

How can I delete an item from an online database via android application?

I started to develop Android recently and I'm having difficulty in solving a thing probably much simpler than what I think.
I am creating a CRUD application that communicates with an online database, I can read and enter data, unfortunately I can't delete and modify the list once it is created.
To manage the data that use JSON and the row in the list that I add is made up of three fields: animal_id, animal_name, animal_type.
The activity data on which I read and on which I want to implement methods to modify and delete via listener is formed by the following code:
import java.sql.Array;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.AlertDialog;
import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
public class ListAnimalActivity extends ListActivity {
ArrayList<HashMap<String,?>> animalList;
JSONParser jParser = new JSONParser();
JSONArray animals = null;
Button button_add;
private static String url_read = "http://example.com/list_animals.php";
private static String url_delete = "http://example.com/delete_animal.php";
private static final String TAG_SUCCESS = "success";
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
load_ListAnimalActivity();
}
public void onResume(){
super.onResume();
load_ListAnimalActivity();
}
private void load_ListAnimalActivity(){
setContentView(R.layout.activity_list_animal);
animalList = new ArrayList<HashMap<String,?>>();
new Read_Object().execute();
final ListView listView = (ListView)findViewById(android.R.id.list);
final ListAdapter adapter = new SimpleAdapter(
ListAnimalActivity.this, animalList,
R.layout.row_list, new String[] { "animal_id",
"animal_name","animal_type"},
new int[] { R.id.animal_id, R.id.animal_name,R.id.animal_type });
listView.setAdapter(adapter);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener(){
#Override
public void onItemClick(AdapterView<?> parent, View view, final int position, long id) {
AlertDialog.Builder adb = new AlertDialog.Builder(ListAnimalActivity.this);
adb.setTitle("Attenzione!");
adb.setMessage("Vuoi eliminare l\'elemento \"" + animalList.get(position)+ "\" ?");
final int posizione = position;
adb.setNegativeButton("Annulla",new AlertDialog.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {}
});
adb.setPositiveButton("Elimina", new AlertDialog.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
new Delete_Object().execute();
}
});
adb.show();
}
});
button_add = (Button)findViewById(R.id.button_add);
button_add.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startActivity(new Intent(ListAnimalActivity.this,CRUDAnimalActivity.class));
}
});
}
class Read_Object extends AsyncTask<String, String, String> {
private ProgressDialog progressMessage = new ProgressDialog(ListAnimalActivity.this);
#Override
protected void onPreExecute() {
super.onPreExecute();
progressMessage.setMessage("Loading ...");
progressMessage.setIndeterminate(false);
progressMessage.setCancelable(false);
progressMessage.show();
}
protected String doInBackground(String... args) {
List params = new ArrayList();
JSONObject json = jParser.makeHttpRequest(url_read, "POST", params);
try{
Log.d("Animals: ", json.toString());
} catch (NullPointerException e){
e.printStackTrace();
}
try {
int success = json.getInt(TAG_SUCCESS);
if (success == 1) {
animals = json.getJSONArray("animals");
for (int i = 0; i < animals.length(); i++) {
JSONObject c = animals.getJSONObject(i);
String id = c.getString("animal_id");
String name = c.getString("animal_name");
String type = c.getString("animal_type");
HashMap map = new HashMap();
map.put("animal_id", id);
map.put("animal_name", name);
map.put("animal_type", type);
animalList.add(map);
}
}
} catch (JSONException e) {
e.printStackTrace();
} catch (NullPointerException e){
e.printStackTrace();
}
return null;
}
protected void onPostExecute(String file_url) {
progressMessage.dismiss();
runOnUiThread(new Runnable() {
public void run() {
ListAdapter adapter = new SimpleAdapter(
ListAnimalActivity.this, animalList,
R.layout.row_list, new String[] { "animal_id",
"animal_name","animal_type"},
new int[] { R.id.animal_id, R.id.animal_name,R.id.animal_type });
setListAdapter(adapter);
}
});
}
}
class Delete_Object extends AsyncTask<String, String, String>{
private ProgressDialog progressMessage = new ProgressDialog(ListAnimalActivity.this);
#Override
protected void onPreExecute() {
super.onPreExecute();
progressMessage.setMessage("Deleting ...");
progressMessage.setIndeterminate(false);
progressMessage.setCancelable(false);
progressMessage.show();
}
protected String doInBackground(String... args) {
/*
Code to delete
*/
return null;
}
protected void onPostExecute(String file_url){
}
}
}
When i click on a list Item, the listener show me the object in this format:
{animal_type=firstType, animal_name=firstName, animal_id=1}
So my question is:
How can I collect only animal_id from the array animalList > ?

Your animalList is an array list with HashMaps as its elements, so when you call animalList.get(position), it will return a HashMap. To retrieve an animal_id just use :
(animalList.get(position)).get(animal_id).toString();

you have to create a Modelclass/Pojo Class (Private variable and getters and setters) for Animals,
ArrayList<AnimalModel> animalsArrayList = new ArrayList<AnimalModel>();
add the Animals object/data to animalsArrayList and listview.setAdapter(animalsArrayList);
then
listView.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// TODO Auto-generated method stub
Object object = speakerListView.getItemAtPosition(position);
AnimalModel animals_data = (AnimalModel) object;
id = animals_data.getAnimal_id()
// call delete Async with thid Id
}
});

You code looks pretty messy. If I were you I would create a Custom Adapter that extends the base adapter and takes as a parameter either a hashmap or a list that you pass in the constructor. There you can have different listeners. Also if you want to notify the activity you can have the "luxury" to pass an interface as a parameter and notify the activity when something changes.
Regarding the json part, I would create two new classes, one which is a Thread Manager that receives tasks and handles them further and another class where u make the http calls and the json parsing.
I have done a similar application that receives data from a nebula interface and displays them to the user.

Example Code Works as Activity but not as Fragment

I'm fairly new to Android development. I'm still learning and getting along with example codes i can find online.
I'm having a bit of trouble trying to get this example code to work in a fragment Activity, however it works seamlessly as an Activity. I don't know what i'm missing.
Eclipse keeps Highlighting unusual parts of the code, making it difficult to debug
any help would be greatly appreciated.
I'll post both working code and one with errors :errors will be Bold text
//Working code
package com.example.androidhive;
import java.util.ArrayList;
import java.util.List;
import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
public class NewProductActivity extends Activity {
// Progress Dialog
private ProgressDialog pDialog;
JSONParser jsonParser = new JSONParser();
EditText inputName;
EditText inputPrice;
EditText inputDesc;
// url to create new product
private static String url_create_product = "http://10.0.2.2/android_connect/create_product.php";
// JSON Node names
private static final String TAG_SUCCESS = "success";
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.add_product);
// Edit Text
inputName = (EditText) findViewById(R.id.inputName);
inputPrice = (EditText) findViewById(R.id.inputPrice);
inputDesc = (EditText) findViewById(R.id.inputDesc);
// Create button
Button btnCreateProduct = (Button) findViewById(R.id.btnCreateProduct);
// button click event
btnCreateProduct.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
// creating new product in background thread
new CreateNewProduct().execute();
}
});
}
/**
* Background Async Task to Create new product
* */
class CreateNewProduct extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
#Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(NewProductActivity.this);
pDialog.setMessage("Creating Product..");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
/**
* Creating product
* */
protected String doInBackground(String... args) {
String name = inputName.getText().toString();
String price = inputPrice.getText().toString();
String description = inputDesc.getText().toString();
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("name", name));
params.add(new BasicNameValuePair("price", price));
params.add(new BasicNameValuePair("description", description));
// getting JSON Object
// Note that create product url accepts POST method
JSONObject json = jsonParser.makeHttpRequest(url_create_product,
"POST", params);
// check log cat fro response
Log.d("Create Response", json.toString());
// check for success tag
try {
int success = json.getInt(TAG_SUCCESS);
if (success == 1) {
// successfully created product
Intent i = new Intent(getApplicationContext(), AllProductsActivity.class);
startActivity(i);
// closing this screen
finish();
} else {
// failed to create product
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
/**
* After completing background task Dismiss the progress dialog
* **/
protected void onPostExecute(String file_url) {
// dismiss the dialog once done
pDialog.dismiss();
}
}
}
// Non Working Code, after turning it into a fragment
package com.example.androidhive;
import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import java.util.ArrayList;
import java.util.List;
import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
public class AddProductsFragment extends **Fragment** {
public final int ARG_SECTION_NUMBER = 0;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.add_product,
container, false);
return rootView;
}
// Progress Dialog
private ProgressDialog pDialog;
JSONParser jsonParser = new JSONParser();
EditText inputName;
EditText inputPrice;
EditText inputDesc;
// url to create new product
private static String url_create_product = "http://10.0.2.2/android_connect/create_product.php";
// JSON Node names
private static final String TAG_SUCCESS = "success";
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
**setContentView**(R.layout.add_product);
// Edit Text
inputName = (EditText) **findViewById**(R.id.inputName);
inputPrice = (EditText) **findViewById**(R.id.inputPrice);
inputDesc = (EditText) **findViewById**(R.id.inputDesc);
// Create button
Button btnCreateProduct = (Button) **findViewById**(R.id.btnCreateProduct);
// button click event
btnCreateProduct.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
// creating new product in background thread
new CreateNewProduct().execute();
}
});
}
/**
* Background Async Task to Create new product
* */
class CreateNewProduct extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
#Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(**AddProductFragment**.this);
pDialog.setMessage("Creating Product..");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
/**
* Creating product
* */
protected String doInBackground(String... args) {
String name = inputName.getText().toString();
String price = inputPrice.getText().toString();
String description = inputDesc.getText().toString();
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("name", name));
params.add(new BasicNameValuePair("price", price));
params.add(new BasicNameValuePair("description", description));
// getting JSON Object
// Note that create product url accepts POST method
JSONObject json = jsonParser.makeHttpRequest(url_create_product,
"POST", params);
// check log cat fro response
Log.d("Create Response", json.toString());
// check for success tag
try {
int success = json.getInt(TAG_SUCCESS);
if (success == 1) {
// successfully created product
Intent i = new Intent(**getApplicationContext**(), AllProductsActivity.class);
startActivity(i);
// closing this screen
**finish**();
} else {
// failed to create product
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
/**
* After completing background task Dismiss the progress dialog
* **/
protected void onPostExecute(String file_url) {
// dismiss the dialog once done
pDialog.dismiss();
}
}
}
// I might be failing to import some assets, thing is i don't know where to start in correcting this.
Thanks again for your time and help.
kind Regards
Edem

In fragments, you should get the reference to your visual elements in onCreateView() method, for example:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.add_product, container, false);
inputName = (EditText) view.findViewById(R.id.inputName);
return view;
}
If you want to use findViewById() after onCreateView() as already been called (later in the fragment's lifecycle), you can use getView() method:
inputName = (EditText) getView().findViewById(R.id.inputName);

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