Develop Reference

arraymap is better than sparse array to memorise some data catched from a JSON file?

I had wrote a code which use a parse to catch some data from a JSON file but i don't know what kind of structure is better between the sparse array or the array map for memorise these data ?
I had used a array map but I don't know if it's too wasted on so little data data.
public class MainActivity extends AppCompatActivity {
private ProgressDialog pd;
private String TAG = MainActivity.class.getSimpleName();
public ArrayMap<Integer, ValoriDiSueg> ArrayDati = new ArrayMap<>();
Button buttonProg;
TextView textViewProg;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
buttonProg = (Button) findViewById(R.id.button);
textViewProg = (TextView) findViewById(R.id.textView);
buttonProg.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
new JsonCLASS().execute("https://samples.openweathermap.org/data/2.5/weather?q=London,uk&appid=b6907d289e10d714a6e88b30761fae22");
}
});
}
private class JsonCLASS extends AsyncTask<String, String, String> {
#Override
protected void onPreExecute() {
super.onPreExecute();
pd = new ProgressDialog(MainActivity.this);
pd.setMessage("Please wait");
pd.setCancelable(false);
pd.show();
}
#Override
protected String doInBackground(String... params) {
HttpURLConnection connection = null;
BufferedReader reader = null;
try {
URL url = new URL(params[0]);
connection = (HttpURLConnection) url.openConnection();
connection.connect();
InputStream stream = connection.getInputStream();
reader = new BufferedReader(new InputStreamReader(stream));
StringBuffer buffer = new StringBuffer();
String line = "";
while ((line = reader.readLine()) != null) {
buffer.append(line + "\n");
Log.d("Response: ", "> " + line); //here u ll get whole response...... :-)
}
return buffer.toString();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (connection != null) {
connection.disconnect();
}
try {
if (reader != null) {
reader.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
return null;
}
The parse of these data
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
try {
JSONObject jsonObject = new JSONObject(result);
JSONArray Arr = new JSONArray(jsonObject.getString("weather"));
for (int i = 0; i < Arr.length(); i++){
JSONObject jsonPart = Arr.getJSONObject(i);
ArrayDati.put(i,new ValoriDiSueg( jsonPart.getString("main"), jsonPart.getString("description")));
//ArrayDati.put(i,new ValoriDiSueg("description : "+ jsonPart.getString("description")));
textViewProg.setText(textViewProg.getText()+"main : "+ ArrayDati.get(i).Main +"\n"+textViewProg.getText()+"description : "+ ArrayDati.get(i).Description );
}
} catch (Exception e ){
e.printStackTrace();
}
if (pd.isShowing()) {
pd.dismiss();
}
}
}
}
And I created a class:
public class ValoriDiSueg {
String Main;
String Description;
public ValoriDiSueg(String main, String description) {
this.Main = main;
this.Description = description;
}
}
any suggestions??

In simple:
If your key is int or long, you should use SparseArray, SparseLongArray as it will not boxing/un-boxing the key value when operates. Also, it provides similar classes for int/long values as long as the key is int/long.
If you key is not int nor long, such as an object or String, you should use ArrayMap instead as it will handle the conflicts of key hashes.
There are no much performance and memory usage difference between these two class as they are all requires O(log n) to search and O(n) to insert/delete (in most cases).

Getting Data from JSON?

I want to get the username from this
Json url.
I have this code but it doesn't let me get the data saying
Json parsing error
Here is the code:
HttpHandler.java
public class HttpHandler {
private static final String TAG = HttpHandler.class.getSimpleName();
public HttpHandler() {
}
public String makeServiceCall(String reqUrl) {
String response = null;
try {
URL url = new URL(reqUrl);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
// read the response
InputStream in = new BufferedInputStream(conn.getInputStream());
response = convertStreamToString(in);
} catch (MalformedURLException e) {
Log.e(TAG, "MalformedURLException: " + e.getMessage());
} catch (ProtocolException e) {
Log.e(TAG, "ProtocolException: " + e.getMessage());
} catch (IOException e) {
Log.e(TAG, "IOException: " + e.getMessage());
} catch (Exception e) {
Log.e(TAG, "Exception: " + e.getMessage());
}
return response;
}
private String convertStreamToString(InputStream is) {
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line;
try {
while ((line = reader.readLine()) != null) {
sb.append(line).append('\n');
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return sb.toString();
}
}
MainActivity.java
public class MainActivity extends AppCompatActivity {
private String TAG = MainActivity.class.getSimpleName();
private ProgressDialog pDialog;
private ListView lv;
// URL to get contacts JSON
private static String url = "https://someLink";
ArrayList<HashMap<String, String>> contactList;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
contactList = new ArrayList<>();
lv = (ListView) findViewById(R.id.list);
new GetContacts().execute();
}
/**
* 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();
// Making a request to url and getting response
String jsonStr = sh.makeServiceCall(url);
Log.e(TAG, "Response from url: " + jsonStr);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
// Getting JSON Array node
JSONArray contacts = jsonObj.getJSONArray("");
// looping through All Contacts
for (int i = 0; i < contacts.length(); i++) {
JSONObject c = contacts.getJSONObject(i);
String name = c.getString("username");
// tmp hash map for single contact
HashMap<String, String> contact = new HashMap<>();
// adding each child node to HashMap key => value
contact.put("username", name);
// adding contact to contact list
contactList.add(contact);
}
} 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(
MainActivity.this, contactList,
R.layout.list_item, new String[]{"username"}, new int[]{R.id.name});
lv.setAdapter(adapter);
}
}
}
This is an example i found on google and tried to change it a bit in my needs.I've put an empty JsonArray.I also tried other examples but i can't understand what is going wrong.
**
> New question
If my url is like this?What is the difference with the other?
**

You don't have an array to parse in the output. Your URL giving you an Object. Your code should be something like this
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
String name = jsonObj.getString("username");
//... now use the whereever you want
}
catch (final JSONException e) {
//... put your error log
}

Please edit your code in MainActivity to get the username from json string as follows :
if(jsonStr!=null)
{
JSONObject jsonObj = new JSONObject(jsonStr);
if(jsonObj !=null)
{
String name = jsonObj .getString("username");
}
}

i suggest you to use this one.
public class HttpGetResources extends AsyncTask<String, Void, Object> {
#SuppressLint("StaticFieldLeak")
private ProgressBar progressBar;
private static final String RAW_DATE_FORMAT = "yyyy-MM-dd'T'HH:mm:ss.SSSz";
private String urlString;
private String apiName;
private Class Response_Class;
private static final Gson GSON = new GsonBuilder().setDateFormat(RAW_DATE_FORMAT).create();
private Context context;
public HttpGetResources(Context context,Class Response_Class, String apiName, String urlString) {
this.Response_Class = Response_Class;
this.apiName = apiName;
this.urlString = urlString;
this.context=context;
}
#Override
protected void onPreExecute() {
super.onPreExecute();
}
#Override
protected void onPostExecute(Object response) {
super.onPostExecute(response);
}
HttpURLConnection conn = null;
OutputStreamWriter out = null;
Object result = null;
BufferedReader buffer = null;
final ExecutorService executor = Executors.newCachedThreadPool(Executors.defaultThreadFactory());
static public Future<Object> future;
#SuppressWarnings("unchecked")
#Override
protected Object doInBackground(final String... params) {
// JsonObject res=null;
future = executor.submit(new Callable<Object>() {
#Override
public Object call() throws IOException {
try {
URL url = new URL(urlString + apiName);
conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("POST");
conn.setRequestProperty("Content-Type", "application/json;charset=UTF-8");
conn.setConnectTimeout(3000);
conn.setReadTimeout(15000);
conn.setDoInput(true);
conn.setDoOutput(true);
out = new OutputStreamWriter(conn.getOutputStream());
out.write(params[0]);
out.flush();
out.close(); out=null;
buffer = new BufferedReader(new InputStreamReader(conn.getInputStream()));
// res= GSON.fromJson(buffer, JsonObject.class);
// result = new Gson().fromJson(res.toString(), Response_Class);
result = GSON.fromJson(buffer, Response_Class);
buffer.close(); buffer=null;
// result = new Gson().fromJson(res.toString(), Response_Class);
} catch (Exception e) {
//
} finally {
if (buffer!=null) {
try {
buffer.close();
} catch (Exception e) { //
}
}
if (out != null) {
try {
out.close();
} catch (Exception e) { //
}
}
if (conn != null) {
conn.disconnect();
}
}
return result;
}
});
try {
result = future.get(10, TimeUnit.SECONDS);
} catch (Exception ignored) {
}
return result;
}
}
--and call method--
public synchronized Object HttpGetRes(final Object REQUEST_CLASS, final Class RESPONSE_CLASS, final String
API_NAME, final String URL) {
if(isNetworkAvailable()) {
response = null;
try {
Log.e(API_NAME, "url: " + URL);
Log.e(REQUEST_CLASS.getClass().getSimpleName(), new Gson().toJson(REQUEST_CLASS));
HttpGetResources resource = new HttpGetResources(BaseContext,RESPONSE_CLASS, API_NAME,
URL);
response = resource.execute(new Gson().toJson(REQUEST_CLASS)).get();
} catch (InterruptedException | ExecutionException e) {
e.printStackTrace();
}
if (response != null) {
String x = new Gson().toJson(response);
Log.e(RESPONSE_CLASS.getSimpleName(), x);
return response;
} else {
}
}
return null;
}

Try to use GSON library in the future, it will auto convert the JSON object to a java object automatically for you. This will be useful to avoid parsing complex JSON objects or JSON arrays. https://github.com/google/gson

listview not showing items android

I am have sql DB and I am trying to display queried values in a listView. I created a custom adapter for the listView. problem is
I am not able to see any data displayed on my listView.
code of main
public class _songs_playlist extends AppCompatActivity {
ArrayList<songsarray> listofsoongs = new ArrayList<songsarray>();
private static int SPLASH_TIME_OUT=2000;
AlertDialog alertDialog;
private boolean loggedIn = false;
String type;
String result;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity__songs_playlist);
new JSONParse().execute();
MyCustomAdapterSongs itemsAdapter = new MyCustomAdapterSongs(this, listofsoongs);
ListView listView = (ListView) findViewById(R.id.listView1);
listView.setAdapter(itemsAdapter);
itemsAdapter.notifyDataSetChanged();
}
private class JSONParse extends AsyncTask<String, String, JSONObject> {
private ProgressDialog pDialog;
#Override
protected void onPreExecute() {
super.onPreExecute();
alertDialog=new AlertDialog.Builder(_songs_playlist.this).create();
alertDialog.setTitle("Upadting Data");
pDialog = new ProgressDialog(_songs_playlist.this);
pDialog.setMessage("Getting Data ...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
#Override
protected JSONObject doInBackground(String... args) {
HTTPHandler sh = new HTTPHandler();
String login_URL = "http://2f179dfb.ngrok.io/getsong.php";
try {
//Fetching the boolean value form sharedpreferences
URL url = new URL(login_URL);
HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
httpURLConnection.setRequestMethod("POST");
httpURLConnection.setDoOutput(true);
httpURLConnection.setDoInput(true);
InputStream inputStream = httpURLConnection.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "iso-8859-1"));
result = "";
String line = "";
while ((line = bufferedReader.readLine()) != null) {
result += line;
}
bufferedReader.close();
inputStream.close();
httpURLConnection.disconnect();
Log.e("RESULT", result);
JSONObject jsonObject = new JSONObject(result);
JSONArray result1 = jsonObject.getJSONArray("result");
for (int i = 0; i < result1.length(); i++) {
JSONObject c = result1.getJSONObject(i);
String id = c.getString("songID");
String names = c.getString("songName");
String ss = c.getString("singerName");
listofsoongs.add(new songsarray(ss,id,names));
}
return jsonObject;
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(JSONObject json) {
pDialog.dismiss();
if(true)
{
}
else
{
}
}
}
}
code of custom array adapter
public class MyCustomAdapterSongs extends ArrayAdapter<songsarray> {
Context context;
ArrayList<songsarray> items;
public MyCustomAdapterSongs(Activity context, ArrayList<songsarray> songsarrays) {
super(context, 0, songsarrays);
this.context=context;
this.items=songsarrays;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
View listItemView = convertView;
if (listItemView == null) {
listItemView = LayoutInflater.from(getContext()).inflate(
R.layout.itemlist, parent, false);
}
TextView nameTextView = (TextView) listItemView.findViewById(R.id.textView1);
nameTextView.setText(currentAndroidFlavor.getSingername());
Log.e("hhhh", nameTextView.getText().toString());
TextView numberTextView = (TextView) listItemView.findViewById(R.id.textView2);
numberTextView.setText(currentAndroidFlavor.getSongname());
Log.e("jjjj", numberTextView.getText().toString());
CheckBox ch=(CheckBox)listItemView.findViewById(R.id.checkBox1);
ch.setSelected(currentAndroidFlavor.isSelected());
return listItemView;
}
#Override
public int getCount() {
if(items == null)
return 0;
return items.size();
}
#Override
public songsarray getItem(int i) {
return items.get(i);
}
}

Call itemsAdapter.notifyDataSetChanged() within onPostExecute.
Your list is empty until the AsyncTask finishes there.
You'll have to make the adapter a member variable of the Activity class

As in your code I can see you are updating the list in doInBackground but you are not notifying the adapter for the changes.
In onPostExecute method you need to call itemsAdapter.notifyDataSetChanged() and make sure it you are not calling it inside doInBackground as in background thread you can't to UI related work.

Check the EDITS in this code snippet
`
public class _songs_playlist extends AppCompatActivity {
ArrayList<songsarray> listofsoongs = new ArrayList<songsarray>();
private static int SPLASH_TIME_OUT=2000;
AlertDialog alertDialog;
private boolean loggedIn = false;
String type;
String result;
//EDIT 1: Make these member variables
MyCustomAdapterSongs itemsAdapter;
ListView listView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity__songs_playlist);
//EDIT 2: get references your views before AsyncTask
listView = (ListView) findViewById(R.id.listView1);
new JSONParse().execute();
}
private class JSONParse extends AsyncTask<String, String, JSONObject> {
private ProgressDialog pDialog;
#Override
protected void onPreExecute() {
super.onPreExecute();
alertDialog=new AlertDialog.Builder(_songs_playlist.this).create();
alertDialog.setTitle("Upadting Data");
pDialog = new ProgressDialog(_songs_playlist.this);
pDialog.setMessage("Getting Data ...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
#Override
protected JSONObject doInBackground(String... args) {
HTTPHandler sh = new HTTPHandler();
String login_URL = "http://2f179dfb.ngrok.io/getsong.php";
try {
//Fetching the boolean value form sharedpreferences
URL url = new URL(login_URL);
HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
httpURLConnection.setRequestMethod("POST");
httpURLConnection.setDoOutput(true);
httpURLConnection.setDoInput(true);
InputStream inputStream = httpURLConnection.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "iso-8859-1"));
result = "";
String line = "";
while ((line = bufferedReader.readLine()) != null) {
result += line;
}
bufferedReader.close();
inputStream.close();
httpURLConnection.disconnect();
Log.e("RESULT", result);
JSONObject jsonObject = new JSONObject(result);
JSONArray result1 = jsonObject.getJSONArray("result");
for (int i = 0; i < result1.length(); i++) {
JSONObject c = result1.getJSONObject(i);
String id = c.getString("songID");
String names = c.getString("songName");
String ss = c.getString("singerName");
listofsoongs.add(new songsarray(ss,id,names));
}
return jsonObject;
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(JSONObject json) {
pDialog.dismiss();
//EDIT 3: set your adapter here as this method will be called on the UI Thread
itemsAdapter = new MyCustomAdapterSongs(this, listofsoongs);
listView.setAdapter(itemsAdapter);
}
}
}
}
`

code which one should I change to throw button and instantly displays my listview without having to click a button

code which one should I change to throw button and instantly displays my listview without having to click a button
public class MainActivity extends AppCompatActivity {
Button btnLoadFeed; <<<<<------------- Which should I remove associated with this code?
TextView textViewFeedUrl;
ListView listViewFeed;
List<FeedItem> listFeedItems;
ListAdapter adapterFeed;
String myFeed = "http://temfilm.blogspot.co.id/feeds/posts/default?alt=json";
//String myFeed = "http://arduino-er.blogspot.com/feeds/posts/default?alt=json";
//String myFeed = "http://helloraspberrypi.blogspot.com/feeds/posts/default?alt=json";
//String myFeed = "http://photo-er.blogspot.com/feeds/posts/default?alt=json";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btnLoadFeed = (Button)findViewById(R.id.loadfeed);
textViewFeedUrl = (TextView)findViewById(R.id.feedurl);
setContentView(R.layout.layout_feed);
listViewFeed = (ListView)findViewById(R.id.listviewfeed);
listFeedItems = new ArrayList<>();
adapterFeed = new ArrayAdapter<FeedItem>(
this, android.R.layout.simple_list_item_1, listFeedItems);
listViewFeed.setAdapter(adapterFeed);
btnLoadFeed.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
textViewFeedUrl.setText(myFeed);
new JsonTask(listFeedItems, listViewFeed).execute(myFeed);
}
});
}
/*
JsonTask:
AsyncTask to download and parse JSON Feed of blogspot in background
*/
private class JsonTask extends AsyncTask<String, FeedItem, String> {
List<FeedItem> jsonTaskList;
ListView jsonTaskListView;
public JsonTask(List<FeedItem> targetList, ListView targetListView) {
super();
jsonTaskList = targetList;
jsonTaskListView = targetListView;
}
#Override
protected void onPreExecute() {
super.onPreExecute();
jsonTaskList.clear();
jsonTaskListView.invalidateViews();
}
#Override
protected String doInBackground(String... params) {
try {
final String queryResult = sendQuery(params[0]);
parseQueryResult(queryResult);
} catch (IOException e) {
e.printStackTrace();
final String eString = e.toString();
runOnUiThread(new Runnable() {
#Override
public void run() {
Toast.makeText(MainActivity.this,
eString,
Toast.LENGTH_LONG).show();
}
});
} catch (JSONException e) {
e.printStackTrace();
final String eString = e.toString();
runOnUiThread(new Runnable() {
#Override
public void run() {
Toast.makeText(MainActivity.this,
eString,
Toast.LENGTH_LONG).show();
}
});
}
return null;
}
#Override
protected void onProgressUpdate(FeedItem... values) {
FeedItem newItem = values[0];
jsonTaskList.add(newItem);
jsonTaskListView.invalidateViews();
}
private String sendQuery(String query) throws IOException {
String queryReturn = "";
URL queryURL = new URL(query);
HttpURLConnection httpURLConnection = (HttpURLConnection)queryURL.openConnection();
if(httpURLConnection.getResponseCode() == HttpURLConnection.HTTP_OK){
InputStreamReader inputStreamReader =
new InputStreamReader(httpURLConnection.getInputStream());
BufferedReader bufferedReader = new BufferedReader(
inputStreamReader, 8192);
String line = null;
while((line = bufferedReader.readLine()) != null){
queryReturn += line;
}
bufferedReader.close();
}
return queryReturn;
}
private void parseQueryResult(String json) throws JSONException {
JSONObject jsonObject = new JSONObject(json);
final JSONObject jsonObject_feed = jsonObject.getJSONObject("feed");
final JSONArray jsonArray_entry = jsonObject_feed.getJSONArray("entry");
runOnUiThread(new Runnable() {
#Override
public void run() {
if(jsonArray_entry == null){
Toast.makeText(MainActivity.this,
"jsonArray_entry == null",
Toast.LENGTH_LONG).show();
}else{
Toast.makeText(MainActivity.this,
String.valueOf(jsonArray_entry.length()),
Toast.LENGTH_LONG).show();
for(int i=0; i<jsonArray_entry.length(); i++){
try {
JSONObject thisEntry = (JSONObject) jsonArray_entry.get(i);
JSONObject thisEntryTitle = thisEntry.getJSONObject("title");
String thisEntryTitleString = thisEntryTitle.getString("$t");
JSONArray jsonArray_EntryLink = thisEntry.getJSONArray("link");
//search for the link element with rel="alternate"
//I assume it's one and only one element with rel="alternate",
//and its href hold the link to the page
for(int j=0; j<jsonArray_EntryLink.length(); j++){
JSONObject thisLink = (JSONObject) jsonArray_EntryLink.get(j);
try{
String thisLinkRel = thisLink.getString("rel");
if(thisLinkRel.equals("alternate")){
try{
String thisLinkHref = thisLink.getString("href");
FeedItem thisElement = new FeedItem(
thisEntryTitleString.toString(),
thisLinkHref);
publishProgress(thisElement);
break;
}catch (JSONException e){
//no such mapping exists
}
}
}catch (JSONException e){
//no such mapping exists
}
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
}
});
}
}
}

I having been getting the error "no value for url"

This is my java code. I have been getting no value for url in my android studio. I intend to get image from sql database at wamp server.
public class MainActivity extends AppCompatActivity implements
View.OnClickListener{
private String imagesJSON;
private static final String JSON_ARRAY ="result";
private static final String IMAGE_URL = "url";
private JSONArray arrayImages= null;
private int TRACK = 0;
private static final String IMAGES_URL =
"http://192.168.43.214/apexStore2/image.php";
private Button buttonFetchImages;
private Button buttonMoveNext;
private Button buttonMovePrevious;
private ImageView imageView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
imageView = (ImageView) findViewById(R.id.imageView);
buttonFetchImages = (Button) findViewById(R.id.buttonFetchImages);
buttonMoveNext = (Button) findViewById(R.id.buttonNext);
buttonMovePrevious = (Button) findViewById(R.id.buttonPrev);
buttonFetchImages.setOnClickListener(this);
buttonMoveNext.setOnClickListener(this);
buttonMovePrevious.setOnClickListener(this);
}
private void extractJSON(){
try {
JSONObject jsonObject = new JSONObject(imagesJSON);
arrayImages = jsonObject.getJSONArray(JSON_ARRAY);
} catch (JSONException e) {
e.printStackTrace();
}
}
private void showImage(){
try {
JSONObject jsonObject = arrayImages.getJSONObject(TRACK);
getImage(jsonObject.getString(IMAGE_URL));
} catch (JSONException e) {
e.printStackTrace();
}
}
private void moveNext(){
if(TRACK < arrayImages.length()){
TRACK++;
showImage();
}
}
private void movePrevious(){
if(TRACK>0){
TRACK--;
showImage();
}
}
private void getAllImages() {
class GetAllImages extends AsyncTask<String,Void,String>{
ProgressDialog loading;
#Override
protected void onPreExecute() {
super.onPreExecute();
loading = ProgressDialog.show(MainActivity.this, "Fetching
Data...","Please Wait...",true,true);
}
#Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
loading.dismiss();
imagesJSON = s;
extractJSON();
showImage();
}
#Override
protected String doInBackground(String... params) {
String uri = params[0];
BufferedReader bufferedReader = null;
try {
URL url = new URL(uri);
HttpURLConnection con = (HttpURLConnection)
url.openConnection();
con.setRequestProperty("Content-Type",
"application/json;charset=utf-8");
con.setRequestProperty("X-Requested-With",
"XMLHttpRequest");
StringBuilder sb = new StringBuilder();
bufferedReader = new BufferedReader(new
InputStreamReader(con.getInputStream()));
String json;
while((json = bufferedReader.readLine())!= null){
sb.append(json+"\n");
}
return sb.toString().trim();
}catch(Exception e){
return null;
}
}
}
GetAllImages gai = new GetAllImages();
gai.execute(IMAGES_URL);
}
private void getImage(String urlToImage){
class GetImage extends AsyncTask<String,Void,Bitmap>{
ProgressDialog loading;
#Override
protected Bitmap doInBackground(String... params) {
URL url = null;
Bitmap image = null;
String urlToImage = params[4];
try {
url = new URL(urlToImage);
image =
BitmapFactory.decodeStream(url.openConnection().getInputStream());
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return image;
}
#Override
protected void onPreExecute() {
super.onPreExecute();
loading = ProgressDialog.show(MainActivity.this,"Downloading
Image...","Please wait...",true,true);
}
#Override
protected void onPostExecute(Bitmap bitmap) {
super.onPostExecute(bitmap);
loading.dismiss();
imageView.setImageBitmap(bitmap);
}
}
GetImage gi = new GetImage();
gi.execute(urlToImage);
}
#Override
public void onClick(View v) {
if(v == buttonFetchImages) {
getAllImages();
}
if(v == buttonMoveNext){
moveNext();
}
if(v== buttonMovePrevious){
movePrevious();
}
}
This is my php code. When i run my php code, i got the following output:
{
"result": [{
"product_img1": "product-131.jpg"
}, {
"product_img1": "product-124.jpg"
}, {
"product_img1": "product-118.jpg"
}, {
"product_img1": "product-126.jpg"
}, {
"product_img1": "USM_New_Logo1.jpg"
}, {
"product_img1": "UI.PNG"
}, {
"product_img1": "cat402.PNG"
}, {
"product_img1": "launcher.png"
}]
}
My php code got fetch the image from sql database, however, my android studio could not fetch it. Is there any solutions to it?
<?php
include ('classes/functions.php');
$check_product = "SELECT * FROM products WHERE cat_id = '0';";
$run_product_checking = mysqli_query($con, $check_product);
$result = array();
while($row = mysqli_fetch_array($run_product_checking)){
array_push($result,
array('product_img1'=>$row[4]
));
}
echo json_encode(array("result"=>$result));
?>

Change the IP-address into it's Domain-name value.

According to your AsyncTask class, you are passing the url as the first parameter,
class GetImage extends AsyncTask<String,Void,Bitmap>{
.....
}
But here you are receiving it as the 4'th parameter,
String urlToImage = params[4];
To solve this, simply replace the param value from 4 to 0,
String urlToImage = params[0];
PS: Make sure the JSON string " IMAGE_URL " doesn't returns null value,
getImage(jsonObject.getString(IMAGE_URL));