I have a problem to show my array list items on screen. googled every possible error but nothing helped. because those answers was for lower API 23. this is my whole code,so pleasse help me,what should i do?
MainActivity
package com.example.earthquake6;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
//import android.support.v7.app.AppCompatActivity;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;
import java.util.ArrayList;
import java.util.List;
//import android.app.LoaderManager;//OK
//import androidx.loader.app.LoaderManager;
import android.content.Loader;//Ok
//import androidx.loader.content.Loader;
import android.app.LoaderManager.LoaderCallbacks;//OK
//import androidx.loader.app.LoaderManager.LoaderCallbacks;
public class MainActivity extends AppCompatActivity implements LoaderCallbacks<List<CustomWord>> {
// @@@@@@@@@@ States
//region
private static final String LOG_TAG = MainActivity.class.getName();
/**
* URL for earthquake data from the USGS dataset
*/
private static final String USGS_REQUEST_URL =
"http://earthquake.usgs.gov/fdsnws/event/1/query?format=geojson&orderby=time&minmag=6&limit=10";
/**
* Constant value for the earthquake loader ID. We can choose any integer.
* This really only comes into play if you're using multiple loaders.
*/
private static final int EARTHQUAKE_LOADER_ID = 1;
/**
* Adapter for the list of earthquakes
*/
private CustomArrayAdapter mCustomArrayAdapter;
//endregion
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.i("*********************", "*********************");
Log.i(LOG_TAG, "Test: EarthQuacke Activity onCreate called");
setContentView(R.layout.share_activity);
// Create a new adapter that takes an empty list of earthquakes as input
mCustomArrayAdapter = new CustomArrayAdapter(MainActivity.this, new ArrayList<CustomWord>());
// Create list view to set our customArrayAdapter on it
ListView listView = (ListView) findViewById(R.id.share_view_id);
listView.setAdapter(mCustomArrayAdapter);
// to set OnclickListener on each roe of listviews
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
// get rows of each elements in listview
// each row is a "CustomWord.class", so when get elemnts from
// a listview by below
CustomWord customWord1 = mCustomArrayAdapter.getItem(position);
// now get url elemnt
// uri use to convert ulr string to a legal encoding format and acceptable to ulr object
// To make these characters legal they need to be encoded before passing them to the URL constructor.
Uri uri = Uri.parse(customWord1.getmUrl());
// define an intent to open related website
// for send an intent to another app use Intent.ACTION_VIEW
// for more inf
// https://developer.android.com/training/basics/intents/sending
Intent urlIntent = new Intent(Intent.ACTION_VIEW, uri);
startActivity(urlIntent);
}
});
// Get a reference to the LoaderManager, in order to interact with loaders.
// LoaderManager loaderManager = getLoaderManager();
android.app.LoaderManager loaderManager1 = getLoaderManager();
// Initialize the loader. Pass in the int ID constant defined above and pass in null for
// the bundle. Pass in this activity for the LoaderCallbacks parameter (which is valid
// because this activity implements the LoaderCallbacks interface).
//The third argument(here: this) is what object should receive the LoaderCallbacks (and therefore,
// the data when the load is complete!) - which will be this activity. This code goes
// inside the onCreate() method of the EarthquakeActivity, so that the loader
// can be initialized as soon as the app opens.
loaderManager1.initLoader(EARTHQUAKE_LOADER_ID, null, this);
Log.i(LOG_TAG, "Test: EarthQuacke Activity LoaderManager.initLoader called");
}
@Override
public Loader<List<CustomWord>> onCreateLoader(int id, Bundle args) {
// Create a new loader for the given URL
Log.i(LOG_TAG,"Test: EarthQuacke Activity onCreateLoader called");
return new EarthQuakeLoader(this,USGS_REQUEST_URL);
}
@Override
public void onLoadFinished(Loader<List<CustomWord>> loader, List<CustomWord> customWordList) {
// Clear the adapter of previous earthquake data
Log.i(LOG_TAG,"Test: EarthQuacke Activity onLoadFinished called");
mCustomArrayAdapter.clear();
// If there is a valid list of {@link Earthquake}s, then add them to the adapter's
// data set. This will trigger the ListView to update.
if (customWordList != null && !customWordList.isEmpty()) {
mCustomArrayAdapter.addAll(customWordList);
}
}
@Override
public void onLoaderReset(Loader<List<CustomWord>> loader) {
Log.i(LOG_TAG,"Test: EarthQuacke Activity onLoaderReset called");
// Loader reset, so we can clear out our existing data.
mCustomArrayAdapter.clear();
}
}
Then
In my Loader : EarthQuakeLoader
package com.example.earthquake6;
//import androidx.loader.content.AsyncTaskLoader; -----
//import android.content.AsyncTaskLoader;++++
import android.content.AsyncTaskLoader;//Ok
//import androidx.loader.content.AsyncTaskLoader;//xxxxxxxxxxxxxxxxxx
import android.content.Context;
import androidx.core.content.ContextCompat;
import android.util.Log;
// we should use import android.content.AsyncTaskLoader; or import androidx.loader.content.AsyncTaskLoader;
// rather than import androidx.loader.content.AsyncTaskLoader;
// because if we do not use import android.content.AsyncTaskLoader;, we got error on MainActivity class
// at the code related to:
//@Override
//public Loader<List<CustomWord>> onCreateLoader(int id, Bundle args) {
// // Create a new loader for the given URL
// return new EarthQuakeLoader(this,USGS_REQUEST_URL);
// }
// this library is This class was deprecated in API level 28. by android developer ref:
// https://developer.android.com/reference/android/content/AsyncTaskLoader
//we could Use the : Support Library AsyncTaskLoader
import java.util.List;
public class EarthQuakeLoader extends AsyncTaskLoader<List<CustomWord>> {
// @@@@@@@@@@ States
//region
/** Tag for log messages */
private static final String LOG_TAG = EarthQuakeLoader.class.getName();
/** Query URL */
private String mUrl;
//endregion
/**
* Constructs a new {@link EarthQuakeLoader}.
*
* @param context of the activity
* @param url to load data from
*/
public EarthQuakeLoader(Context context, String url) {
super(context);
mUrl = url;
}
@Override
protected void onStartLoading() {
Log.i(LOG_TAG,"Test: EarthQuakeLoader Class onStartLoading called");
forceLoad();
}
@Override
public List<CustomWord> loadInBackground() {
if(mUrl!=null){
return null;
}
// Perform the network request, parse the response, and extract a list of earthquakes.
List<CustomWord> customWordList = FetchDataFromInternet.customArrayListFetchDataFromInternet(mUrl);
Log.i(LOG_TAG,"Test: EarthQuakeLoader Class loadInBackground called");
return customWordList;
}
@Override
public void deliverResult(List<CustomWord> data) {
Log.i(LOG_TAG,"Test: EarthQuakeLoader Class deliverResult called");
super.deliverResult(data);
}
}
and in another classes:
CustomWord :
package com.example.earthquake6;
public class CustomWord {
// States
private double mMagnitude;
private String mPlace;
private long mTime;
private String mUrl;
// Constructor
public CustomWord(double magnitude,String place,long time,String url){
this.mMagnitude = magnitude;
this.mPlace = place;
this.mTime = time;
this.mUrl = url;
}
public double getmMagnitude() {
return mMagnitude;
}
public String getmPlace() {
return mPlace;
}
public long getmTime() {
return mTime;
}
public String getmUrl() {
return mUrl;
}
}
and another class:
FetchDataFromInternet :
package com.example.earthquake6;
import android.text.TextUtils;
import android.util.Log;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.URL;
import java.nio.charset.Charset;
import java.util.ArrayList;
/**
* Helper methods related to requesting and receiving earthquake data from USGS.
*/
public final class FetchDataFromInternet {
// AsyncTask<Params,Progress,Result > :
// if one elemnt do not use, then we use "Void" replace with it
// in this app we use: AsyncTask<URL, Void, String>,becuase we dont use progress
//
// any element in this < , , >, is an object, even its be a primitive data type like int,long,
// or else. so long changed to Long, either void change to Void with capital v
// as there are multiple variable for Params(so saved in array), There are multiple variable
// for Progress(so saved in array),ans either for Result(so saved in array)
// Params :
// its method to use is : doInBackground
// data type in parameters sent to background task, here data type is URL,that means that background
// in doInBackground(URL... urls) task will accept the list of URLs
// Progress :
// its method to use is : onProgressUpdate
// data type used for, measuring progress of the work being down on the
// background thread,to do this, we specify Progress as "Integer" data type,as
// progress parameter,so we can call "publish prgress with integer value in the background,
// then in method,"onProgressUpdate(Integer progress)", which is called by main thread, we
// receive that integer progress and update UI
// Result :
// its method to use is : onPostExecute
// is data type of return value from "doInBackground" method
// this is data type of result of background work
// in this app, return data type from "doInBackground" method is string,so we have String data type in
// AsyncTask<URL, Void, String>
// @@@@@@@@@@ States
//region
// use to set up log messages
public static final String LOG_TAG = FetchDataFromInternet.class.getSimpleName();
//endregion
// Constructor
//region
/**
* Create a private constructor because no one should ever create a {@link FetchDataFromInternet} object.
* This class is only meant to hold static variables and methods, which can be accessed
* directly from the class name QueryUtils (and an object instance of QueryUtils is not needed).
*/
private FetchDataFromInternet() {
}
//endregion
public static ArrayList<CustomWord> customArrayListFetchDataFromInternet(String stringURL) {
// Step 1: Create Url object from nput string url
Log.i(LOG_TAG,"Test: FetchDataFromInternet Class customArrayListFetchDataFromInternet called");
// Don't perform the request if there are no URLs, or the first URL is null.
if (stringURL == null) {
return null;
}
URL urlObject = creatURL(stringURL);
/* // Perform HTTP request to the URL and receive a JSON response back
// 2- Obtain a URLConnection object from the URL
// 3- Configure the URLConnection
// 4- Read the header fields :::: Not used Here
// 5- Get an input stream and read data
// steps above are in below method*/
String jasonStringUrlSourceResponse = "";//set to null
try{
// if jasonStringUrlSourceResponse url is null then jasonStringUrlSourceResponse is null
jasonStringUrlSourceResponse = httpConectionReadStreamedData(urlObject);// if httpConectionReadStreamedData method,
// has no throw exception,this try/catch got error
}catch (IOException ioException){
// handler
Log.e(LOG_TAG, "Problem making the HTTP request.", ioException);
}
// Extract relevant fields from the JSON response and create an {@link Event} object
ArrayList arrayListQueryFromJAson = QueryFromJAson(jasonStringUrlSourceResponse);
return arrayListQueryFromJAson;
}
/////////////////////// 1- Create URL object from given String
private static URL creatURL(String urlString) {
URL myURL = null;
try {
// prepare url for creating a URL object,because url maybe has special characters example:
// http://example.com/hello world/ -------URI-----> http://example.com/hello%20world
// the space between hello and world occupy by %20 automatically by uri
// this do by
URI uri = new URI(urlString);
// Convert uri to url
myURL = uri.toURL();
} catch (MalformedURLException | URISyntaxException exception) { //MalformedURLException is for URL URISyntaxException exception is for URI
Log.v("LOG_TAG","Error with creating URL",exception);
exception.printStackTrace();
return null;
}
return myURL;// URL myURL = null; must be declared for return
}// End creatURL
private static String httpConectionReadStreamedData(URL myURL) throws IOException{// need throws ioexception
String jsonResponse = "";
// to make sure that url is not null
if(myURL==null){
return jsonResponse;// by return jsonResponse we get out the method httpConectionReadStreamedData
}
HttpURLConnection urlConnection = null;
InputStream inputStream = null;
try {
// 2- Obtain a URLConnection object from the URL
// A URLConnection instance is obtained by invoking the openConnection() method on the URL object:
// URLConnection urlCon = url.openConnection();
// If the protocol is http://, you can cast the returned object to an HttpURLConnection object:
HttpURLConnection httpURLConnection = (HttpURLConnection) myURL.openConnection();
// 3- Configure the URLConnection
httpURLConnection.setRequestMethod("GET");
// Timeout for reading InputStream arbitrarily set to 10000 mili second
httpURLConnection.setReadTimeout(10000 /* milliseconds */);
// Timeout for connection.connect() arbitrarily set to 15000 ms
httpURLConnection.setConnectTimeout(15000 /* milliseconds */);
// Open communications link (network traffic occurs here).
httpURLConnection.connect();
// After the connection has been established, then its need to check the response code by
// calling below code
// if the request " httpURLConnection.connect();" is successful (response code is 200)
// so we could do 4 & 5 steps(read the input stream and then parse the response
if(httpURLConnection.getResponseCode()==200){
// 4- Read the header fields :::: Not used Here
// 5- Get an input stream and read data
inputStream = httpURLConnection.getInputStream();
// The InputStream’s read() is a low-level method that reads data to an array of bytes.
// So it is more convenient to wrap the InputStream in an InputStreamReader for reading data to characters;
// Here we use readFromStream method to read data
//An InputStream is a readable source of bytes. Once you get an InputStream, it's common
// to decode or convert it into a target data type. For example, if you were downloading
// image data, you might decode and display it
jsonResponse = readFromInputStream(inputStream);// maybe "inputStream", be null becuase "httpURLConnection" method maybe
// return null string, so need to check handling null string url in the method
}else{
Log.e(LOG_TAG,"Error response code: "+urlConnection.getResponseCode());
}
} catch (IOException e) {
Log.e(LOG_TAG,"Problem to making HttpURLConnection httpURLConnection = " +
"(HttpURLConnection) myURL.openConnection();",e);
// e.printStackTrace();
}finally {
if (inputStream != null) {//// Close Stream and disconnect HTTPS connection.
// function must handle java.io.IOException here
inputStream.close();
}
if (urlConnection != null) {
urlConnection.disconnect();
}
}
return jsonResponse;
}// End httpConectionReadStreamedData method
// After read data from url(streamming data), its need to form data to readable String data
// The InputStream’s read() is a low-level method that reads stream data to an array of bytes.
//An InputStream is a readable source of bytes. Once you get an InputStream, it's common
// to decode or convert it into a target data type. For example, if you were downloading
// image data, you might decode and display it
private static String readFromInputStream(InputStream inputStream) throws IOException {// this exception is due to bufferedReader.readLine();
StringBuilder stringBuilder = new StringBuilder();// to concatinate streams of char data
if(inputStream!=null){
// for read streams of byte char data from inputstream url
InputStreamReader inputStreamReader = new InputStreamReader(inputStream, Charset.forName("UTF-8"));
// To increase performance. Data to be read will be buffered in to memory for quick access
// for more info : http://www.javalearningacademy.com/streams-in-java-concepts-and-usage/
BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
String line = bufferedReader.readLine();// read data from buffer
while(line!=null){ // while there is data, line of data appent to each other
stringBuilder.append(line);
line = bufferedReader.readLine();
}
}
return stringBuilder.toString();
}
/**
* Return an {@link CustomWord} object by parsing out information
* about the first earthquake from the input earthquakeJSON string.
*/
private static ArrayList QueryFromJAson(String jasonInputString){
// final ArrayList<CustomWord> customArrayList = nnull;
// if we define line below as above we get error
final ArrayList<CustomWord> customArrayList = new ArrayList<>();
// If the JSON string is empty or null, then return early.
if (TextUtils.isEmpty(jasonInputString)) {
return null;
}
// use try/catch to pass out from class if there is a error
try {
JSONObject root = new JSONObject(jasonInputString);
// Get "features" path to get next path and route to place,time,magnitude,...,etc
JSONArray root_features = root.getJSONArray("features");
// Create Custom list array to add "mag,place,time,url
for (int root_features_Elements_counter=0;root_features_Elements_counter<root_features.length();
root_features_Elements_counter++){
JSONObject root_features_Elements = root_features.getJSONObject(root_features_Elements_counter);
JSONObject root_features_Elements_properties = root_features_Elements.getJSONObject("properties");
double magnitude = root_features_Elements_properties.getDouble("mag");
String place = root_features_Elements_properties.getString("place");
long time = root_features_Elements_properties.getLong("time");
String url = root_features_Elements_properties.getString("url");
// Add "mag,place,time,url to CustomArrayList
customArrayList.add(new CustomWord(magnitude,place,time,url));
}//End for
} catch (JSONException e) {
e.printStackTrace();
Log.e(LOG_TAG, "Problem parsing the earthquake JSON results", e);
}
return customArrayList;
}
}// End Class FetchDataFromInteret
and another:
QueryFromJAson :
package com.example.earthquake6;
import android.util.Log;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import static com.example.earthquake6.FetchDataFromInternet.LOG_TAG;
//import static com.example.earthquakerev4_staticclass.MainActivity.LOG_TAG;
public class QueryFromJAson {
// States
private ArrayList<CustomWord> customArrayList = new ArrayList<>();
// Constructor
public QueryFromJAson(String jasonInputString){
/* // If the JSON string is empty or null, then return early.
if (TextUtils.isEmpty(jasonInputString)) {
return null;
}*/
// use try/catch to pass out from class if there is a error
try {
JSONObject root = new JSONObject(jasonInputString);
// Get "features" path to get next path and route to place,time,magnitude,...,etc
JSONArray root_features = root.getJSONArray("features");
// Create Custom list array to add "mag,place,time,url
for (int root_features_Elements_counter=0;root_features_Elements_counter<root_features.length();
root_features_Elements_counter++){
JSONObject root_features_Elements = root_features.getJSONObject(root_features_Elements_counter);
JSONObject root_features_Elements_properties = root_features_Elements.getJSONObject("properties");
double magnitude = root_features_Elements_properties.getDouble("mag");
String place = root_features_Elements_properties.getString("place");
long time = root_features_Elements_properties.getLong("time");
String url = root_features_Elements_properties.getString("url");
// Add "mag,place,time,url to CustomArrayList
customArrayList.add(new CustomWord(magnitude,place,time,url));
}//End for
} catch (JSONException e) {
e.printStackTrace();
Log.e(LOG_TAG, "Problem parsing the earthquake JSON results", e);
}
}// End Constructor
public ArrayList<CustomWord> getCustomArrayList() {
return customArrayList;
}
} // End Class
i prefer to code with lbrary androidx rather than support library like, import android.support.v4. after run this app, screen nothing shows.
