Right now, I am in the process of "optimizing" my app. I am still a beginner, so what I am doing is basically moving methods from my MainActivity.class to their separate class. I believe it's called Encapsulation (Please correct me if I'm wrong).
My application needs to :
Get a YouTube Playlist Link from the YouTube App (with an Intent, android.intent.action.SEND).
Use the link to fetch data from the Google Servers with the YouTubeApi and Volley.
Read the data received and add it to an arrayList<String>.
What my YouTubeUsage.java class is supposed to do, is fetch data with the YouTubeApi and Volley then store the data using SharedPreferences. Once the data is saved, the data is being read in my ConvertActivity.class (It's an activity specifically created for android.intent.action.SEND) with my method getVideoIds() before setting an adapter for my listView in my createRecyclerView() method.
YouTubeUsage.java
public class YoutubeUsage {
private Boolean results = false;
private String mResponse;
private ArrayList<String> videoIds = new ArrayList<>();
String Url;
public String getUrl(String signal) {
String playlistId = signal.substring(signal.indexOf("=") + 1);
this.Url = "https://www.googleapis.com/youtube/v3/playlistItems?part=contentDetails%2C%20snippet%2C%20id&playlistId=" +
playlistId + "&maxResults=25&key=" + "API_KEY";
return this.Url;
}
public void fetch(String Url, final Context context){
RequestQueue queue = Volley.newRequestQueue(context);
StringRequest request = new StringRequest(Request.Method.GET, Url,
new Response.Listener<String>() {
#Override
public void onResponse(String response) {
sharedPreferences(response, context);
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
Log.e("VolleyError", Objects.requireNonNull(error.getMessage()));
}
});
queue.add(request);
}
private void sharedPreferences(String response, Context context){
SharedPreferences m = PreferenceManager.getDefaultSharedPreferences(context);
SharedPreferences.Editor editor = m.edit();
if (m.contains("serverResponse")){
if (!m.getString("serverResponse", "").equals(response)){
editor.remove("serverResponse");
editor.apply();
updateSharedPreferences(response, context);
}
} else{
updateSharedPreferences(response, context);
}
}
private void updateSharedPreferences(String mResponse, Context mContext){
SharedPreferences m = PreferenceManager.getDefaultSharedPreferences(mContext);
SharedPreferences.Editor editor = m.edit();
editor.putString("serverResponse", mResponse);
editor.apply();
}
}
ConvertActivity.java
public class ConvertActivity extends AppCompatActivity {
YoutubeUsage youtubeUsage = new YoutubeUsage();
ArrayList<String> videoIDs = new ArrayList<>();
String Url = "";
ListView listView;
MyCustomAdapter myCustomAdapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_convert);
listView = findViewById(R.id.listview_convert);
Intent intent = getIntent();
String action = intent.getAction();
String type = intent.getType();
if ("android.intent.action.SEND".equals(action) && "text/plain".equals(type)) {
Url = youtubeUsage.getUrl(Objects.requireNonNull(intent.getStringExtra("android.intent.extra.TEXT")));
}
//I would like to avoid the try/catch below
try {
videoIDs = getVideoIDs(Url, this);
createRecyclerView(videoIDs);
Log.i("ResponseVideoIDs", String.valueOf(videoIDs.size()));
} catch (JSONException e) {
e.printStackTrace();
}
}
private ArrayList<String> getVideoIDs(String Url, Context context) throws JSONException {
ArrayList<String> rawVideoIDs = new ArrayList<>();
youtubeUsage.fetch(Url, context);
SharedPreferences m = PreferenceManager.getDefaultSharedPreferences(context);
String serverResponse = m.getString("serverResponse", "");
JSONObject jsonObject = new JSONObject(serverResponse);
JSONArray jsonArray = jsonObject.getJSONArray("items");
for (int i = 0; i<jsonArray.length(); i++){
JSONObject jsonObject1 = jsonArray.getJSONObject(i);
JSONObject jsonVideoId = jsonObject1.getJSONObject("contentDetails");
rawVideoIDs.add(jsonVideoId.getString("videoId"));
}
return rawVideoIDs;
}
private void createRecyclerView(ArrayList<String> videoIDs){
myCustomAdapter = new MyCustomAdapter(this, videoIDs);
listView.setAdapter(myCustomAdapter);
myCustomAdapter.notifyDataSetChanged();
}
}
Everything works fine, however, my sharedPreferences never gets updated. Which means, if I share a YouTube playlist from the YouTube App to my app with 3 items in it, it will work fine. The Listview will show 3 items with their corresponding IDs as it should. But, if I share a YouTube playlist again, my app will still hold on to the data of the previous playlist I shared (even if I close it), showing the item number and the IDs of the previous link. If i continue to share the same playlist over and over, it will eventually show the correct number of items and the correct IDs.
I could totally put all my methods from the YouTubeUsage.java in my ConvertActivity.class preventing me from using SharedPreferences to transfer data between the two java classes. However, JSON throws an exception. That means I have to encapsulate my code with try/catch. I would like to avoid those since I need to do a lot of operations on the data just received by Volley (check a class size, look for certains strings). I find that doing this in these try/catch don't work like I want. (i.e. outside the try/catch, the values remains the same even if I updated them in the try/catch).
I want to know two things.
How can I correct this problem?
Is this the most efficient way to do this (optimization)? (I though of maybe
converting the VolleyResponse to a string with Gson then store the String file, but I don't know if that's the best way to do it since it's supposed to be
provisional data. It feels like just more of the same).
Thank You!
There is an issue with making assumptions about order of events. Volley will handle requests asynchronously, so it is advisable to implement the observer pattern here.
Create a new Java file that just contains:
interface MyNetworkResponse {
void goodResponse(String responseString);
}
Then make sure ConvertActivity implements MyNetworkResponse and create method:
void goodResponse(String responseString) {
// handle a positive response here, i.e. extract the JSON and send to your RecyclerView.
}
within your Activity.
In your YoutubeUsage constructor, pass in the Activity context (YoutubeUsage) and then store this in a YoutubeUsage instance variable called ctx.
In onCreate, create an instance of YoutubeUsage and pass in this.
In onResponse just call ctx.goodResponse(response).
Amend the following block to:
if ("android.intent.action.SEND".equals(action) && "text/plain".equals(type)) {
Url = youtubeUsage.getUrl(Objects.requireNonNull(intent.getStringExtra("android.intent.extra.TEXT")));
youtubeUsage.fetch(Url);
}
Delete the try/catch from onCreate.
And no need to use SharedPreferences at all.
UPDATE
Try this code:
MyNetworkResponse.java
interface MyNetworkResponse {
void goodResponse(String responseString);
void badResponse(VolleyError error);
}
YoutubeUsage.java
class YoutubeUsage {
private RequestQueue queue;
private MyNetworkResponse callback;
YoutubeUsage(Object caller) {
this.callback = (MyNetworkResponse) caller;
queue = Volley.newRequestQueue((Context) caller);
}
static String getUrl(String signal) {
String playlistId = signal.substring(signal.indexOf("=") + 1);
return "https://www.googleapis.com/youtube/v3/playlistItems?part=contentDetails%2C%20snippet%2C%20id&playlistId=" + playlistId + "&maxResults=25&key=" + "API_KEY";
}
void fetch(String url){
StringRequest request = new StringRequest(Request.Method.GET, url,
new Response.Listener<String>() {
#Override
public void onResponse(String response) {
callback.goodResponse(response);
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
callback.badResponse(error);
}
});
queue.add(request);
}
}
ConvertActivity.java
public class ConvertActivity extends AppCompatActivity implements MyNetworkResponse {
YoutubeUsage youtubeUsage;
ArrayList<String> videoIDs = new ArrayList<>();
ListView listView;
MyCustomAdapter myCustomAdapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_convert);
listView = findViewById(R.id.listview_convert);
youtubeUsage = new YoutubeUsage(this);
Intent intent = getIntent();
String action = intent.getAction();
String type = intent.getType();
if ("android.intent.action.SEND".equals(action) && "text/plain".equals(type)) {
String url = YoutubeUsage.getUrl(Objects.requireNonNull(intent.getStringExtra("android.intent.extra.TEXT")));
youtubeUsage.fetch(url);
}
}
private ArrayList<String> getVideoIDs(String serverResponse) throws JSONException {
ArrayList<String> rawVideoIDs = new ArrayList<>();
JSONObject jsonObject = new JSONObject(serverResponse);
JSONArray jsonArray = jsonObject.getJSONArray("items");
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject jsonObject1 = jsonArray.getJSONObject(i);
JSONObject jsonVideoId = jsonObject1.getJSONObject("contentDetails");
rawVideoIDs.add(jsonVideoId.getString("videoId"));
}
return rawVideoIDs;
}
private void createRecyclerView(ArrayList<String> videoIDs) {
myCustomAdapter = new MyCustomAdapter(this, videoIDs);
listView.setAdapter(myCustomAdapter);
myCustomAdapter.notifyDataSetChanged();
}
#Override
public void goodResponse(String responseString) {
Log.d("Convert:goodResp", "[" + responseString + "]");
try {
ArrayList<String> rawVideoIDs = getVideoIDs(responseString);
createRecyclerView(rawVideoIDs);
} catch (JSONException e) {
// handle JSONException, e.g. malformed response from server.
}
}
#Override
public void badResponse(VolleyError error) {
// handle unwanted server response.
}
}
Good Day I am completely new to coding. I am building an app which uses a combobox besides other library items. The problem I am facing is that while attempting to populate combobox items from a Mysql Db the item values get duplicated each time the drop down is clicked.
How I can keep this from happening ? I do understand that my approach itself could be erroneous.
#FXML
public void getStation() {
String sqlStationName = " select * from station ";
try {
conn = (Connection) DBConnection.connect();
PreparedStatement pstStn = conn.prepareStatement(sqlStationName);
ResultSet stnRS = pstStn.executeQuery(sqlStationName);
while (stnRS.next()) {
comboBoxStation.getItems().add(stnRS.getString("stationName"));
}
stnRS.close();
pstStn.close();
conn.close();
} catch (SQLException ex) {
System.err.println("ERR" + ex);
}
}
Ok so I moved the function to the initialize() method in the controller and created an Observabale list called station
private ObservableList<String> stationsList = FXCollections.observableArrayList();
#Override
public void initialize(URL url, ResourceBundle rb) {
//
String sqlStationName = " select * from station ";
try {
conn = (Connection) DBConnection.connect();
PreparedStatement pstStn = conn.prepareStatement(sqlStationName);
ResultSet stnRS = pstStn.executeQuery(sqlStationName);
while (stnRS.next()) {
stationsList.add(stnRS.getString("stationName"));
}
stnRS.close();
pstStn.close();
conn.close();
} catch (SQLException ex) {
System.err.println("ERR" + ex);
}
}
and then left only this line in the original function....seems to be working.
#FXML
private void getStation() {
comboBoxStation.setItems(stationsList);
}
I have tried a lot but not able to populate all values in the data base into my combo box table cell.
Controller.java
public class controller {
GetConnection gc = new GetConnection();
PreparedStatement pst;
ResultSet rs;
Statement st;
private ObservableList<Users> datas = FXCollections.observableArrayList();
public controller() {
}
#FXML
private TableView<Users> table;
#FXML
private TableColumn<Users, String> c1;
#FXML
private void editable() {
List<String> names = new ArrayList<String>();
try {
ObservableList<Users> datas = FXCollections.observableArrayList();
String sql = "select * from itemsadd";
pst = gc.getConnection().prepareStatement(sql);
rs = pst.executeQuery();
while (rs.next()) {
String name = rs.getString("itemcode");
names.add(name);
System.out.println("probs" + names);
}
ResultSet rs2 = gc.getConnection().createStatement()
.executeQuery("SELECT * FROM itemsadd WHERE itemcode=1001");
while (rs2.next()) {
datas.add(new Users(rs2.getString("itemcode")));
}
for (String name : names) {
c1.setCellValueFactory(new PropertyValueFactory("Itemc"));
c1.setCellFactory(ComboBoxTableCell.forTableColumn(name));
//not getting full items here
System.out.println("hell3" + name);// am getting full items here
}
table.setItems(null);
table.setItems(datas);
} catch (Exception e) {
e.printStackTrace();
System.out.println("Error on Building Data");
}
}
public static class Users {
private StringProperty Itemc;
private Users(String Itemc) {
this.Itemc = new SimpleStringProperty(Itemc);
}
public String getItemc() {
return Itemc.get();
}
public void setItemc(String Itemc) {
this.Itemc.set(Itemc);
}
public StringProperty ItemcProperty() {
return Itemc;
}
}
}
table.fxml
<?import java.lang.*?>
<?import java.util.*?>
<?import javafx.scene.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>
<AnchorPane id="AnchorPane" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="javafxapplication47.controller">
<children>
<TableView fx:id="table" editable="true" layoutX="136.0" layoutY="58.0" onKeyPressed="#editable" prefHeight="200.0" prefWidth="335.0">
<columns>
<TableColumn fx:id="c1" prefWidth="333.0" text="Name" />
</columns>
</TableView>
</children>
</AnchorPane>
Main.java loader
public class Tableveiw extends Application {
private Stage primaryStage;
private AnchorPane pane;
#Override
public void start(Stage primaryStage) {
this.primaryStage = primaryStage;
this.primaryStage.setTitle("AddressApp");
showPerson();
}
public void showPerson() {
try {
// Load root layout from fxml file.
FXMLLoader loader = new FXMLLoader();
loader.setLocation(Tableveiw.class.getResource("table.fxml"));
pane = (AnchorPane) loader.load();
// Show the scene containing the root layout.
Scene scene = new Scene(pane);
primaryStage.setScene(scene);
primaryStage.show();
} catch (IOException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
launch(args);
}
Database Connection
public class GetConnection {
public Connection getConnection() throws Exception {
Connection con = null;
try {
System.out.println("MySQL Connect Example.");
String url = "jdbc:mysql://localhost:3306/";
String dbName = "login";
String driver = "com.mysql.jdbc.Driver";
// Accessing driver from the jar file
Class.forName(driver).newInstance();
// Creating a veriable for Connection Called conn
con = DriverManager.getConnection(url + dbName, "root", "");
} catch (Exception e) {
e.printStackTrace();
}
return con;
}
public static void main(String arg[]) {
GetConnection con = new GetConnection();
System.out.println("Connection" + con);
}
}
My problem with the code is that am not getting the full items in the database record to my c1 combobox table cell.Am only getting the last items of the database record in my comboboxtablecell.I have created array but still not helping .Why am not able to populate whole items in database into my combobox tablecell .Please help me with neccessary changes in the code.
This is Just basic functionality . when you duble click on cell combobox will visible then you can select value.to see direct Combobox you have write own TableCell class see this you ll understand. I hope this will help you. any ?s post a comment
private void editable() {
try {
ObservableList<String> names = FXCollections.observableArrayList();
ObservableList<Users> datas = FXCollections.observableArrayList();
String sql = "select * from itemsadd";
pst = gc.getConnection().prepareStatement(sql);
rs = pst.executeQuery();
while (rs.next()) {
String name = rs.getString("itemcode");
names.add(name);
System.out.println("probs" + names);
}
ResultSet rs2 = gc.getConnection().createStatement()
.executeQuery("SELECT * FROM itemsadd WHERE itemcode=1001");
while (rs2.next()) {
datas.add(new Users(rs2.getString("itemcode")));
}
c1.setCellValueFactory(new PropertyValueFactory("Itemc"));
c1.setCellFactory(ComboBoxTableCell.forTableColumn(name));
table.setEditable(true);
table.getItems().clear();
table.setItems(datas);
} catch (Exception e) {
e.printStackTrace();
System.out.println("Error on Building Data");
}
I have finally overcome my issue with a NPE in my code whilst learning FX/FXML. I now however have a different problem, a window opens with my TableView however there is no content in the table at all. As you cann I have printed out the JobList to make sure there is content being returned, and this returns three jobs (the correct amount). Am I missing something that binds the table to the returned list?
Here is the code;
public class SecondInterface implements Initializable {
private JobDataAccessor jAccessor;
private String aQuery = "SELECT * FROM progdb.adamJobs";
private Parent layout;
private Connection connection;
#FXML
TableView<Job> tView;
public void newI(Connection connection) throws Exception {
Stage primaryStage;
primaryStage = MainApp.primaryStage;
this.connection = connection;
System.out.println(connection);
FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("Test1.fxml"));
fxmlLoader.setController(this);
try {
layout = (Parent) fxmlLoader.load();
} catch (IOException exception) {
throw new RuntimeException(exception);
}
primaryStage.getScene().setRoot(layout);
}
public Parent getLayout() {
return layout;
}
#Override
public void initialize(URL url, ResourceBundle rb) {
jAccessor = new JobDataAccessor();
try {
System.out.println("This connection: " + connection);
System.out.println("This query: " + aQuery);
List<Job> jList = jAccessor.getJobList(connection, aQuery);
for (Job j : jList) {
System.out.println(j);
}
tView.getItems().addAll(jAccessor.getJobList(connection, aQuery));
} catch (SQLException e) {
e.printStackTrace();
}
}
}
since i am not a java swing expert i need some help to understand why my images in my JList do not appear.
I have a JList that pops up containing all products (with inline pictures) while the user enters a search criteria. The results come from lucene and will be rendered in a JList in real time.
To lazy load the inline product images i am using a swingworker inside my rendering class.
Any help would be great!
public abstract class MatchRenderer implements ListCellRenderer {
#Override
public Component getListCellRendererComponent(JList list, final Object value, int index,
boolean isSelected, boolean cellHasFocus) {
Component component = defaultRenderer.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus);
if (quickRenderMode) {
return component;
} else {
try {
component = renderHook(value, component);
} catch (Exception e) {
System.err.println("Search string: " + searchString);
System.err.println(value.toString());
e.printStackTrace();
}
JPanel itemPanel = new JPanel(new FlowLayout(FlowLayout.LEFT));
JLabel label = new JLabel(defaultIcon, SwingConstants.HORIZONTAL);
itemPanel.add(label);
itemPanel.add(component);
if (value instanceof QoogleEntity && ((QoogleEntity) value).isProduct()) {
QoogleEntity qoogleItem = (QoogleEntity) value;
String imageUrl = qoogleItem.getQInfos().get(0).getqValue();
//LAZY LOAD STARTS HERE...
new ImageRetriever(label, imageUrl).execute();
}
return itemPanel;
}
}
protected abstract Component renderHook(Object value, Component component);
class ImageRetriever extends SwingWorker<ImageIcon, String> {
private JLabel lbImage;
private String imageUrl;
public ImageRetriever(JLabel lbImage, String imageUrl) {
this.lbImage = lbImage;
this.imageUrl = imageUrl;
}
#Override
protected void done() {
try {
lbImage.setIcon(get());
lbImage.repaint();
} catch (Exception e) {
}
}
#Override
protected ImageIcon doInBackground() throws Exception {
return ImageLoader.loadImageFromUrl(imageUrl, 80, 80);
}
};