My CardView duplicate elements upon data change, the vardView is within a tab, and the way i declared that tab fragment as following;
in the onCreateView, i declared all the necessary firebase links and value events listeners to retrieve the required data related to the elements displayed on the cards.
ref.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot snapshot) {
if(snapshot !=null){
for (DataSnapshot child: snapshot.getChildren()) {
Log.i("MyTag", child.getValue().toString());
imagesfeedsList.add(child.child("address").getValue(String.class));
authorfeedsList.add(child.child("author").getValue(String.class));
ratingfeedsList.add(child.child("rating").getValue(String.class));
locationfeedsList.add(child.child("location").getValue(String.class));
publicIDfeedsList.add(child.child("public_id").getValue(String.class));
}
Log.i("MyTag_imagesDirFinal", imagesfeedsList.toString());
mImages = imagesfeedsList.toArray(new String[imagesfeedsList.size()]);
author = authorfeedsList.toArray(new String[authorfeedsList.size()]);
ratingV = ratingfeedsList.toArray(new String[ratingfeedsList.size()]);
locationV = locationfeedsList.toArray(new String[locationfeedsList.size()]);
publicID = publicIDfeedsList.toArray(new String[publicIDfeedsList.size()]);
numbOfAdrs = Long.valueOf(imagesfeedsList.size());
LENGTH = Integer.valueOf(String.valueOf(numbOfAdrs));
}
right after the snippet the adapter setup;
ContentAdapter adapter = new ContentAdapter(recyclerView.getContext());
recyclerView.setAdapter(adapter);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
return recyclerView;
}
Then comes the view holder with a RecycleView, declaring the cardView elements. One of the elements is a ratingBar, and here where the ratingbar Listener is to submit the user rating on a specific picture.
after that the content adapter;
public static class ContentAdapter extends RecyclerView.Adapter<ViewHolder> {
// Set numbers of List in RecyclerView.
private Context mContext;
public ContentAdapter(Context context) {
this.mContext = context;
}
#Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
return new ViewHolder(LayoutInflater.from(parent.getContext()), parent);
}
#Override
public void onBindViewHolder(final ViewHolder holder, int position) {
holder.authorName.setText(author[position]);
holder.ratingValue.setText(ratingV[position]);
holder.locationValue.setText(locationV[position]);
Picasso.with(mContext).load(mImages[position]).into(holder.picture);
#Override
public int getItemCount() {
return LENGTH;
}
}
My problem is whenever the user submits a rating or even when the data related to any of the elements on anycard changes, the view gets duplicated ( i mean by the view, the cards ), a repetition of the cards, with the new data chnages displayed ?
i a not sure what is in my above code structure causing this and how to fix this repetitions, i mean i need the cards to be updated with the new data but not duplicated?
All right, so the problem was that every time the data changes, in the onCreate the imagesFeedList, ratingFeedList, etc does not get rid of the old information stored in it from the initial build, so when the refresh happens triggered by onDataChange, the new information gets added to the previous information, which cause the view to repeat the cards, thus just at the beginning of onDataChange and before storing any information in the several feedLists, it must be cleared;
imagesfeedsList.clear();
authorfeedsList.clear();
ratingfeedsList.clear();
locationfeedsList.clear();
publicIDfeedsList.clear();
and by that i made sure the view does not repeat build up based on old information.
Related
I'm trying to create an app for ordering cakes and bakes.
Therefore I have a list of deserts and a list of bakes in 2 different activities.
At the moment, once you click on a dish, its quantity will raise in 1.
However, if I'm returning to the main Activity, and then again to the desert activity (or bake) then the quantity will initialize to 0, as I initialized each dish.
How can I change the dish qauntity of each view once you click on it, and it will be saved even if I leave the activity?
public class DesertsActivity extends AppCompatActivity {
#Override
protected void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.deserts_activity);
final ArrayList<Dish> dishes = new ArrayList<Dish>();
dishes.add(new Dish("Number Cake",180, R.drawable.cake_number, 0));
dishes.add(new Dish("Ear of Haman", 40, R.drawable.ozen_haman, 0));
dishes.add(new Dish("Alphachores", 35, R.drawable.alphachores, 0));
dishes.add(new Dish("Snow Cookies", 35, R.drawable.snow_cookies, 0));
DishAdapter adapter = new DishAdapter(this, dishes);
final ListView listView = (ListView) findViewById(R.id.deserts_list);
listView.setAdapter(adapter);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> adapterView, View view, int position, long l) {
dishes.set(position, new Dish(dishes.get(position).getDishName(),
dishes.get(position).getDishPrice(), dishes.get(position).getDishPic(),
dishes.get(position).getQuantity()+1));
TextView quantity = (TextView) view.findViewById(R.id.quantity);
quantity.setText(String.valueOf(dishes.get(position).getQuantity()));
}
});
}
and here is the adapter
public class DishAdapter extends ArrayAdapter<Dish> {
public DishAdapter(Activity context, ArrayList<Dish> dishes){
super(context, 0, dishes);
}
#NonNull
#Override
public View getView(int position, #Nullable View convertView, #NonNull ViewGroup parent) {
View listItemView = convertView;
if(listItemView == null){
listItemView = LayoutInflater.from(getContext()).inflate(R.layout.list_layout, parent, false);
}
final Dish currenDish = getItem(position);
TextView dishName = (TextView) listItemView.findViewById(R.id.dishName);
dishName.setText(currenDish.getDishName());
TextView dishPrice = (TextView) listItemView.findViewById(R.id.dishPrice);
dishPrice.setText(String.valueOf(currenDish.getDishPrice()));
ImageView image = (ImageView) listItemView.findViewById(R.id.dishPic);
image.setImageResource(currenDish.getDishPic());
image.setVisibility(View.VISIBLE);
TextView quantity = (TextView) listItemView.findViewById(R.id.quantity);
quantity.setText(String.valueOf(currenDish.getQuantity()));
return listItemView;
}
Short-lived storage (system-initiated state dismissal)
To preserve and restore activity's UI state, for example due to the screen rotation, change of language while activity is running, switching into multi-window mode, or any other system-initiated state dismissal you can override onSaveInstanceState(Bundle savedInstanceState) method. Then, once activity is re-created, you can extract this state from Bundle passed to activity's onCreate method.
Saved instance state bundles persist both configuration changes and process death, but are limited by amount of storage and speed because onSavedInstanceState() serializes data to disk. Serialization can consume a lot of memory if the objects being serialized are complicated. Because this process happens on the main thread during a configuration change, serialization can cause dropped frames and visual stutter if it takes too long.
#Override
protected void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.deserts_activity);
if(savedInstanceState != null) {
// restore your data
}
//...
}
Then input Bundle parameter is essentially a Map which takes key-value pairs. Though be aware that there are situations in which this method is not being called. See the docs for onCreate and onSaveInstanceState.
Long-lived storage
To persist a state even after application is closed, consider using databases (SQLite, Realm, etc.), file, or shared preferences.
Persistent local storage, such as a database or shared preferences, will survive for as long as your application is installed on the user’s device (unless the user clears the data for your app). While such local storage survives system-initiated activity and application process death, it can be expensive to retrieve because it will have to be read from local storage in to memory. Often this persistent local storage may already be a part of your application architecture to store all data you don’t want to lose if you open and close the activity.
See Saving UI states
My app is a list of element names. Clicking one goes to another activity with more details, and an editText and button to change its name. When I go back to the list, I want it to have the new name if updated. My onCreate method has this code which populates it from the database perfectly (ignore the hardcoded size, its just simpler for debugging)
final String DATABASE_NAME = "element_db";
final AppDatabase appDatabase;
appDatabase = Room.databaseBuilder(getApplicationContext(), AppDatabase.class, DATABASE_NAME).build();
ListView list = (ListView)findViewById(R.id.listView);
final String[] element = new String[3];
new Thread(new Runnable() {
#Override
public void run() {
List<Element> elements;
elements = appDatabase.elementDao().fetchElements(); // a dao query "select*from"
int size = elements.size();
for (int i = 0; i < size; i++){
element[i] = elements.get(i).getName();
}
}
}) .start();
ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(this, R.layout.activity_list_view, R.id.textView, element);
list.setAdapter(arrayAdapter);
list.setOnItemClickListener(new AdapterView.OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
Intent i = new Intent(MainActivity.this, itemdetail.class);
i.putExtra("pos", position);
startActivity(i);
}
});
To achieve an updated list when returning to this screen, I copied the above code into the onRestart method, but now the database does not return anything. If I just set the array that goes into the adapter to {"a", "a", "a"} the list populates fine. Any ideas why the database works onCreate but not onRestart?
I think you can use ViewModel and livedata to observe any database change
I want to create button dynamically in my application. The buttons need to be created based on items fetched from database. What is the best way to achieve this. Should I go for grid layout or Linear layout. My layout is simple with max 3 buttons per row. Once the first row is complete the buttons should be placed in second row.
I scanned lot of similar questions(some had grid layout other were using Linear layout) but unable to decide what is the optimum way to implement this.
I am complete newbie in android application, so any code snippets would be really helpful. Apologies if someone feels this is a duplicate question (I searched a lot before posting but didn't find appropriate answer to layout to be used.)
Thanks.
Please try to use gridView same as bellow code.
// in xml write this code
<GridView
android:id="#+id/calendar"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:numColumns="3" />
// grid adapter
public class GridAdapter extends BaseAdapter {
private final Context _context;
private final List<String> list;
public GridAdapter(Context context, ArrayList<String> list) {
super();
this._context = context;
this.list = list;
}
public String getItem(int position) {
return list.get(position);
}
#Override
public int getCount() {
return list.size();
}
public View getView(int position, View convertView, ViewGroup parent) {
Button button = new Button(_context);
button.setText("button" + list.get(position));
return button;
}
#Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return 0;
}
}
/// in oncreate
gridView.setAdapter(new GridAdapter(getApplicationContext(),list);
I am trying to created a listview containing filenames. I want to set a additional information like file id with each list items, so when i click a filename, i have to get file id from it. please help me do this.
My sample code:
ListView listview = (ListView) findViewById(R.id.listview);
ArrayAdapter fileListAdapter = new ArrayAdapter(this, android.R.layout.simple_list_item_1, ['one','two','three']);
listview.setAdapter(fileListAdapter);
There are quite a few things involved here, so i'm providing you with an example of how you can achieve this (you can copy-paste and test):
public class MainActivity extends ListActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// First we simulate a pool of file names and IDs
String[] fileNames = {"fileName1", "fileName2", "fileName3"};
List<Integer> fileNameIds = new ArrayList<Integer>();
fileNameIds.add(1200);
fileNameIds.add(356);
fileNameIds.add(28);
// We call our custom Adapter
ArrayAdapter<String> adapter = new CustomAdapter(this, fileNames, fileNameIds);
// Finally we set the adapter to our list
setListAdapter(adapter);
}
// This is a custom adapter that uses ArrayAdapter for our purpose
// (as this is just an example you should consider using Base Adapter if you don't want
// to have a pool of filenames and a separate pool of ids)
class CustomAdapter extends ArrayAdapter<String>{
private final LayoutInflater INFLATER;
private final String[] FILE_NAMES;
private final List<Integer> FILE_NAME_IDS;
public CustomAdapter(Context context, String[] fileNames, List<Integer> fileNameIds) {
super(context, R.layout.custom_row, fileNames);
this.INFLATER = LayoutInflater.from(context);
this.FILE_NAMES = fileNames;
this.FILE_NAME_IDS = fileNameIds;
}
// HERE is where you can assign effectively an ID to your rows
#Override
public View getView(int position, View convertView, ViewGroup parent) {
// this is an object that takes advantage of the holder pattern
// it retains the state of our rows in the list
FileNameHolder holder;
if(convertView == null){
convertView = INFLATER.inflate(R.layout.custom_row, null); // inflate your custom row
// now you need to assign specific identifier to the list row that the holder will retain
// for you, so you can always get this id by calling getTag from the View object on your
// item click listeners
holder = new FileNameHolder();
holder.fileName = (TextView) convertView; //since i only have a texView in layout i don't need to call findByView
convertView.setTag(holder); // relate the view to a custom FileNameHolder object that retains file name and its ID
} else{
holder = (FileNameHolder) convertView.getTag();
}
holder.fileName.setText(FILE_NAMES[position]); // PROVIDE the list with file name description
holder.idFileName = FILE_NAME_IDS.get(position); // ASSIGN file name ID
return convertView;
}
}
// This is an example of catching a row clicked and get the custom ID that you assigned,
// from here you can use that ID as you need
#Override
protected void onListItemClick(ListView l, View v, int position, long id) {
// Here as you can see we obtain the object associated with the row that was clicked
FileNameHolder holder = (FileNameHolder) v.getTag();
// Here i provide a way you can test that you're always getting the correct file name and Id
Toast.makeText(this,
"File Name = " + holder.fileName.getText() +
", File ID = " + holder.idFileName,
Toast.LENGTH_SHORT).show();
}
// This is a class that takes advantage of the Holder Pattern and we use it to
// achieve what you need (remember this is just an example you should consider
// changing class and member access modifiers as you need)
class FileNameHolder{
Integer idFileName;
TextView fileName;
FileNameHolder() {
}
}
}
custom_row.xml is just a TextView (i took it from the simple_list_item_1 layout):
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#android:id/text1"
android:layout_width="match_parent"
android:layout_height="?android:attr/listPreferredItemHeight"
android:paddingStart="?android:attr/expandableListPreferredItemPaddingLeft"
android:textAppearance="?android:attr/textAppearanceMedium"
android:gravity="center_vertical"
/>
Hope it's useful... regards!!
As I'm learning the new world of JavaFX2 I stumbled on another annoying problem. I'm developing a program with multiple scenes (~10 scenes). For that I created a small class like this:
public class SceneSelector {
...
public void setScene(Stage stage, String fxmlfilename, ObservableList ol) throws Exception{
String s = "../" + fxmlfilename;
Parent root = FXMLLoader.load(getClass().getResource(s));
root.setUserData(ol);
Scene scene = new Scene(root);
stage.setScene(scene);
//show the stage
stage.show();
}
}
This class works good enough for switching between the scenes.
Now the problem is that I sometimes need to pass data from Scene1 to Scene2. I'm trying to do this by setting the setUserData() for the new scene which basicly works exept for one thing. How can I get the userdata when the new Scene is beeing initialized? (because the Nodes are still null at that time)
Code at scene1:
//Code connected to a button that opens the new Scene
private void openLabID(ActionEvent event) throws Exception {
final Stage primaryStage = (Stage) btnNewScene.getScene().getWindow();
ObservableList<Koe> olAfTeWerkenKoeien = DA_Koe.getAfTeWerkenKoeien();
ss.setScene(primaryStage, "GUI/scenes/koe/Koe.fxml", olAfTeWerkenKoeien);
}
Code at scene2:
public void initialize(URL url, ResourceBundle rb) {
Scene s = lbl.getScene();
ObservableList<Koe> olAfTeWerkenKoeien = (ObservableList<Koe>) s.getRoot().getUserData();
System.out.println(olAfTeWerkenKoeien.size());
}
Of course Scene s gives a null value at this point (because lbl is null at this point), so I wonder, is there a method that is beeing fired right after initialize?
When I attach this code to a button on Scene2, it works like a charm, but it should be loaded automatically.
EDIT:
The setting of the data with the setMyData() method is not a problem, however retrieving it is:
public ObservableList<Koe> getMyData() {
return this.myData;
}
How can I get the CustomScene object when a controller initializes? Because doing this below will result in a NullPointerException (because btnSluiten is not initialized just yet):
#Override
public void initialize(URL url, ResourceBundle rb) {
...
Stage stage = (Stage) btnSluiten.getScene().getWindow();
CustomScene cs = (CustomScene) stage.getScene();
ObservableList<Koe> olKoe = cs.getMyData();
System.out.println(olKoe.size());
}
I believe you missed the point within the Scene object. From the Scene class documentation we can see that:
The JavaFX Scene class is the container for all content in a scene graph.
Which means that the Scene object is just a container and as such it's not supposed to hold any data.
With that in mind, you can make another static object with a field such as
private static Label lbl;
...
public static Label getLbl()
{
return MyStaticObject.Lbl;
}
...
and use it to store your lbl (or whatever object suits your information) and then statically retrieve it.
I'm doing that to set the owner of my other Stage objects from my application. I hope it helps. Cheers
If you really want your scene to be meaningful (aka store specific user data) you can extend it:
public class FooScene extends Scene {
private ObservableList myData;
public setMyData(ObservableList data) {
this.myData = data;
//handle data
}
}
The easiest way to make sure setup code is called after scene initialized it to call it by yourself:
public class SceneSelector {
...
public void setScene(Stage stage, String fxmlfilename, ObservableList ol) throws Exception{
String s = "../" + fxmlfilename;
Parent root = FXMLLoader.load(getClass().getResource(s));
// first: add root to scene
FooScene scene = new FooScene(root);
// second: apply data to scene (or root)
scene.setMyData(ol);
stage.setScene(scene);
//show the stage
stage.show();
}
}
You can use controller for scenes and pass the data through controller:
String filePath1 = "../" + fxmlfilename;
URL location1 = YourController1.class.getResource(filePath1);
FXMLLoader fxmlLoader = new FXMLLoader();
fxmlLoader.setLocation(location1);
fxmlLoader.setBuilderFactory(new JavaFXBuilderFactory());
Parent root = (Node) fxmlLoader.load(location1.openStream());
YourController1 ctrl1 = (YourController1) fxmlLoader.getController();
Then you can assign data to the controller:
ctrl1.setUserData();
Finally, just show the scene as you want:
Scene scene = new Scene(root);
stage.setScene(scene);
//show the stage
stage.show();
In the initialize() method in the controller, just get data from controller as usual data object.
Some Addition of #Sergey Grinev :
Create A custom Scene :
package sample;
import javafx.scene.Parent;
import javafx.scene.Scene;
public class DataPassingScene extends Scene {
public DataPassingScene(Parent parent) {
super(parent);
}
String tafsir;
public String getTafsir() {
return tafsir;
}
public void setTafsir(String tafsir) {
this.tafsir = tafsir;
}
}
Suppose your Main Class Name is App.java, Then Create a method to show new Stage :
public static void showLayout (Stage primaryStage, String fxmlFileName, String stringData) throws IOException {
Parent root = FXMLLoader.load(Objects.requireNonNull(App.class.getClassLoader().getResource(fxmlFileName)));
DataPassingScene scene = new DataPassingScene(root);
scene.setTafsir(stringData); // Here we pass the data
primaryStage.setScene(scene);
primaryStage.show();
}
Now When you want to pass the Data, Call the above method from any Where / any class in your app with some Data :
String tafsir = "This My Data" ;
try {
App.showLayout(new Stage(), "showTafsirFxml.fxml",tafsir);
} catch (IOException e) {
e.printStackTrace();
}
Then Get the data in your controller. To get the scene you have to get the stage, and to get the stage you have use one of your elements of FXML, suppose here your element is a button, called closeButton, So :
#FXML
private Button closeButton;
#Override
public void initialize(URL url, ResourceBundle rb) {
Platform.runLater(new Runnable() {
#Override public void run() {
Stage stage = (Stage) closeButton.getScene().getWindow();
DataPassingScene scene = (DataPassingScene) stage.getScene();
String s = scene.getTafsir(); // Here we get the Data
if(s!=null)
System.out.println("This is Tafsir From Highlight Table: "+s);
else
System.out.println("Data Passing Null");
}});
}
because, You have to wait some Times in above runLater, because for initializing scene take some time. Other wise scene will be null.