I have a an ArrayList<Color> colorList for my list view with an ArrayAdapter. My POJO like this:
public class Color {
int id;
String name;
//getter setter
}
Everything is fetched from the server. so the id of each color object will match an id in the DB table.
In my ArrayAdapter's getView I am setting the tag with an id from the database.
holder.imageButton.setTag(item.getId()); //color id from database
holder.imageButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
int id = (Integer) v.getTag();
new DeleteColor(id).execute();
}
});
In the above code I am sending the clicked item's id to the server for deletion
What is the easy way to remove an item from my listView?
What I'm doing right now is:
class DeleteColor extends AsyncTask<String, String, String> {
int id;
public DeleteColor (int id) {
this.id = id;
}
#Override
protected String doInBackground (String ... args) {
MyManager.INSTANCE.getService().deleteColor(id, new Callback<Integer>() {
#Override
public void success(Integer id, Response response) {
//loop through the colorlist to find which one to remove
for (int i = 0; i < colorList.size(); i++) {
Color c = colorList.get(i);
if (c.getId() == id) {
colorList.remove(c);
adapter.notifyDataSetChanged();
break;
}
}
}
#Override
public void failure(RetrofitError retrofitError) {
}
});
return "";
}
}
As you can see, I am looping through the entire colorList to find out the one that has the id I want removed and then removing it. Is this a good approach to achieve this?
Question
How can I avoid looping through the entire colorList to find the one that needs to be deleted.
You have the id of the object you want to remove from the list.
Use that id to get the object, then use the ArrayList method indexOf(Object object) to find the index of the object in your list and remove it.
There technically is no way to directly access an item in a list.
In school we built a list in Java ourselves and it consisted of different entries that were connected one to another. But the first only was connected to the second and that in turn only to the third. So you couldn't even access the object on the second place, without beginning at the top. To access anything you had to iterate the list.
I just read Sound Conception's answer and I'm pretty sure that the indexOf(Object)-method itself iterates through the whole list (unless the Java developers did some magic, which actually could be. ;) I'm not a professional and haven't looked into the code of that method). But your manual looping probably is the most efficient way.
I don't think, there is a practical difference in execution time. So you might want to use Sound Conception's method to keep the code simple. It's totally up to you!
There is one another way if you set the item position as tag on your view.....
Then v.getId() will give you the position clicked and that you can directly remove from your list as arraylist.remove(positionclicked);
Related
I humbly ask for help in order to solve this problem. I successfully take a quick guide to learn more about save and load state of the game. Basically first, I know how to use PlayerPrefsto store basic string, int, and float.
Now, looking for a more effective way to store saved files via serialization. At first, after my first few researches online, I watch some video tutorial and only provides storing basic fields (int, string, bool, float, etc.) and saved in a created file. I attempt to try it on classes but didn't worked unless I marked as [Serializable].
Next, trying to save Gameobject created, prefabs or not, didn't work and it requires to serialize that class itself that is "GameObject". I took first attempt using this guide from StackOverflow with the accepted answer, I do understand and saving a GameObject or other custom classes require to store it and converted into .xml file.
Here's my two main problem need to resolve. the first one is that the runtime returned NullPointerException after I ensured all of the necessary objects are created as new. The error stopped at this line (ask for more code source if you need):
DataContractSerializer ds = new DataContractSerializer (data2.GetType ()); // --> Serialize to .xml file.
MemoryStream stream = new MemoryStream();
ds.WriteObject (stream, data2); // --> The error stops here.
stream.Seek (0, SeekOrigin.Begin);
file.Write (stream.GetBuffer (), 0, stream.GetBuffer ().Length);
file.Close();
As you can see, this is the part of the code where you can save and stored in a file created on a persistent file directory for the stored classes such as GameObject, List, and/or other custom classes.
The second problem will be tackled after the first problem is resolved. The second problem involves loading last state saved. For the normal fields such as integer or string, using BinaryFormatter and FileStream works well to load stored values form a file created last time. I tried that on stored custom classes such as GameObject but it required a different method like this one but it is a bit hard to understand how to translate it in Unity and still observe some ways to work it out, the best way to load stored classes from a file.
Here is the class I'm trying to deserialize a class that contains the following fields inside.
[DataContract]
public class TreeData2 {
// - - - Spouse - - -
[DataMember] private List<GameObject> _masters;
public List<GameObject> masters {
get { return _masters; }
set { _masters = value; }
}
[DataMember] private List<GameObject> _targets;
public List<GameObject> targets {
get { return _targets; }
set { _targets = value; }
}
[DataMember] private List<FamilyDatabase> _familyGroup;
public List<FamilyDatabase> familyGroup {
get { return _familyGroup; }
set { _familyGroup = value; }
}
[DataMember] private GameObject _node;
public GameObject node {
get { return _node; }
set { _node = value; }
}
[DataMember] private List<string> _mothers;
public List<string> mothers {
get { return _mothers; }
set { _mothers = value; }
}
[DataMember] private List<string> _fathers;
public List<string> fathers {
get { return _fathers; }
set { _fathers = value; }
}
[DataMember] private List<GenerationDatabase> _genDb;
public List<GenerationDatabase> genDb {
get { return _genDb; }
set { _genDb = value; }
}
// - - - Root Action - - -
[DataMember] private List<GameObject> _child;
public List<GameObject> child {
get { return _child; }
set { _child = value; }
}
// Gen Database (Main)
[DataMember] private List<string> _mothersDB;
public List<string> mothersDB {
get { return _mothersDB; }
set { _mothersDB = value; }
}
[DataMember] private List<string> _fathersDB;
public List<string> fathersDB {
get { return _fathersDB; }
set { _fathersDB = value; }
}
[DataMember] private List<GameObject> _mastersDB;
public List<GameObject> mastersDB {
get { return _mastersDB; }
set { _mastersDB = value; }
}
[DataMember] private List<GameObject> _targetsDB;
public List<GameObject> targetsDB {
get { return _targetsDB; }
set { _targetsDB = value; }
}
[DataMember] private List<string> _mothersT;
public List<string> mothersT {
get { return _mothersT; }
set { _mothersT = value; }
}
[DataMember] private List<string> _fathersT;
public List<string> fathersT {
get { return _fathersT; }
set { _fathersT = value; }
}
[DataMember] private List<GameObject> _mastersT;
public List<GameObject> mastersT {
get { return _mastersT; }
set { _mastersT = value; }
}
[DataMember] private List<GameObject> _targetsT;
public List<GameObject> targetsT {
get { return _targetsT; }
set { _targetsT = value; }
}
}
data2 is the variable name of the TreeData2 class and yes I'm making a family tree like structure via Unity for the game that shows progress of unlocking and storing lists of the branches. Here's the recap with the mentioned variable name while serializing GameObject and List classes.
FileStream file = File.Create (Application.persistentDataPath + "/check/treeData2.dat");
TreeData2 data2 = new TreeData2();
. . .
DataContractSerializer ds = new DataContractSerializer (data2.GetType ());
MemoryStream stream = new MemoryStream();
ds.WriteObject (stream, data2); // --> Error stops here. Returns NullPointerException due to failed in parsing in .xml file in storing GameObject classes and List<T>.
stream.Seek (0, SeekOrigin.Begin);
file.Write (stream.GetBuffer (), 0, stream.GetBuffer ().Length);
file.Close();
string result = XElement.Parse(Encoding.ASCII.GetString(stream.GetBuffer()).Replace("\0", "")).ToString();
print ("SAVE TREE COMPLETE");
print ("Result: " + result);
Redirect from this original question from Game Development.
Let me start with clearing a confusion I find so often. 'Serializable' will serialize a class for display in inspector only. You can say that it will serialize your class into a format that can be represented by inspector. Often, serialize means convert into byte arrays, it doesn't have to be a byte array, it can be any other format, e.g. strings.
Unity does not allow you to save your gameobjects directly, however, it doesn't stop you from recreating them to reflect some previous state. A gameobject may have so many components, e.g. MeshRenderer, Camera, etc, and it could get rough serializing all that down, imagine some big hierarchy!.
Generally, you want to separate your behaviors from data, i.e. your MonoBehavior from model/data (not 3d model), its a common OOP practice. You can come up with how you can save and retrieve some data from disk. I used Json.Net to serialize my data models into json. That gave me flexibility to save it locally as well as send it over network, but its just an example.
For an example, if I had to serialize a user's inventory, I would make a class like this:
[Serializable]
public class Inventory
{
public List<InventoryItem> _items;
// Some serializable and transient variables
}
[Serializable]
public class InventoryItem
{
// Some serializable and transient variables
}
Then my Monobehaviour that would show inventory would look like this:
public class InventoryView : MonoBehaviour
{
public Inventory _inventory; //Now the inventory items show in the inspector also, because it is serialized.
void createViewFromInventory()
{ //... }
}
And now, anywhere I have reference to an Inventory object, I can serialize it however I wish to do so. With Json.Net, all I had to do looked something like this:
Inventory inv = getInventoryRef(); // get inventory here
string serializedInv = JsonConvert.Serialize(inv); // It converts it into json.
PlayerPrefs.Save("inventory", serializedInv); //
And in order to retrieve the saved inventory, I would do something like this:
void loadInventory()
{
string invStr = PreferPrefs.GetString("inventory");
Inventory inv = JsonConvert.Deserialize<Inventory>(invStr);
}
This way, monobehavior view classes need only ACT upon inventory state, but not save other components on the gameobject. Hope it helps.
Unfortunately, after several experiments to find the easy way to store GameObjects effectively without hassle, there is no shortcut in preserving files + game objects during save and load state. I decided to give up for banging my head too hard to go crazy in making expectations on saving scene in one go. There are many steps to understand it.
Right now, storing info on each game object's specified sections/components require complex serializable classes, a meticulous way for sharing and retrieving each part of data. Explanation on this link and for more effective way in preserving data (but still not on game object) via formatting into JSON file.
It is a wise choice to make a better roadmap for tracking last state from scratch if you want to make your own save/load state for both common variables, serializable classes, and game object.
However, there is another way to save and load GameObject using this solution found on this Unity Q&A section. It discusses about "SerializerHelper" that lets you serialize not only serialized classes but also game objects, scenes and other non-serializable classes. Check this forum as well in order to understand how it works. You can try this Unity package to try out saving/loading GO here to download. (Requires to register Dropbox account if needed.)
I am writing an application that is using a JavaFX8 TreeTableView. The tree table has three columns, two of which are String properties (name and value) and one which has a Canvas widget in it that draws a picture from from data from a database (waveforms). There is also a control on the application that allows the display (of all of the drawings) to be zoomed out or in (or for that matter scrolled left and right).
The name and value columns use StringProperty values from my data model so there are CellValueFactory set for those columns. The drawing column uses both a CellFactory and CellValueFactory like this:
// Waveform column
TreeTableColumn<DrawRow, WaveformTraceBox> waveColumn = new TreeTableColumn<>();
waveColumn.setCellFactory(new Callback<TreeTableColumn<DrawRow, WaveformTraceBox>, TreeTableCell<DrawRow, WaveformTraceBox>>() {
#Override
public TreeTableCell<DrawRow, WaveformTraceBox> call(TreeTableColumn<DrawRow, WaveformTraceBox> param) {
return new WaveformTraceBoxTreeTableViewCell<>();
}
});
waveColumn.setCellValueFactory(new Callback<TreeTableColumn.CellDataFeatures<DrawRow, WaveformTraceBox>, ObservableValue<WaveformTraceBox>>() {
#Override
public ObservableValue<WaveformTraceBox> call(TreeTableColumn.CellDataFeatures<DrawRow, WaveformTraceBox> param) {
return new ReadOnlyObjectWrapper<>(new WaveformTraceBox());
}
});
Where WaveformTraceBoxTreeTableViewCell is:
protected static class WaveformTraceBoxTreeTableViewCell<T> extends TreeTableCell<DrawRow, T> {
public WaveformTraceBoxTreeTableViewCell() {
super();
}
#Override
protected void updateItem(T value, boolean empty) {
super.updateItem(value, empty);
setText(null);
setGraphic(null);
if (!empty && getTreeTableRow().getItem() != null) {
getTreeTableRow().getItem().setTraceBox((WaveformTraceBox)value);
setGraphic((WaveformTraceBox) value);
}
}
DrawRow is my data model. When the user zooms out or in via the controls on the window the draw row model will notify it's associated Canvas drawing item to re-draw its display. The drawing of the display can take some time to do because of the large amount of data that needs to be processed to generate the display.
Now my problem: As the TreeTableView widget is scrolled it will ask for new Canvas widgets -- which get associated with DrawRow items from the data model. However widgets from the list that get scrolled off the screen will get thrown away by the tree widget.
I have found no way to tell if the item I am working with has been thrown away or is not being used any more. So the code is doing much more work than it needs to because it is trying to draw cells that are no longer being used or shown. Eventually this will cause other problems because of garbage collection I think.
So my real question is how can I tell if a cell has been abandoned by the tree table so I can stop trying to update it? Any help with this would greatly be appreciated. I am not able to find this anywhere on the various web searches I have done.
Do you need to worry here? What is still "drawing cells that are no longer being used"? Are you running some kind of update in a background thread on the WaveformTraceBox?
In any event, you've structured this pretty strangely.
First, (less important) why is your WaveformTraceBoxTreeTableViewCell generic? Surely you want
protected static class WaveformTraceBoxTreeTableViewCell extends TreeTableCell<DrawRow, WaveformTraceBox>
and then you can replace T with WaveformTraceBox throughout and get rid of the casts, etc.
Second: if I understand this correctly, WaveformTraceBox is a custom Node subclass of some kind; i.e. it's a UI component. The cell value factory shouldn't really return a UI component - it should return the data to display. The cell factory should then use some UI component to display the data.
That way, you can create a single WaveFormTraceBox in the cell implementation, and update the data it displays in the updateItem(...) method.
So something like:
// Waveform column
TreeTableColumn<DrawRow, WaveformData> waveColumn = new TreeTableColumn<>();
waveColumn.setCellFactory(new Callback<TreeTableColumn<DrawRow, WaveformData>, TreeTableCell<DrawRow, WaveformData>>() {
#Override
public TreeTableCell<DrawRow, WaveformData> call(TreeTableColumn<DrawRow, WaveformData> param) {
return new WaveformTraceBoxTreeTableViewCell();
}
});
waveColumn.setCellValueFactory(new Callback<TreeTableColumn.CellDataFeatures<DrawRow, WaveformData>, ObservableValue<WaveformData>>() {
#Override
public ObservableValue<WaveformTraceBox> call(TreeTableColumn.CellDataFeatures<DrawRow, WaveformTraceBox> param) {
return new ReadOnlyObjectWrapper<>(getDataToDisplayForItem(param.getValue()));
}
});
protected static class WaveformTraceBoxTreeTableViewCell extends TreeTableCell<DrawRow, WaveFormData> {
private WaveformTraceBox traceBox = new WaveformTraceBox();
public WaveformTraceBoxTreeTableViewCell() {
super();
}
#Override
protected void updateItem(WaveFormData value, boolean empty) {
super.updateItem(value, empty);
setText(null);
setGraphic(null);
if (!empty && getTreeTableRow().getItem() != null) {
traceBox.setData(value);
setGraphic(traceBox);
} else {
setGraphic(null);
}
}
}
Obviously you need to define the WaveFormData class to encapsulate the data your WaveFormTraceBox will display, and give the WaveFormTraceBox a setData(WaveFormData) method. If you are using any resources that need to be cleaned up, the invocation of setData(...) will indicate that the previous data is no longer being accessed by that WaveformTraceBox.
Given an arbitrary field on a Java object, I want to create an Observable that will watch that field and push a new result to an Observer every time the value of the field changes. ReactiveCocoa has a macro called RACObserve, which appears to do exactly this.
I want to know how to implement similar functionality using RxJava.
For example, say I had the following simple class:
public class Foo {
enum State {
Idle,
Ready,
Error
}
private State currentState = State.Idle;
//methods that can change currentState
}
I want to create an Observable<State> that will push the new state to an Observer every time something changes the value of currentState.
In ReactiveCocoa, it looks like I would write something sort of like the following (please excuse my pseudo Objective-C):
[RACObserve(self, currentState) subscribeNext:^(NSString *newState) {
NSLog(#"%#", newState);
}];
How would I achieve similar functionality in RxJava? I'm thinking that I may need to wrap all changes to currentState in a setter, but it's not clear to me where I should then call Observable.create and how to feed the changes of currentState to an Observer.
ReactiveCocoa is actually more similar to ReactiveUI (http://www.reactiveui.net) than just plain Rx. And in ReactiveUI, you can use this.WhenAnyValue(x => x.PropName) to do exactly what you want.
I stumbled across this same problem recently, I ended up using PropertyChangeListener, which will emit an object when a property is changed, see the following:
Update Listener:
public class GameUpdateListener {
public static Observable<Object> changed(Game game) {
final BehaviorSubject<Object> subject = BehaviorSubject.create((Object)game);
game.addPropertyChangeListener(new PropertyChangeListener() {
#Override
public void propertyChange(PropertyChangeEvent propertyChangeEvent) {
subject.onNext( (Object)propertyChangeEvent.getNewValue());
}
});
return subject;
}
}
Some custom object:
public class Game {
private PropertyChangeSupport pcs = new PropertyChangeSupport(this);
...
public setSomeField(String field){
this.field = field;
pcs.firePropertyChange("field", this.field, field);
}
public void addPropertyChangeListener(PropertyChangeListener propertyChangeListener) {
pcs.addPropertyChangeListener(propertyChangeListener);
}
...
}
Observe:
Game game = new Game();
GameUpdateListener listener = new GameUpdateListener();
final Observable<Object> gameObserver = listener.changed(game);
gameObserver.subscribe(new Action1<Object>() {
#Override
public void call(Object o) {
Log.e(TAG, "Object Changed");
}
});
game.setSomeField("New value");
This will work fine as long as you don't need to instantiate your object again. Perhaps a solution to this is to create a local setter method and emit a change there.
Since your question title contains "or Rx.NET", here is my suggestion (I dunno bout RxJava, you may find something similar).
You probably will have to leverage some sort of mechanism in the setter. The standard way in .NET is by using the INotifyPropertyChanged interface.
Then by firing the events, you can create an IObservable<T> from this stream by using
Observable.FromEvent<TEvent, TArgs>()
You can find a really good example of what you want to do (.NET) here.
(credits to Rob Foncesa-Ensor)
I think what you are after is a Subject<T>. It implements IObserver<T>, so you can call OnNext(T) to fire a new value, as well as IObservable<T>, which you can expose it as publicly so it can be subscribed to.
If you need it to fire the latest value to new subscribers, you can use a ReplaySubject<T> with a buffer size of 1.
Here's a basic implementation:
public class SomeService
{
private Subject<int> values = new Subject<int>();
public IObservable<T> Values
{
get
{
// AsObservable prevents it from being cast back to Subject
return values.AsObservable();
}
}
// Private; called by some internal mechanism
private void SetValue(int newValue)
{
newValue.OnNext(newValue);
}
}
I have a CellTable where I want to add several links to a row when I click an add button. Right now Im facing the problem that when I click the add button the link will be added to all rows in that column. Somehow it feels like I only can add things to columns.
// shows project column
final MultipleLinkTextCell projectCell = new MultipleLinkTextCell();
final Column<Booking, String> projectColumn = new Column<Booking, String>(
projectCell) {
#Override
public String getValue(Booking project) {
return "";
}
};
getView().getTimeTable().addColumn(projectColumn, "Tasks");
An Example with Buttons
#Override
protected void render(com.google.gwt.cell.client.Cell.Context context,
SafeHtml data, SafeHtmlBuilder sb) {
String string = "";
for (int i = 0; i < value; i++) {
string += "<button type=\"button\" style=\" height:20px; width:22px\">";
}
sb.appendHtmlConstant(string);
if (data != null) {
sb.append(data);
}
}
Im thinking about to use the Anchor widget because I can handle the placemanager from gwtp with it. But still I dont know how to add widgets to a specific row.
//Update:
I did it like this now, it works, but its better to use the revealmanager. The hardcoded link is kinda bad because I always need to change the reference to the link when I change the webserver. I get a string with several values splitted by a commar.
#Override
protected void render(com.google.gwt.cell.client.Cell.Context context,
SafeHtml data, SafeHtmlBuilder sb) {
String stringData = data.asString();
String[] splitResult = stringData.split(",");
for (int i = 0; i < splitResult.length; i++) {
if (!splitResult[i].equals("")) {
sb.appendHtmlConstant("<div><a href=\"http://127.0.0.1:8888/gwtpTimeTracking.html?gwt.codesvr=127.0.0.1:9997#project;projectid="+splitResult[i].substring(0, 7)+"\">"
+ splitResult[i].substring(0, 7) + "</a></div>");
}
}
You can't use any Widgets in CellWidgets.
However you can create your custom cell that mimics it or create an ActionCell and add a VaueUpdater that fires a PlaceRequest Event.
For adding the link to a specific row you have to add a field (i..e List<String> links) to your DTO that is rendered in your CellTable. When you click on the "Add" button you have to modify the field of the specific DTO in your list.
MyDTO obj = // get the specific DTO from the DataProvider
obj.setLinks(LIST OF LINKS);
In the render method of your custom cell you check the field (i..e links) and either render out the links or not.
Where does the value data in your render method come from ?
does anyone know how to trigger the "Show More" functionality of a GWT CellTree programmatically, without having to click on the Show More button?
My aim is to implement a kind of pager that increments the number of elements displayed when the user scrolls down a ScollPanel, so it would be something like:
//inside pager class
onScroll(ScrollEvent)
{
//here I would call CellTree's show more
}
I've been looking the CellTree and CellTreeNodeView classes code but I couldn't find a clear way to do it.
I know the class CellTreeNodeView has a showMore function which is the one who performs this action, but I don't know how to get it called from another class. I'd need a CellTreeNodeView object, and dont' know how to get it.
Thanks!
It is a package protected method in a package protected class CellTreeNodeView i.e only code in com.google.gwt.user.cellview.client can invoke it.
void showMore()
Extremely hacky solution
1) The only way around it is . Copy CellTreeNodeView and CellTree into your code base (maintain the package )
2) Change the accessors to public to allow you to invoke showMore as per your requirement.
3) Ensure you test for all possible flows.
4) Ensure the copied classes in your code base appear in a higher classpath hieararchy to GWT Compiler than gwt-user jar thus ensuring your modified classes get picked up rather than original ones.
Finally I got it working exactly as I wanted, and without having to copy the code from the protected original GWT.
The point was firing the same event as the "Show more" button, so I created a fake onMouseDown event, and triggered it with the show more button as the target:
final ScrollPanel sp = new ScrollPanel();
sp.addScrollHandler(new ScrollHandler() {
#Override
public void onScroll(ScrollEvent event)
{
int maxScrollBottom = sp.getWidget().getOffsetHeight()
- sp.getOffsetHeight();
if (sp.getVerticalScrollPosition() >= maxScrollBottom) {
NativeEvent clickEvent = Document.get().createMouseDownEvent(0,0,0,0,0,false,false,false,false,0);
Element target = (Element) cellTree.getCellTree().getElement().getLastChild().getFirstChild().getLastChild();
target.dispatchEvent(clickEvent);
}
}
});
Thank you a lot, anyway! :D
My workaround is this one:
public static void makeShowMoreVisible(Element element, boolean isVisible) {
ArrayList<Element> result = new ArrayList<Element>();
findShowMore(result, element);
for (Element elt : result) {
if (isVisible) {
element.getStyle().clearDisplay();
} else {
element.getStyle().setDisplay(Display.NONE);
}
}
}
private static void findShowMore(ArrayList res, Element element) {
String c;
if (element == null) {
return;
}
if (element.getInnerText().equals("Show more")) {
res.add(element);
}
for (int i = 0; i < DOM.getChildCount(element); i++) {
Element child = DOM.getChild(element, i);
findShowMore(res, child);
}
}