Adding Layout to Container in loop fires an NullpointerException - java-me

I am developing s60 using j2me with LWUIT in Eclipse.
I am writing this method to draw list item and try to create List manually rather than using Lwuit list. Because as i posted in my last question here is LinK.. don't know why but it decreases performance.
So In below method i trying to create in which i'm adding adding two labels to layoutX Container and adding that Conatiner to layoutY Container and Adding that layoutY to BaseContainer so output is looks like list.
Method is here ...
private void drawAgendasListItem(Vector vector) {
Container containerX[] = new Container[vector.size()];
Container containerY[] = new Container[vector.size()];
if (featuredeventsForm.contains(baseContainer)) {
baseContainer.removeAll();
featuredeventsForm.removeComponent(baseContainer);
System.out.println("base Container is removed ");
}
BoxLayout layoutX = new BoxLayout(BoxLayout.X_AXIS);
BoxLayout layoutY = new BoxLayout(BoxLayout.Y_AXIS);
for (int i = 0; i < vector.size(); i++) {
try {
containerX[i].setLayout(layoutX);
containerY[i].setLayout(layoutY);
Label startTime = new Label();
Label description = new Label();
startTime.getStyle().setBgTransparency(0);
startTime.setText("start 10:20 Am");
startTime.getStyle().setMargin(0, 0, 0, 5);
description.getStyle().setBgTransparency(0);
description.setText("decriptionString");
containerX[i].getStyle().setPadding(0, 0, 2, 2);
containerX[i].addComponent(startTime);
containerX[i].addComponent(description);
containerY[i].addComponent(containerX[i]);
baseContainer.addComponent(i, containerX[i]);
System.out.println("Component added to base Container # " + i);
} catch (Exception e) {
System.out.println("Exception in drawAgendaListItem " + e);
}
}
featuredeventsForm.addComponent(baseContainer);
featuredeventsForm.invalidate();
featuredeventsForm.repaint();
System.out.println("All elements added and form repainted");
}
In above method when i try to assign layout to Container it fires an NullPointerException at line
containerX[i].setLayout(layoutX);.
I don't understand why it's happening, I was also try to comment that lines then it fires NullPointerException at line containerX[i].getStyle().setPadding(0, 0, 2, 2);.
please help ....

Based on the source code, my guess is that you think instantiating an array also populates it. That is not the case in Java.
In other word, if you think that containerX looks like:
[new Container, new Container,..., new Container]
in memory, that is incorrect. It actually looks like:
[null,null,...,null]
I think you need to add
containerX[i] = new Container();
containerY[i] = new Container();
at the beginning of the loop.
(Maybe you want to instantiate the contents of the arrays as subclasses of Container)

Related

UI thread slow to respond to Progress updaters on async Task method using VS2022 & Net6.0

I’ve run into a performance obstacle and I’m uncertain of the cause, all of this is running under VS2022 & Net6.0. As this is my 1st time using this combination of a modal windows form, and progress bar, with the work running on a background thread and two Progress objects updating the UI, the progress bar, and a text label, I don’t know where to attack the problem. Prior to placing the workload on a background thread, everything was snappy, searching a thousand files with about 600 lines of text in each, in about a minute. Naturally, the windows form was frozen during this, which is why the workload was placed on a background thread.
After doing so, the workload will be 25-50% complete before the UI starts displaying the values from the Progress objects, and overall, the entire process now takes 10x as long to complete. Progress objects aren’t skipping over any values sent to them, the UI thread just seems slow in getting the information. Likewise, if I try to drag the modal form to a new spot on the desktop it’s unresponsive for 20—30 seconds before it finally moves. One more thing, I can step through the code on the background thread and see it calling the Progress updaters, but the UI thread is just very slow in responding to them.
I could use some suggestions on how to uncover the problem or if clearly evident, point out where the likely problem could be. Here are the essential controls and methods used.
public class SearchProgressForm : Form
{
private System.Windows.Forms.Button btnSearch = new Button();
private System.Windows.Forms.TextBox txtTextSearch = new TextBox();
private System.Windows.Forms.Label lblSearchFile = new Label();
private System.Windows.Forms.ProgressBar SearchProgressBar = new ProgressBar();
public event LogSearchEventHandler SearchSucceededEvent;
protected void OnSearchSucceeded(LogSearchEventArguments p_eventArguments)
{
LogSearchEventHandler handler = SearchSucceededEvent;
if (handler != null)
{
handler(this, p_eventArguments);
}
}
private void InitializeComponent()
{
this.btnSearch.Name = "btnSearch";
this.btnSearch.Text = "Search";
this.btnSearch.Click += new System.EventHandler(this.btnSearch_Click);
this.lblSearchFile.Text = "Searching File: ";
this.txtTextSearch.Text = "search string";
}
public SearchProgressForm() { }
private void btnSearch_Click(object sender, EventArgs e)
{
this.SearchByText(this.txtTextSearch.Text);
}
private void SearchByText(string p_searchParameter)
{
// Setup a progress report for thr ProgressBar
var _progressBarUpdate = new Progress<int>(value =>
{
this.SearchProgressBar.Value = value;
this.SearchProgressBar.Refresh();
});
var _progressFileNameUpdate = new Progress<string>(value =>
{
this.lblSearchFile.Text = "Searching File For : " + value;
this.lblSearchFile.Refresh();
});
// Start search on a backgroud thread and report progress as it occurs
Task.Run(async () => await this.SearchByStringAsync(p_searchParameter, _progressBarUpdate, _progressFileNameUpdate));
}
private async Task SearchByStringAsync(string p_searchParameter, IProgress<int> p_progressBar, IProgress<string> p_progressFileName)
{
await Task.Delay(1);
TextFileReader textFileReader = new TextFileReader();
LogSearchEventArguments logSearchEventArguments = null;
long _sessionloopCount = 0;
long _totalTextLinesCount = this.GetTotalSearchCount(p_searchParameter, SearchType.TextString);
// Get file names from SQL table
var _logFiles = DataOperations.LogFileSortableList(null);
foreach (var log in _logFiles)
{
// Format a file name to be read from the file system
string _fileName = log.Directory + "\\" + log.FileName;
p_progressFileName.Report(log.FileName);
// If we've raised an event for this file, then stop iterating over remaning text
if (logSearchEventArguments != null)
{
logSearchEventArguments = null;
break;
}
// Read in file contents from file system
List<string> _fileContents = textFileReader.ReadAndReturnStringList(_fileName);
long _fileTotalRecordCount = _fileContents.Count;
long _fileRecordCount = 0;
foreach (var _line in _fileContents)
{
if (_line.ToUpper().Contains(p_searchParameter.ToUpper()))
{
// Raise an event so search parameter and file name can be captured in another form
logSearchEventArguments =
new LogSearchEventArguments
(
"TextSearch", p_searchParameter, SearchType.TextString, true, log,
new DateTime(
Convert.ToInt32("20" + log.FileName.Substring(14, 2)),
Convert.ToInt32(log.FileName.Substring(16, 2)),
Convert.ToInt32(log.FileName.Substring(18, 2)))
);
// We found a match, so no further searching is needed in this log file,
// and it's been flagged in the DB, so raise the event to save search parameter and file name
// then break out of this loop to get the next file to search in.
this.OnSearchSucceeded(logSearchEventArguments);
break;
}
// These calcs are based on actual searches performed
_fileRecordCount++;
_sessionloopCount++;
p_progressBar.Report(Convert.ToInt32((_sessionloopCount * 100) / _totalTextLinesCount));
}
// Because we exit a search as soon as the 1st match is made, need to resynch all counts
// and update the progress bar accordingly
if (_fileRecordCount < _fileTotalRecordCount)
{
long _countDifference = _fileTotalRecordCount - _fileRecordCount;
// Add count difference to sessionLoopCount and update progress bar
_sessionloopCount += _countDifference;
p_progressBar.Report(Convert.ToInt32((_sessionloopCount * 100) / _totalTextLinesCount));
}
}
//Search is complete set Progress to 100% and report before exiting
p_progressBar.Report(100);
// Close the modal SearchForm and exit
this.Close();
}
}
I solved this problem but I'm still not certain of what caused it. I eliminated the method "private void SearchByText(string p_searchParameter)" and moved the code there into the btnSearch_Click event handler so I could call my background worker "SearchByStringAsync" directly from the button click event handler.
I also updated the EFCore NuGet Packages, which were version Net6.0 to version 6.0.4, because of single line of code in my Async background method, "var _logFiles = DataOperations.LogFileSortableList(null)".
That call returned a Sortable BindingList, using BindingList <T>. Between the NuGet updates and a minor change on a custom comparer method in my BindingList <T> class, the windows modal form now updates the ProgressBar and Label text as expected, and the form now responds immediately to user interaction.

Unity Vuforia Google VR - Can't make onPointerEnter to GameObject change material for itself

I have two 3d buttons in my scene and when I gaze into any of the buttons it will invoke OnPointerEnter callback and saving the object the pointer gazed to.
Upon pressing Fire1 on the Gamepad I apply materials taken from Resources folder.
My problem started when I gazed into the second button, and pressing Fire1 button will awkwardly changed both buttons at the same time.
This is the script I attached to both of the buttons
using UnityEngine;
using UnityEngine.EventSystems;
using Vuforia;
using System.Collections;
public class TriggerMethods : MonoBehaviour, IPointerEnterHandler, IPointerExitHandler
{
Material _mat;
GameObject targetObject;
Renderer rend;
int i = 0;
// Update is called once per frame
void Update () {
if (Input.GetButtonDown("Fire1"))
TukarMat();
}
public void OnPointerEnter(PointerEventData eventData)
{
targetObject = ExecuteEvents.GetEventHandler<IPointerEnterHandler>(eventData.pointerEnter);
}
public void OnPointerExit(PointerEventData eventData)
{
targetObject = null;
}
public void TukarMat()
{
Debug.Log("Value i = " + i);
if (i == 0)
{
ApplyTexture(i);
i++;
}
else if (i == 1)
{
ApplyTexture(i);
i++;
}
else if (i == 2)
{
ApplyTexture(i);
i = 0;
}
}
void ApplyTexture(int i)
{
rend = targetObject.GetComponent<Renderer>();
rend.enabled = true;
switch (i)
{
case 0:
_mat = Resources.Load("Balut", typeof(Material)) as Material;
rend.sharedMaterial = _mat;
break;
case 1:
_mat = Resources.Load("Khasiat", typeof(Material)) as Material;
rend.sharedMaterial = _mat;
break;
case 2:
_mat = Resources.Load("Alma", typeof(Material)) as Material;
rend.sharedMaterial = _mat;
break;
default:
break;
}
}
I sensed some logic error and tried making another class to only manage object the pointer gazed to but I was getting more confused.
Hope getting some helps
Thank you
TukarMat() is beeing called on both buttons when you press Fire1. If targetObject is really becoming null this should give an error on first button since it's trying to get component from a null object. Else, it'll change both as you said. Make sure OnPointerExit is beeing called.
Also, it seems you are changing the shared material.
The documentation suggests:
Modifying sharedMaterial will change the appearance of all objects using this material, and change material settings that are stored in the project too.
It is not recommended to modify materials returned by sharedMaterial. If you want to modify the material of a renderer use material instead.
So, try changing the material property instead of sharedMaterial since it'll change the material for that object only.

Event firing continuously

I wrote a method which changes backcolor of the rows before painting gridview in devexpress. It works fine but I realized that my code begins slowing down. Then I've found that the event firing continuously. It never stops. How can I handle this? Is there any way to stop firing event manually after gridview painted or should I try to solve this problem with an another event or another method???
Here is my event:
private void gvStep_CustomDrawCell(object sender, DevExpress.XtraGrid.Views.Base.RowCellCustomDrawEventArgs e)
{
try
{
DataRowView drw = (DataRowView)gvStep.GetRow(e.RowHandle);
byte actionTypeID = (byte)drw.Row["ActionType"];
//string colorCode = (new DivaDs()).GetBackColor(actionTypeID);
string colorCode = divaDs.GetBackColor(actionTypeID);
Color backColor = ColorTranslator.FromHtml(colorCode);
e.Appearance.BackColor = backColor;
}
catch (Exception ex)
{
XtraMessageBox.Show(ex.Message);
}
}
public string GetBackColor(byte actionTypeID)
{
string color = string.Empty;
using (SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings[DivaSqlSiteConnString].ConnectionString))
{
using (SqlCommand cmd = new SqlCommand(#"Select BackColor from ActionTypes where ID = #actionTypeID"))
{
SqlParameter param = new SqlParameter("#actionTypeID", actionTypeID);
cmd.Parameters.Add(param);
cmd.Connection = conn;
conn.Open();
color = cmd.ExecuteScalar().ToString();
conn.Close();
}
}
return color;
}
My best guess is that some part of your code is just really slow.
The event only fires for each visible cell in the grid. If you attempt to debug the event, focus will shift to the debugger, and when you return to the application the cells need to be redrawn, causing the event to fire again, thus giving the impression that the event fires continuously. It does not, however.
Here are some pointers to improve performance:
You are constructing a new DivaDs every time the event fires
Instead, consider reusing the same instance of the class as a member variable
What happens in the constructor?
Take a closer look at the GetBackColor method or ColorTranslator.FromHtml and see if any modifications can be made to improve performance.
Update
It appears you are querying the database for each cell in the grid. This is a really bad idea.
A simple solution would be to preload all ActionTypes and their background colors (or at least the subset of ActionTypes that is displayed in the grid) before setting the grid's data source.
// member variable
private Dictionary<byte, Color> actionTypeColorDict;
void BuildActionTypeColorDictionary()
{
string connectionString = ConfigurationManager
.ConnectionStrings[DivaSqlSiteConnString].ConnectionString;
using (SqlConnection conn = new SqlConnection(connectionString))
using (SqlCommand cmd = conn.CreateCommand())
using (SqlDataAdapter adapter = new SqlDataAdapter(cmd))
{
// load all action type IDs and corresponding background color:
cmd.CommandText = #"SELECT ActionTypeID, BackColor FROM ActionTypes";
DataTable actionTypeTable = new DataTable();
adapter.Fill(actionTypeTable);
// build a dictionary consisting of action type IDs
// and their corresponding colors
actionTypeColorDict = actionTypeTable.AsEnumerable().ToDictionary(
r => r.Field<byte>("ActionTypeID"),
r => ColorTranslator.FromHtml(r.Field<string>("ColorCode")));
}
}
Call the BuildActionTypeColorDictionary method before setting the data source of the grid. In the RowStyle or CustomDrawCell events, use the new dictionary member to determine the background color. See the following modified version of your RowStyle code:
private void gvStep_RowStyle(object sender,DevExpress.XtraGrid.Views.Grid.RowStyleEventArgs e)
{
try
{
DataRow row = gvStep.GetDataRow(e.RowHandle);
if (row == null)
return;
byte actionTypeID = row.Field<byte>("ActionImage");
// look up color in the dictionary:
e.Appearance.BackColor = actionTypeColorDict[actionTypeID];
}
catch (Exception ex)
{
XtraMessageBox.Show(ex.Message);
}
}
How do you know it's firing continuously? Are you debbuging?
This code runs whenever the grid is redrawn, meaning whenever the form gets focus.
This event runs for each cell - so it will run quite a few times.
If you put a break-point in this event you'll never get out of it. It will break, you will debug, when it's done it will return focus to the form - causing the form to be redrawn using this event and the break-point is reached again.
And just a side note - Whenever I use that event I have to put e.Handled = true; in the code so that the cell isn't "drawn" by anyone but me :)
Finally, I found it. RowStyle event only fires same time with gridview's row count
private void gvStep_RowStyle(object sender, DevExpress.XtraGrid.Views.Grid.RowStyleEventArgs e)
{
try
{
DataRowView drw = (DataRowView)gridView1.GetRow(e.RowHandle);
if (drw == null)
return;
byte actionTypeID = (byte)drw.Row["ActionImage"];
string colorCode = divaDs.GetBackColor(actionTypeID);
Color backColor = ColorTranslator.FromHtml(colorCode);
e.Appearance.BackColor = backColor;
}
catch (Exception ex)
{
XtraMessageBox.Show(ex.Message);
}
}

How to display the images in listview

I am working with JavaFX2.0.I need to show the thumbnail images in listview.I am writing the code as below.
ObservableList<BufferedImage> imageList = FXCollections.observableArrayList();
try {
for (int i = 1; i <= pdf.getPageCount(); i++) {
BufferedImage pageImage = pdf.getPageAsImage(i);
imageList.add(pageImage);
} catch (PdfException e) {
_logger.error("Error :" + e.getMessage());
}
thumbnailsList.setItems(imageList);
Here thumbnailsList is the fx:id of the listview.But if i use this code i am getting image object and not an image.Can any one tell me that how can i get the image in listview.
Thank You.
You could use a sample from
http://docs.oracle.com/javafx/2/ui_controls/list-view.htm
which is called "Example 11-4 Creating a Cell Factory".
You have to set custom cell factory. And instead of Rectangle, put an ImageView there.

How do I block access to a method until animations are complete

I have a Silverlight app. that has a basic animation where a rectangle is animated to a new position. The animation consists of two DoubleAnimation() - one transforms the X, the other transforms the Y. It works OK.
I basically want to block any other calls to this animate method until the first two animations have completed. I see that the DoubleAnimation() class has a Completed event it fires but I haven't been successful in constructing any kind of code that successfully blocks until both have completed.
I attempted to use Monitor.Enter on a private member when entering the method, then releasing the lock from one of the animations Completed event, but my attempts at chaining the two events (so the lock isn't released until both have completed) haven't been successful.
Here's what the animation method looks like:
public void AnimateRectangle(Rectangle rect, double newX, double newY)
{
var xIsComplete = false;
Duration duration = new Duration(new TimeSpan(0, 0, 0, 1, 350));
var easing = new ElasticEase() { EasingMode = EasingMode.EaseOut, Oscillations = 1, Springiness = 4 };
var animateX = new DoubleAnimation();
var animateY = new DoubleAnimation();
animateX.EasingFunction = easing;
animateX.Duration = duration;
animateY.EasingFunction = easing;
animateY.Duration = duration;
var sb = new Storyboard();
sb.Duration = duration;
sb.Children.Add(animateX);
sb.Children.Add(animateY);
Storyboard.SetTarget(animateX, rect);
Storyboard.SetTargetProperty(animateX, new PropertyPath("(Canvas.Left)"));
Storyboard.SetTarget(animateY, rect);
Storyboard.SetTargetProperty(animateY, new PropertyPath("(Canvas.Top)"));
animateX.To = newX;
animateY.To = newY;
sb.Begin();
}
EDIT (added more info)
I ran into this initially because I was calling this method from another method (as it processed items it made a call to the animation). I noticed that the items didn't end up where I expected them to. The new X/Y coordinates I pass in are based on the items current location, so if it was called multiple times before it finished, it ended up in the wrong location. As a test I added a button that only ran the animation once. It worked. However, if I click on the button a bunch of times in a row I see the same behavior as before: items end up in the wrong location.
Yes, it appears Silverlight animations are run on the main UI thread. One of the tests I tried I added two properties that flagged whether both animations had completed yet. In the AnimateRectange() method I checked them inside of a while loop (calling Thread.Sleep). This loop never completed (so it's definitely on the same thread).
So I created a queue to process the animations in order:
private void ProcessAnimationQueue()
{
var items = this.m_animationQueue.GetEnumerator();
while (items.MoveNext())
{
while (this.m_isXanimationInProgress || this.m_isYanimationInProgress)
{
System.Threading.Thread.Sleep(100);
}
var item = items.Current;
Dispatcher.BeginInvoke(() => this.AnimateRectangle(item.Rect.Rect, item.X, item.Y));
}
}
Then I call my initial routine (which queues up the animations) and call this method on a new thread. I see the same results.
As far as I am aware all of the animations in Silverlight are happening on the UI thread anyway. I am guessing that only the UI thread is calling this animation function anyway, so I am not sure that using locking will help. Do you really want to be blocking the entire thread or just preventing another animation from starting?
I would suggest something more like this:
private bool isAnimating = false;
public void AnimateRectangle(Rectangle rect, double newX, double newY)
{
if (isAnimating)
return;
// rest of animation code
sb.Completed += (sender, e) =>
{
isAnimating = false;
};
isAnimating = true;
sb.Begin();
}
Just keep track of whether or not you are currently animating with a flag and return early if you are. If you don't want to lose potential animations your other option is to keep some kind of a queue for animation which you could check/start when each animation has completed.
This question really peaked my interest. In fact I'm going to include it in my next blog post.
Boiling it down, just to be sure we are talking about the same thing, fundementally you don't want to block the call to AnimateRectangle you just want to "queue" the call so that once any outstanding call has completed its animation this "queued" call gets executed. By extension you may need to queue several calls if a previous call hasn't even started yet.
So we need two things:-
A means to treat what are essentially asynchronous operations (sb.Begin to Completed event) as a sequential operation, one operation only starting when the previous has completed.
A means to queue additional operations when one or more operations are yet to complete.
AsyncOperationService
Item 1 comes up in a zillion different ways in Silverlight due to the asynchronous nature of so many things. I solve this issue with a simple asynchronous operation runner blogged here. Add the AsyncOperationService code to your project.
AsyncOperationQueue
Its item 2 that really took my interest. The variation here is that whilst an existing set of operations are in progress there is demand to add another. For a general case solution we'd need a thread-safe means of including another operation.
Here is the bare-bones of a AsyncOperationQueue:-
public class AsyncOperationQueue
{
readonly Queue<AsyncOperation> myQueue = new Queue<AsyncOperation>();
AsyncOperation myCurrentOp = null;
public void Enqueue(AsyncOperation op)
{
bool start = false;
lock (myQueue)
{
if (myCurrentOp != null)
{
myQueue.Enqueue(op);
}
else
{
myCurrentOp = op;
start = true;
}
}
if (start)
DequeueOps().Run(delegate { });
}
private AsyncOperation GetNextOperation()
{
lock (myQueue)
{
myCurrentOp = (myQueue.Count > 0) ? myQueue.Dequeue() : null;
return myCurrentOp;
}
}
private IEnumerable<AsyncOperation> DequeueOps()
{
AsyncOperation nextOp = myCurrentOp;
while (nextOp != null)
{
yield return nextOp;
nextOp = GetNextOperation();
}
}
}
Putting it to use
First thing to do is convert your existing AnimateRectangle method into a GetAnimateRectangleOp that returns a AsyncOperation. Like this:-
public AsyncOperation GetAnimateRectangleOp(Rectangle rect, double newX, double newY)
{
return (completed) =>
{
// Code identical to the body of your original AnimateRectangle method.
sb.Begin();
sb.Completed += (s, args) => completed(null);
};
}
We need to hold an instance of the AsyncOperationQueue:-
private AsyncOperationQueue myAnimationQueue = new AsyncOperationQueue();
Finally we need to re-create AnimateRectangle that enqueues the operation to the queue:-
public void AnimateRectangle(Rectangle rect, double newX, double newY)
{
myAnimationQueue.Enqueue(GetAnimateRectangleOp(rect, newX, newY)
}

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