I am using timepicker in my application but whenever I give it a default value then NullReferenceException appears in valuechange function.My code is
private void timePicker1_ValueChanged(object sender, DateTimeValueChangedEventArgs e)
{
var time = (DateTime)timePicker1.Value;
// time.ToShortTimeString()
MessageBox.Show(time.ToString("H:mm"));
writeTimeFile(time);
ResetAlarm();
setTheAlarm();
}
Actually whenever I start my application,the timepicker shows current time but I want it to show some specific value say 00:00 or 12:00.
Make sure you are setting the value of your time picker object correctly. This worked for me. Also verify something else isn't throwing the NullReferenceException.
public TimePage()
{
InitializeComponent();
// setting default value for TimePicker here
EventTimePicker.Value = DateTime.Parse("12:00 AM");
}
private void TimePicker_ValueChanged(object sender, DateTimeValueChangedEventArgs e)
{
var time = (DateTime) EventTimePicker.Value;
MessageBox.Show(time.ToShortTimeString());
}
Related
MainView include InformationCOmponent:
#Push
#Route
public class MainView extends VerticalLayout {
InformationComponent infoComponent;
public MainView(#Autowired StudentRepository studentRepo, #Autowired Job jobImportCsv, #Autowired JobLauncher jobLauncher, #Value("${file.local-tmp-file}") String inputFile) {
[...] // some stuffs
infoComponent = new InformationComponent(studentRepo);
add(infoComponent);
}
//update when job process is over
private void uploadFileSuccceed() {
infoComponent.update(myUploadComponent.getFile());
}
InformationComponent:
public class InformationComponent extends HorizontalLayout {
StudentRepository studentRepo;
Label nbLineInFile = new Label();
VerticalLayout componentLeft = new VerticalLayout();;
VerticalLayout componentRight = new VerticalLayout();;
public InformationComponent(StudentRepository studentRepo) {
[...] // some init and style stuff
addLine("Nombre de lignes dans le fichier", nbLineInFile);
}
private void addLine(String label, Label value) {
componentLeft.add(new Label(label));
componentRight.add(value);
}
public void update(File file) {
try {
long nbLines = Files.lines(file.toPath(), Charset.defaultCharset()).count();
System.out.println("UPDATED! " +nbLines); // value is display in console ok!
UI.getCurrent().access(() -> nbLineInFile.setText(nbLines)); // UI is not updated!!
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}
When I call InformationComponent from MainView the Label is not update in the browser.
UI.getCurrent().access(() -> nbLineInFile.setText(nbLines))
also try wwith #Push(PushMode.MANUAL) and ui.push(); but doesn't work either...
Complete source code is here: https://github.com/Tyvain/ProcessUploadedFile-Vaadin_SpringBatch/tree/push-not-working
I suspect the problem here is that uploadFileSuccceed() is run from a background thread, in which case UI.getCurrent() will return null. This would cause a NullPointerException that either kills the background thread or alternatively the exception is caught and silently ignored by the caller. Another alternative is that uploadFileSuccceed() happens through a different browser window and thus also a different UI instance, which means that the changes would be pushed in the context of the wrong UI.
For exactly these reasons, UI.getCurrent().access(...) is generally an anti pattern, even though it's unfortunately quite widely used in old examples.
You can check whether this is the cause of your problem by logging the value of UI.getCurrent() in the beginning of the update method, and comparing that to the value of UI.getCurrent() e.g. in the constructor of InformationComponent.
To properly fix the problem, you should pass the correct UI instance through the entire chain of events originating from whatever triggers the background processing to start. You should also note that it might be tempting to use the getUI() method that is available in any Component subclass, but that method is not thread safe and should thus be avoided in background threads.
As a final notice, I would recommend using the Span or Text component instead of Label in cases like this. In Vaadin 10, the Label component has been changed to use the <label> HTML element, which means that it's mainly intended to be used as the label of an input component.
Based on information provided by Leif you should do something like the following example.
At runtime, when this HorizontalLayout subclass object is attached to a parent UI object, its onAttach method is called. At that point we can remember the UI by storing its reference is a member variable named ui. Actually, an Optional<UI> is returned rather than a UI object, so we need to test for null, though it should never be null at point of onAttach.
public class InformationComponent extends HorizontalLayout {
UI ui;
StudentRepository studentRepo;
Label nbLineInFile = new Label();
VerticalLayout componentLeft = new VerticalLayout();;
VerticalLayout componentRight = new VerticalLayout();;
public InformationComponent(StudentRepository studentRepo) {
[...] // some init and style stuff
addLine("Nombre de lignes dans le fichier", nbLineInFile);
}
private void addLine(String label, Label value) {
componentLeft.add(new Label(label));
componentRight.add(value);
}
public void update(File file) {
try {
long nbLines = Files.lines(file.toPath(), Charset.defaultCharset()).count();
System.out.println("UPDATED! " +nbLines); // value is display in console ok!
this.ui.access(() -> nbLineInFile.setText(nbLines)); // UI is not updated!!
} catch (IOException e) {
throw new RuntimeException(e);
} catch (UIDetachedException e) {
// Do here what is needed to do if UI is no longer attached, user has closed the browser
}
#Override // Called when this component (this `HorizontalLayout`) is attached to a `UI` object.
public void onAttach() {
ui = this.getUI().orElseThrow( () -> new IllegalStateException("No UI found, which should be impossible at point of `onAttach` being called.") );
}
I've read several related posts and even posted and answer here but it seems like I was not able to solve the problem.
I have 3 Activities:
Act1 (main)
Act2
Act3
When going back and forth Act1->Act2 and Act2->Act1 I get no issues
When going Act2->Act3 I get no issues
When going Act3->Act2 I get occasional crashes with the following error: java.lang.IllegalStateException: trying to requery an already closed cursor android.database.sqlite.SQLiteCursor#.... This is a ListView cursor.
What I tried:
1. Adding stopManagingCursor(currentCursor);to the onPause() of Act2 so I stop managing the cursor when leaving Act2 to Act3
protected void onPause()
{
Log.i(getClass().getName() + ".onPause", "Hi!");
super.onPause();
saveState();
//Make sure you get rid of the cursor when leaving to another Activity
//Prevents: ...Unable to resume activity... trying to requery an already closed cursor
Cursor currentCursor = ((SimpleCursorAdapter)getListAdapter()).getCursor();
stopManagingCursor(currentCursor);
}
When returning back from Act3 to Act2 I do the following:
private void populateCompetitorsListView()
{
ListAdapter currentListAdapter = getListAdapter();
Cursor currentCursor = null;
Cursor tournamentStocksCursor = null;
if(currentListAdapter != null)
{
currentCursor = ((SimpleCursorAdapter)currentListAdapter).getCursor();
if(currentCursor != null)
{
//might be redundant, not sure
stopManagingCursor(currentCursor);
// Get all of the stocks from the database and create the item list
tournamentStocksCursor = mDbHelper.retrieveTrounamentStocks(mTournamentRowId);
((SimpleCursorAdapter)currentListAdapter).changeCursor(tournamentStocksCursor);
}
else
{
tournamentStocksCursor = mDbHelper.retrieveTrounamentStocks(mTournamentRowId);
}
}
else
{
tournamentStocksCursor = mDbHelper.retrieveTrounamentStocks(mTournamentRowId);
}
startManagingCursor(tournamentStocksCursor);
//Create an array to specify the fields we want to display in the list (only name)
String[] from = new String[] {StournamentConstants.TblStocks.COLUMN_NAME, StournamentConstants.TblTournamentsStocks.COLUMN_SCORE};
// and an array of the fields we want to bind those fields to (in this case just name)
int[] to = new int[]{R.id.competitor_name, R.id.competitor_score};
// Now create an array adapter and set it to display using our row
SimpleCursorAdapter tournamentStocks = new SimpleCursorAdapter(this, R.layout.competitor_row, tournamentStocksCursor, from, to);
//tournamentStocks.convertToString(tournamentStocksCursor);
setListAdapter(tournamentStocks);
}
So I make sure I invalidate the cursor and use a different one. I found out that when I go Act3->Act2 the system will sometimes use the same cursor for the List View and sometimes it will have a different one.
This is hard to debug and I was never able to catch a crashing system while debugging. I suspect this has to do with the time it takes to debug (long) and the time it takes to run the app (much shorter, no pause due to breakpoints).
In Act2 I use the following Intent and expect no result:
protected void onListItemClick(ListView l, View v, int position, long id)
{
super.onListItemClick(l, v, position, id);
Intent intent = new Intent(this, ActivityCompetitorDetails.class);
intent.putExtra(StournamentConstants.App.competitorId, id);
intent.putExtra(StournamentConstants.App.tournamentId, mTournamentRowId);
startActivity(intent);
}
Moving Act1->Act2 Act2->Act1 never gives me trouble. There I use startActivityForResult(intent, ACTIVITY_EDIT); and I am not sure - could this be the source of my trouble?
I would be grateful if anyone could shed some light on this subject. I am interested in learning some more about this subject.
Thanks,D.
I call this a 2 dimensional problem: two things were responsible for this crash:
1. I used startManagingCursor(mItemCursor); where I shouldn't have.
2. I forgot to initCursorAdapter() (for autocomplete) on onResume()
//#SuppressWarnings("deprecation")
private void initCursorAdapter()
{
mItemCursor = mDbHelper.getCompetitorsCursor("");
startManagingCursor(mItemCursor); //<= this is bad!
mCursorAdapter = new CompetitorAdapter(getApplicationContext(), mItemCursor);
initItemFilter();
}
Now it seems to work fine. I hope so...
Put this it may work for you:
#Override
protected void onRestart() {
// TODO Auto-generated method stub
super.onRestart();
orderCursor.requery();
}
This also works
if (Build.VERSION.SDK_INT < Build.VERSION_CODES.HONEYCOMB) {
startManagingCursor(Cursor);
}
I have a combobox, that I populate from a web service:
public Configure()
{
InitializeComponent();
WebServiceSoapClient ws = new WebServiceSoapClient();
ws.GetTypesCompleted += new EventHandler<GetTypesCompletedEventArgs>(OnGetTypeCompleted);
ws.GetTypesAsync();
}
void OnGetTypeCompleted(object sender, GetTypesCompletedEventArgs e)
{
if (e.Result != null)
{
List<CodeTableItem> source = e.Result.ToList<CodeTableItem>();
lstType.ItemsSource = source;
lstType.SelectedIndex = -1;
}
}
So when I set the ItemSource property, SelectionChanged event gets fired with SelectedIndex = 0, but user hasn't made this selection yet and I need this list to have no selected value, so I'm setting SelectedIndex to -1, as you can see. As a result, SelectionChanged is called twice.
Can I make it be called only when user selects the item?
Thanks!
I'm using Silverlight 3 and VS 2008
Instead, modify your code so that the SelectionChange event handler isn't defined until after the itemssource and selected index are set.
void OnGetTypeCompleted(object sender, GetTypesCompletedEventArgs e)
{
if (e.Result != null)
{
List<CodeTableItem> source = e.Result.ToList<CodeTableItem>();
lstType.ItemsSource = source;
lstType.SelectedIndex = -1;
lstType.SelectionChanged += new SelectionChangedEventHandler(lstType_SelectionChanged);
}
}
In our application we implemented some code that would set a boolean flag based on the Control.LeftMouseButtonUp() event. When this has been set, it would mean that the user has interacted with the field, and so we can handle the SelectionChanged with different behaviour.
Over the development lifetime of our application this approach was essential so that default bindings would trigger our SelectionChanged logic when we didn't want it to.
If you are an MVVM purist, you'll need to expose the VM as a member variable and then set the bool flag in the VM.
HTH,
Mark
I have the following Action Method:
[HandleFtmsError]
public ActionResult PerformanceChart(ChartViewModel chart)
{
var x = 1;
var y = 0;
var z = x/y;
return Json("");
}
where HaneleFtmsError is defined as:
public class HandleFtmsErrorAttribute : System.Web.Mvc.HandleErrorAttribute
{
public override void OnException(ExceptionContext context)
{
base.OnException(context);
if (context.ExceptionHandled)
RaiseErrorSignal(context.Exception);
}
private static void RaiseErrorSignal(Exception e)
{
var context = HttpContext.Current;
ErrorSignal.FromContext(context).Raise(e, context);
}
}
I thought that attribute over the action method would have been executed with a DivideByZero exception, but it's not working. All I'm seeing is the code breaks on the line where I'm doing the division. Am I doing something wrong?
When you say "the code breaks" do you mean it's breaking into the debugger? That's probably just the standard debugger behaviour, which you can change via the Debug menu's "Exceptions..." item. If you hit F5 again - or run without debugging - you may see the behaviour you expect.
MVC isn't preventing the exception from being thrown (which is what the debugger's looking for) - it's just handling the exception by noticing the attribute on the controller and passing the information on appropriately. At the point where the debugger's breaking in, there hasn't been a chance for it to do that yet.
I am writing an Excel 2007 Addin. using VS2008 and .net 3.5, C#.
I catched Microsoft.Office.Interop.Excel.Application's WindowActivate and WindowDeActivate events.
It was surprised to know that WindowActivate and Deactivate only triggers when i switch between two Excel Windows. if i switch to notepad, i expect Deactivate to be triggered, but its not happening. same way from notepad if i switch to excel window, i expect Activate to be triggered but its not happening. It looks like the behaviour indicates windows are MDI-Child windows.
Now what i want to do is get HWnd of Excel's Mainwindow and hook Window Activate and Deactivates using dllimport features.
Can anyone guide to me on this.
Regards
I solved similar problem when writing Excel addin. No dll import is needed. I solved this issue using System.Windows.Forms.NativeWindow class.
At first, I made my own class inherited from NativeWindow class and declared two events Activated and Deactivate in it and finaly overrided WndProc() method to rise these events when message WM_ACTIVATE is passed to the WndProc method. According to "Message" parameter WParm is Excel window activated or deactivated.
public class ExcelWindow: NativeWindow
{
public const int WM_ACTIVATED = 0x0006;
public ExcelWindow():base(){}
//events
public event EventHandler Activated;
public event EventHandler Deactivate;
//catching windows messages
protected override void WndProc(ref Message m)
{
if (m.Msg== WM_ACTIVATED)
{
if (m.WParam.ToInt32() == 1)
{
//raise activated event
if (Activated!=null)
{
Activated(this, new EventArgs());
}
}
else if (m.WParam.ToInt32() == 0)
{
//raise deactivated event
if (Deactivate!=null)
{
Deactivate(this, new EventArgs());
}
}
}
base.WndProc(ref m);
}
}
Then I made in my addin class field "ExcelWindow myExcelWindow" and added following code to OnConnection method of my addin:
ExcelWindow myExcelWindow;
void Extensibility.IDTExtensibility2.OnConnection(object application, Extensibility.ext_ConnectMode ConnectMode, object AddInInst, ref Array custom)
{
excel = application as Excel.Application;
myExcelWindow = new ExcelWindow();
myExcelWindow.AssignHandle(new IntPtr(excel.Hwnd));
myExcelWindow.Activated += new EventHandler(myExcelWindow_Activated);
myExcelWindow.Deactivate += new EventHandler(myExcelWindow_Deactivate);
//addin code here
}
void myExcelWindow_Activated(object sender, EventArgs e)
{
//do some stuff here
}
void myExcelWindow_Deactivate(object sender, EventArgs e)
{
//do some stuff here
}
I hope this will help you.
Finally I found one solution..that works only Activate/Deactivate.
This is not the perfect way to do it. But I did not find any good alternative.
This method uses polling. I have to call following function in each 10 ms interval to check focus in/out.
public static bool ApplicationIsActivated()
{
var activatedHandle = GetForegroundWindow();
if (activatedHandle == IntPtr.Zero)
{
return false; // No window is currently activated
}
var procId = Process.GetCurrentProcess().Id;
int activeProcId;
GetWindowThreadProcessId(activatedHandle, out activeProcId);
return activeProcId == procId;
}