// Xaml
<Grid x:Name="_Grid" Width="926" Margin="603,140,391,55">
</Grid>
// Code behind
Button hello = new Button();
hello.Content = "Hello World";
_Grid.Children.Add(hello);
Trying to inject hello button into _Grid but the following error get shown:
System.NullReferenceException: 'Object reference not set to an instance of an object.'
_Grid was null.
I can reproduce your issue when executing these code before calling InitializeComponent() method. InitializeComponent() method is automatically created and managed by XAML designer and it defines everything you see on the Window. Everything done on the window using designers generates code. Every single control added and property set will generate code and that code goes into InitializeComponent() method.
Therefore, if you inject this button before InitializeComponent() method, the Grid don’t generate, it is null. so that it reported the NullReferenceException when you use this grid. Please operate these code after calling InitializeComponent() method like the following.
public MainPage()
{
this.InitializeComponent();
Button helloBtn = new Button();
helloBtn.Content = "Hello World";
_Grid.Children.Add(helloBtn);
}
Related
I'm using an IntelliJ GUI form to create a toolwindow as part of an IntelliJ plugin. This is some code in the class bound to the form:
private JButton checkNifi;
NifiToolWindow(ToolWindow toolWindow) {
checkNifi.addActionListener(e -> toolWindow.hide(null));
}
I understand that when this action listener is added the button is still null and this is the issue, however even if I do checkNifi = new JButton("Some text");, the null pointer instead gets thrown on this line.
I should add I also have a ToolWindowFactory class which looks like this:
#Override
public void createToolWindowContent(#NotNull Project project, #NotNull com.intellij.openapi.wm.ToolWindow toolWindow) {
NifiToolWindow nifiToolWindow = new NifiToolWindow(toolWindow);
ContentFactory contentFactory = new ContentFactoryImpl();
Content content = contentFactory.createContent(nifiToolWindow.getContent(), "", false);
toolWindow.getContentManager().addContent(content);
}
This is taken from the example here https://github.com/JetBrains/intellij-sdk-docs/tree/master/code_samples/tool_window/src/myToolWindow
Any help or ideas would be great.
I found the solution, I had create custom box ticked in the gui designer, but an empty createGuiComponents() method. Therefore it was null.
I am trying to implement 2 AutoCompleteTextView. First one holds the value, on click of one of them will populate the data in second AutoCompleteTextView, all works and data gets loaded correctly however when I try to call notifyDataSetChanged on the second adapter which populates the second field that does not get changed.
I also wrote that piece of code inside a Handler too, however that does not seems to work either.
branchAdapter = new ArrayAdapter(this,android.R.layout.simple_list_item_1,branchNames);
et7.setAdapter(branchAdapter);//et7 is the AutoCompleteTextView //branchname is the ArrayList
in some method I clean up the ArrayList and add the new data into it and then call notifyDataSetChanged like below
Handler handler = new Handler(Looper.getMainLooper());
handler.post(new Runnable() {
#Override
public void run() {
branchAdapter.notifyDataSetChanged();
}
});
Which is not updating the list. What should be the correct way here to update data?
#Saty, I guess i am a little late to the party. I am answering, keeping in mind that, it may help somebody in future.
Cleanup the adapter as well using branchAdapter.clear() method. Then add new items to the adapter using branchAdapter.addAll(String... items) method. Now, call branchAdapter.notifyDataSetChanged() method. This will work.
Try resetting listview instead.
ListView lv = (ListView)findViewById(R.id.lv);
ArrayAdapter adapter = new ArrayAdapter(/*with all parameters*/);
lv.setAdapter(adapter);
I'm using Smart Client Software Factory 2008. In the module controller, I have code that creates a new child controller only if it hasn't been created, by doing something like the following:
Dim key = "Item-" + item.ID.ToString()
Dim childWorkItem = Me.WorkItem.WorkItems.Get(Of ControlledWorkItem(Of ItemWorkItemController))(key)
If childWorkItem Is Nothing Then
childWorkItem = Me.WorkItem.WorkItems.AddNew(Of ControlledWorkItem(Of ItemWorkItemController))(key)
Else
childWorkItem.Activate()
End If
Multiple items reuse the same key, so when that action is triggered, it shows the tab instead of creating a new instance of it. This works great.
However, there is one drawback. Once activated, I need to run a check within that item's presenter. So I need to call a method on the presenter. Is there a way to invoka a method on the presenter, or is there an event that runs on the view when the work item is activated? I'm not sure how to make that happen?
Thanks.
If you are using a Smart Part as your View you should be able to accomplish this using the IWorkspace.SmartPartActivated event.
This is how I have it setup in my project. I apologize, my code is all in C# but you should be able to apply it in VB relatively easily.
The WorkItemController class has the Activate method setup like this
ISmartPartView _smartPartView
public void Activate()
{
IWorkspace contentWorkspace = this.WorkItem.Workspaces[WorkspaceNames.ShellContentWorkspace];
contentWorkspace.Activate(_smartPartView);
WorkItem.Activate();
}
In the ISmartPartView Presenter class you should be able to create a handler for the SmartPartActivated event like this:
IWorkspace contentWorkspace = this.WorkItem.Workspaces[WorkspaceNames.ShellContentWorkspace];
contentWorkspace.SmartPartActivated += workSpaceSmartPart_ActivatedHandler;
In the workSpaceSmartPart_ActivatedHandler event handler, you can check the SmartPart being activated and if its your ISmartPartView class you can run the desired code.
I'm using a Silverlight 4 dataform and attempting to use the inbuilt add button to create a new item in my collection. It works fine except that I have a number of properties that need to be set behind the scenes. I've tried hooking into the likely looking events such as AddingNewItem but the new item is readonly at that point and I can't set the properties.
Is there a trick to add new items using the Silverlight 4 dataform?
Finally stumbled on the way to do it after much searching and trial and error.
The rather counter-intuitive place to set the properties on a newly created dataform item is in the EditEnding event handler. The dataform Mode property is readonly in the AddingNewItem handler but is equal to AddNew in the EditEnding handler.
My EditEnding handler code is along the lines of:
private void EditEnding(object sender, DataFormEditEndingEventArgs e)
{
if (myDataForm.Mode == DataFormMode.AddNew)
{
MyItem item = myDataForm.CurrentItem as MyItem;
item.ID = Guid.NewGuid().ToString();
}
}
I am trying to retrieve strings from the database and add it as content to the controls on my page before it loads(somewhat like a custom localization). I retrieve my strings from the database uing ria services as follows:
**
Web.DomainService1 context = new Web.DomainService1();
LoadOperation<Web.LocalizationTab>LoadOp=context.Load(context.GetLocalizationTabsQuery(currentCulture, moduleName));
Dictionary<string, string> localizationDictonary = new Dictionary<string, string>();
List<Web.LocalizationTab> localList = new List<Web.LocalizationTab>();
LoadOp.Completed += (s, e) =>
{
localList = LoadOp.Entities.ToList<Web.LocalizationTab>();
//System.Windows.MessageBox.Show(localList.Count.ToString());
foreach (Web.LocalizationTab item in localList)
{
// var control = this.FindName(item.Control_ID.ToString());
if (!localizationDictonary.ContainsKey(item.Control_ID))
{
localizationDictonary.Add(item.Control_ID, item.Control_Text);
}
}
};**
This piece of code is in a separate class called utilities.cs.
now in my Mainpage.xaml.cs i need to get this dictionary with values and then set the controls with the strings from the dictionary.
my problem is that when i do the following in the constructor of Mainpage.xaml.cs:
utilities.getDict(ModuleName);
button1.Content = localizationDictonary["button1"].ToString();
i get an exception as the dictionary doesnt contain values at that point of time.. The load completed event of getting data from the database gets fired only after my constructor is exited. now how do i go about setting my controls automatically in this particular scenario??
Try loading your dictionary in the Silverlight Application class StartUp event. This should ensure that your Dictionary is loaded (and could be placed in the Application Resources for retrieval elsewhere in your application).
You'll need to wait for the GetLocalizationTabsQuery to complete before instantiating your MainPage. In your App.xaml.cs file, you can start the query, add a query completed handler, and only create the MainPage when the query completed handler gets called.