I want to add a List to ComboBox through Dispatcher.BeginInvoke. But when I try to put it in a loop, only last value is loading.
private void LoadToComboBox(List<string> msg)
{
for (int i = 0; i < msg.Count; i++)
{
this.Dispatcher.BeginInvoke(() => cmbListItems.Items.Add(msg[i]));
}
}
The Dispatcher.BeginInvoke() is an asynchronous call. What is happening is that by the time you are calling your cmbListItems.Items.Add() function, it is already set to msg.Count.
Try something like this:
private void LoadToComboBox(List<string> msg)
{
this.Dispatcher.BeginInvoke(() =>
{
for (int i = 0; i < msg.Count; i++) {
cmbListItems.Items.Add(msg[i]);
}
});
}
Related
Im trying to add some dummy content into my database. I have a sample object called "obj", and I'm using a for loop to insert data like the code below:
public async Task<Post> Add(Post obj)
{
if (db != null)
{
obj.Id = 0;
for (int i = 0; i < 100; i++)
{
await db.Post.AddAsync(obj);
}
await db.SaveChangesAsync();
return obj;
}
return null;
}
However, it does add only 1 record into database, could you please explain what's wrong here?
Can you create object of post inside the loop and try again?
for (int i = 0; i < 100; i++)
{
Post obj = new Post();
await db.Post.AddAsync(obj);
}
If you run the below commands before calling saved changes you can see what changes EF Core has queued up.
var post = new Post();
for (int i = 0; i < 10; i++)
{
await db.Posts.AddAsync(dev);
}
db.ChangeTracker.DetectChanges();
Debug.WriteLine(db.ChangeTracker.DebugView.LongView);
await db.SaveChangesAsync();
This will write to Debug that one post is currently being tracked.
for (int i = 0; i < 10; i++)
{
var post = new Post();
await db.Posts.AddAsync(dev);
}
db.ChangeTracker.DetectChanges();
Debug.WriteLine(db.ChangeTracker.DebugView.LongView);
await db.SaveChangesAsync();
This will right to the Debug window the 10 posts are currently being tracked.
In your code when you AddAsync(obj), obj isn't a new object and EF Core is already tracking obj.
Moving Post obj = new Post() into the loop creates a new object for EF Core to track. If these objects aren't being added to the DB my guess would be that they don't meet a requirement for the Post model.
Either way playing around with
db.ChangeTracker.DetectChanges();
Debug.WriteLine(db.ChangeTracker.DebugView.LongView);
should help you be able to track down exactly what's going on.
I do hope you find this information helpful :)
You can try to use AddRange.
public async Task<Post> Add(Post obj)
{
if (db != null)
{
List<Post>=new List<Post>();
obj.Id = 0;
for (int i = 0; i < 100; i++)
{
l.Add(obj);
}
await db.Post.AddRangeAsync(l);
await db.SaveChangesAsync();
return obj;
}
return null;
}
My main process:
public void quoteStartReceive()
{
Thread thdWrite = new Thread(new ThreadStart(DoParseGUIDisplay));
thdWrite.IsBackground = true;
thdWrite.Start();
}
My thread function:
void DoParseGUIDisplay()
{
for (int i = 0; i < 1024; i++)
{
if (myQueue.Count > 0)
{
string strOut = myQueue.Dequeue().ToString();
Tick tick = new Tick(strOut);
if (tick.m_last != "")
{
string msg = "Update Text";
if (this.textBox1.InvokeRequired)
{
this.textBox1.BeginInvoke((MethosInvoker)delegate () {this.textBox1.Text = msg; };
}
else
{
this.textBox1.Text = msg;
}
}
}
}
}
No matter I tried to use Invoke() or BeginInvoke(), I cannot update the text in textBox1.
I also tried another way:
public delegate void UpdateTextCallback(string text);
It still cannot help me to update my textBox1.
Help me to find out what stuff I missed. Thanks.
put an argument before the thread:
Application.DoEvents();
and it should be put after the m_last was updated.
In my program I use Roslyn and I need to replace a node with a new node. For example, if I have code like
public void Foo()
{
for(var i = 0; i < 5; i++)
Console.WriteLine("");
}
and I want to insert brackes for for statement, I get
public void Foo()
{
for(var i = 0; i < 5; i++)
{
Console.WriteLine("");
}
}
I tried to use NormalizeWhitespace, but if I use it on for statement, I get
public void Foo()
{
for(var i = 0; i < 5; i++)
{
Console.WriteLine("");
}
}
However, I'd like to have for statement formatted correctly. Any hints how to do it?
EDIT:
I solved it by using:
var blockSyntax = SyntaxFactory.Block(
SyntaxFactory.Token(SyntaxKind.OpenBraceToken).WithLeadingTrivia(forStatementSyntax.GetLeadingTrivia()).WithTrailingTrivia(forStatementSyntax.GetTrailingTrivia()),
syntaxNodes,
SyntaxFactory.Token(SyntaxKind.CloseBraceToken).WithLeadingTrivia(forStatementSyntax.GetLeadingTrivia()).WithTrailingTrivia(forStatementSyntax.GetTrailingTrivia())
);
However, the answer from Sam is also correct.
You need to use .WithAdditionalAnnotations(Formatter.Annotation), but only on the specific element you want to format. Here's an example from the NullParameterCheckRefactoring project.
IfStatementSyntax nullCheckIfStatement = SyntaxFactory.IfStatement(
SyntaxFactory.Token(SyntaxKind.IfKeyword),
SyntaxFactory.Token(SyntaxKind.OpenParenToken),
binaryExpression,
SyntaxFactory.Token(SyntaxKind.CloseParenToken),
syntaxBlock, null).WithAdditionalAnnotations(Formatter.Annotation, Simplifier.Annotation);
I am trying to read in a text file for a maze program. The input is something like:
10 10
OO+E+OO+++
O++O+O+OOO
OOOOOO+O+O
+++++O++OO
OOO+OOO+O+
O+O+O+++O+
O+O+OOO+OO
++O+++O++O
O+OOOOO++O
O+O++O+OOO
When the user click on the open button, this opens a open file dialog box
{
openFileDialog1->InitialDirectory = "C:\Desktop;";
openFileDialog1->Filter = "Maze files (*.DAT)|*.DAT";
if (openFileDialog1->ShowDialog() == ::DialogResult::OK)
{
char filename[1024];
for (int i = 0; i < openFileDialog1->FileName->Length; i++)
{
filename[i] = openFileDialog1->FileName[i];
}
ifstream ifs;
ifs.open(filename); // NULL terminate this
maze = new Maze( panel1, ifs);
ifs.close();
}
}
the following is the maze constructor
Maze::Maze( Panel ^ drawingPanel, ifstream & ifs )
{
try
{
valid = false;
ifs >> width >> height;
int temp = width;
drawingPanel->Size.Width = width;
drawingPanel->Size.Height = height;
for (int i = 0; i < height; i++) // height is always nothing
for (int j = 0; j < width; j++)
{
if (orig[j][i] == DEADEND ||
orig[j][i] == OPEN ||
orig[j][i] == EXIT )
ifs >> orig[j][i]; // NULLS????
else
throw 'D'; // i had to throw something....so i threw the D /* make a slit class and throw the D there? slit.fill(D); */
}
// this should be last
panel = drawingPanel;
valid = true;
}
catch (...)
{
valid = false;
MessageBox::Show( "Not a proper maze file!" );
}
}
when the program runs: ifs >> width >> height width and height do not get set correctly.
I have searched this site for this problem and have not been able to find anything that has helped. Sorry for my inexperience, any help is greatly appreciated.
You'e program very ugly : don't know if you're programming in C or C++ or C++/CLI, or try to mix the 3...
Because you use Windows Form projet, i will give you a .Net solution for read a file, it's not the better solution but this does not mix things.
First for read the file, on a first window :
private: System::Void button1_Click(System::Object^ sender, System::EventArgs^ e)
{
openFileDialog1->Filter = "Maze Files (*.dat) | *.dat";
if (openFileDialog1->ShowDialog() == ::DialogResult::OK)
{
String ^fileName = openFileDialog1->FileName;
IO::StreamReader ^myMazeFile = gcnew IO::StreamReader(fileName);
String ^content = myMazeFile->ReadToEnd();
richTextBox1->Text = content;
myMazeFile->Close();
// display button for open second form wich draw maze
button2->Visible = true;
}
}
now we have our file content, so we pass it to a second form who will draw the maze :
private: System::Void button2_Click(System::Object^ sender, System::EventArgs^ e)
{
String ^content = richTextBox1->Text;
Maze ^frm = gcnew Maze(content);
frm->Show();
}
Second window, create overload constructor :
Maze(String ^contentMap)
{
InitializeComponent();
String ^dimension = getWords(contentMap, 2);
array<String ^> ^coordsString = dimension->Split(gcnew array<Char> {' '});
m_width = Convert::ToInt32(coordsString[0]);
m_height = Convert::ToInt32(coordsString[1]);
panel1->Width = m_width;
panel1->Height = m_height;
}
getWords method :
String ^getWords(String ^input, int numWords)
{
try
{
int words = numWords;
for (int i = 0; i < input->Length; ++i)
{
if (input[i] == ' ' ||input[i] == '\n')
words--;
if (words == 0)
{
return input->Substring(0, i);
}
}
}
catch (Exception ^ex)
{
// ...
}
return String::Empty;
}
You have your dimension in full .Net (private member m_width and m_height).
This method needs to sort and array and I am close with the following code but what it does is puts the list forwards to backwards i.e. if the list was "5, 4, 3" this would change it to "3, 4, 5". This is because after the if statement completes it goes back to the for and once it is finished the for it sets lowest back to 1000. How do I make it not set it back to 1000 each time?
public void sortList()
{
for(int i=0; i<myList.size(); i++)
{
int lowest = 1000;
if(myList.get(i)<lowest)
{
myList.add(0, myList.get(i));
myList.remove(i+1);
}
}
}
This :
public void sortList() {
int lowest = 1000;
for(int i=0; i<myList.size(); i++)
{
if(myList.get(i)<lowest)
{
myList.add(0, myList.get(i));
myList.remove(i+1);
}
}
}
You simply declare lowest outside of the loop, and update it in the loop.
With the example you gave, I would move the 'lowest' declaration out of the for loop, like so:
int lowest = 1000;
for(int i=0; i<myList.size(); i++)
{
if(myList.get(i)<lowest)
{
myList.add(0, myList.get(i));
myList.remove(i+1);
}
}
That way it's not reset to 1000 with each for loop. You can then update it within the loop as needed as you would any other numeric variable.