How to fix an instance when trying to access a button of another winform?
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hello i have this code here (Owner as ReadBarCodeInMenu).btnContainerInquiry.Enabled = true; it keeps me throwing an instance whenever i tried to access a button of another page it tried this code in a test 2 forms and it works perfectly fine but when i put it in system i gave me an error.Please help me
edit:
form ReadBarCodeInMenu
private void btnContainerInquiry_Click(object sender, EventArgs e)
{
inquiry.Owner = this;
btnContainerInquiry.Enabled = false;
}
form ContainerInquiry
private void logoutBtn_Click(object sender, EventArgs e)
{
(Owner as ReadBarCodeInMenu).btnContainerInquiry.Enabled = true;
error// {"Object reference not set to an instance of an object."}
close.
}
this is how i access the bottom of an another form if i do this in new 2 form it works with no error.
c# winforms
asked Nov 11 at 23:12
Red
96
add a comment |
up vote
0
down vote
favorite
hello i have this code here (Owner as ReadBarCodeInMenu).btnContainerInquiry.Enabled = true; it keeps me throwing an instance whenever i tried to access a button of another page it tried this code in a test 2 forms and it works perfectly fine but when i put it in system i gave me an error.Please help me
edit:
form ReadBarCodeInMenu
private void btnContainerInquiry_Click(object sender, EventArgs e)
{
inquiry.Owner = this;
btnContainerInquiry.Enabled = false;
}
form ContainerInquiry
private void logoutBtn_Click(object sender, EventArgs e)
{
(Owner as ReadBarCodeInMenu).btnContainerInquiry.Enabled = true;
error// {"Object reference not set to an instance of an object."}
close.
}
this is how i access the bottom of an another form if i do this in new 2 form it works with no error.
c# winforms
asked Nov 11 at 23:12
Red
96
Please show your code showing the problem, we can't guess.
– Poul Bak
Nov 11 at 23:25
my error is an instance (Owner as ReadBarCodeInMenu).btnContainerInquiry.Enabled = true; {"Object reference not set to an instance of an object."}
– Red
Nov 11 at 23:48
Try to start debugging and step through you code. (Either 'Owner' is null or btnContainer.Inquiry is null)
– Poul Bak
Nov 11 at 23:50
BecauseOwneris probably not aReadBarCodeInMenu. "Owner" is strange anyway. What do you mean by another page? You need a reference to the form containing button.
– Olivier Jacot-Descombes
Nov 11 at 23:53
add a comment |
up vote
0
down vote
favorite
up vote
0
down vote
favorite
hello i have this code here (Owner as ReadBarCodeInMenu).btnContainerInquiry.Enabled = true; it keeps me throwing an instance whenever i tried to access a button of another page it tried this code in a test 2 forms and it works perfectly fine but when i put it in system i gave me an error.Please help me
edit:
form ReadBarCodeInMenu
private void btnContainerInquiry_Click(object sender, EventArgs e)
{
inquiry.Owner = this;
btnContainerInquiry.Enabled = false;
}
form ContainerInquiry
private void logoutBtn_Click(object sender, EventArgs e)
{
(Owner as ReadBarCodeInMenu).btnContainerInquiry.Enabled = true;
error// {"Object reference not set to an instance of an object."}
close.
}
this is how i access the bottom of an another form if i do this in new 2 form it works with no error.
c# winforms
asked Nov 11 at 23:12
Red
96
hello i have this code here (Owner as ReadBarCodeInMenu).btnContainerInquiry.Enabled = true; it keeps me throwing an instance whenever i tried to access a button of another page it tried this code in a test 2 forms and it works perfectly fine but when i put it in system i gave me an error.Please help me
edit:
form ReadBarCodeInMenu
private void btnContainerInquiry_Click(object sender, EventArgs e)
{
inquiry.Owner = this;
btnContainerInquiry.Enabled = false;
}
form ContainerInquiry
private void logoutBtn_Click(object sender, EventArgs e)
{
(Owner as ReadBarCodeInMenu).btnContainerInquiry.Enabled = true;
error// {"Object reference not set to an instance of an object."}
close.
}
this is how i access the bottom of an another form if i do this in new 2 form it works with no error.
c# winforms
c# winforms
asked Nov 11 at 23:12
Red
96
asked Nov 11 at 23:12
Red
96
edited Nov 11 at 23:56
asked Nov 11 at 23:12
Red
96
asked Nov 11 at 23:12
Red
96
asked Nov 11 at 23:12
Red
96
96
Please show your code showing the problem, we can't guess.
– Poul Bak
Nov 11 at 23:25
my error is an instance (Owner as ReadBarCodeInMenu).btnContainerInquiry.Enabled = true; {"Object reference not set to an instance of an object."}
– Red
Nov 11 at 23:48
Try to start debugging and step through you code. (Either 'Owner' is null or btnContainer.Inquiry is null)
– Poul Bak
Nov 11 at 23:50
BecauseOwneris probably not aReadBarCodeInMenu. "Owner" is strange anyway. What do you mean by another page? You need a reference to the form containing button.
– Olivier Jacot-Descombes
Nov 11 at 23:53
add a comment |
Please show your code showing the problem, we can't guess.
– Poul Bak
Nov 11 at 23:25
my error is an instance (Owner as ReadBarCodeInMenu).btnContainerInquiry.Enabled = true; {"Object reference not set to an instance of an object."}
– Red
Nov 11 at 23:48
Try to start debugging and step through you code. (Either 'Owner' is null or btnContainer.Inquiry is null)
– Poul Bak
Nov 11 at 23:50
BecauseOwneris probably not aReadBarCodeInMenu. "Owner" is strange anyway. What do you mean by another page? You need a reference to the form containing button.
– Olivier Jacot-Descombes
Nov 11 at 23:53
Please show your code showing the problem, we can't guess.
– Poul Bak
Nov 11 at 23:25
Please show your code showing the problem, we can't guess.
– Poul Bak
Nov 11 at 23:25
my error is an instance (Owner as ReadBarCodeInMenu).btnContainerInquiry.Enabled = true; {"Object reference not set to an instance of an object."}
– Red
Nov 11 at 23:48
my error is an instance (Owner as ReadBarCodeInMenu).btnContainerInquiry.Enabled = true; {"Object reference not set to an instance of an object."}
– Red
Nov 11 at 23:48
Try to start debugging and step through you code. (Either 'Owner' is null or btnContainer.Inquiry is null)
– Poul Bak
Nov 11 at 23:50
Try to start debugging and step through you code. (Either 'Owner' is null or btnContainer.Inquiry is null)
– Poul Bak
Nov 11 at 23:50
Because
Owner is probably not a ReadBarCodeInMenu. "Owner" is strange anyway. What do you mean by another page? You need a reference to the form containing button.– Olivier Jacot-Descombes
Nov 11 at 23:53
Because
Owner is probably not a ReadBarCodeInMenu. "Owner" is strange anyway. What do you mean by another page? You need a reference to the form containing button.– Olivier Jacot-Descombes
Nov 11 at 23:53
add a comment |
1 Answer
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0
down vote
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Assuming that you open form ContainerInquiry from withing form ReadBarCodeInMenu, you can do the following. In form ContainerInquiry, add a parameter to the constructor, accepting a reference to the first form
private ReadBarCodeInMenu _readBarCodeInMenu;
public ContainerInquiry(ReadBarCodeInMenu readBarCodeInMenu)
{
InitializeComponent();
_readBarCodeInMenu = readBarCodeInMenu;
}
private void logoutBtn_Click(object sender, EventArgs e)
{
_readBarCodeInMenu.btnContainerInquiry.Enabled = true;
}
Also, change the accessibility of btnContainerInquiry from private to internal (or public).
Then in form ReadBarCodeInMenu
// Pass a reference of ReadBarCodeInMenu to ContainerInquiry.
var frm = new ContainerInquiry(this);
...
You cannot access the UI from another thread than the UI thread. If try to do so, you are getting the exception
Cross-thread operation not valid: Control 'btnContainerInquiry' accessed from a thread other than the thread it was created on.
In this case you must invoke the control or form you are accessing. This mechanism passes a delegate to the right thread and executes it there.
var btn = _readBarCodeInMenu.btnContainerInquiry;
if (btn.InvokeRequired) {
btn.Invoke(new Action(() => btn.Enabled = true));
} else {
btn.Enabled = true;
}
You could also create an extension method that automates this process as shown here: https://stackoverflow.com/a/12179408/880990
answered Nov 12 at 0:01
Olivier Jacot-Descombes
65.1k885136
it works but i need to access to another form in order to close it or else it give me an error of {"Cross-thread operation not valid: Control 'btnContainerInquiry' accessed from a thread other than the thread it was created on."} example if i open form 1 and click the button for form2 i can't close the form to i need to press the button for form3 in form 1 then close the form 2.
– Red
Nov 12 at 0:19
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
0
down vote
accepted
Assuming that you open form ContainerInquiry from withing form ReadBarCodeInMenu, you can do the following. In form ContainerInquiry, add a parameter to the constructor, accepting a reference to the first form
private ReadBarCodeInMenu _readBarCodeInMenu;
public ContainerInquiry(ReadBarCodeInMenu readBarCodeInMenu)
{
InitializeComponent();
_readBarCodeInMenu = readBarCodeInMenu;
}
private void logoutBtn_Click(object sender, EventArgs e)
{
_readBarCodeInMenu.btnContainerInquiry.Enabled = true;
}
Also, change the accessibility of btnContainerInquiry from private to internal (or public).
Then in form ReadBarCodeInMenu
// Pass a reference of ReadBarCodeInMenu to ContainerInquiry.
var frm = new ContainerInquiry(this);
...
You cannot access the UI from another thread than the UI thread. If try to do so, you are getting the exception
Cross-thread operation not valid: Control 'btnContainerInquiry' accessed from a thread other than the thread it was created on.
In this case you must invoke the control or form you are accessing. This mechanism passes a delegate to the right thread and executes it there.
var btn = _readBarCodeInMenu.btnContainerInquiry;
if (btn.InvokeRequired) {
btn.Invoke(new Action(() => btn.Enabled = true));
} else {
btn.Enabled = true;
}
You could also create an extension method that automates this process as shown here: https://stackoverflow.com/a/12179408/880990
answered Nov 12 at 0:01
Olivier Jacot-Descombes
65.1k885136
it works but i need to access to another form in order to close it or else it give me an error of {"Cross-thread operation not valid: Control 'btnContainerInquiry' accessed from a thread other than the thread it was created on."} example if i open form 1 and click the button for form2 i can't close the form to i need to press the button for form3 in form 1 then close the form 2.
– Red
Nov 12 at 0:19
add a comment |
up vote
0
down vote
accepted
Assuming that you open form ContainerInquiry from withing form ReadBarCodeInMenu, you can do the following. In form ContainerInquiry, add a parameter to the constructor, accepting a reference to the first form
private ReadBarCodeInMenu _readBarCodeInMenu;
public ContainerInquiry(ReadBarCodeInMenu readBarCodeInMenu)
{
InitializeComponent();
_readBarCodeInMenu = readBarCodeInMenu;
}
private void logoutBtn_Click(object sender, EventArgs e)
{
_readBarCodeInMenu.btnContainerInquiry.Enabled = true;
}
Also, change the accessibility of btnContainerInquiry from private to internal (or public).
Then in form ReadBarCodeInMenu
// Pass a reference of ReadBarCodeInMenu to ContainerInquiry.
var frm = new ContainerInquiry(this);
...
You cannot access the UI from another thread than the UI thread. If try to do so, you are getting the exception
Cross-thread operation not valid: Control 'btnContainerInquiry' accessed from a thread other than the thread it was created on.
In this case you must invoke the control or form you are accessing. This mechanism passes a delegate to the right thread and executes it there.
var btn = _readBarCodeInMenu.btnContainerInquiry;
if (btn.InvokeRequired) {
btn.Invoke(new Action(() => btn.Enabled = true));
} else {
btn.Enabled = true;
}
You could also create an extension method that automates this process as shown here: https://stackoverflow.com/a/12179408/880990
answered Nov 12 at 0:01
Olivier Jacot-Descombes
65.1k885136
it works but i need to access to another form in order to close it or else it give me an error of {"Cross-thread operation not valid: Control 'btnContainerInquiry' accessed from a thread other than the thread it was created on."} example if i open form 1 and click the button for form2 i can't close the form to i need to press the button for form3 in form 1 then close the form 2.
– Red
Nov 12 at 0:19
add a comment |
up vote
0
down vote
accepted
up vote
0
down vote
accepted
Assuming that you open form ContainerInquiry from withing form ReadBarCodeInMenu, you can do the following. In form ContainerInquiry, add a parameter to the constructor, accepting a reference to the first form
private ReadBarCodeInMenu _readBarCodeInMenu;
public ContainerInquiry(ReadBarCodeInMenu readBarCodeInMenu)
{
InitializeComponent();
_readBarCodeInMenu = readBarCodeInMenu;
}
private void logoutBtn_Click(object sender, EventArgs e)
{
_readBarCodeInMenu.btnContainerInquiry.Enabled = true;
}
Also, change the accessibility of btnContainerInquiry from private to internal (or public).
Then in form ReadBarCodeInMenu
// Pass a reference of ReadBarCodeInMenu to ContainerInquiry.
var frm = new ContainerInquiry(this);
...
You cannot access the UI from another thread than the UI thread. If try to do so, you are getting the exception
Cross-thread operation not valid: Control 'btnContainerInquiry' accessed from a thread other than the thread it was created on.
In this case you must invoke the control or form you are accessing. This mechanism passes a delegate to the right thread and executes it there.
var btn = _readBarCodeInMenu.btnContainerInquiry;
if (btn.InvokeRequired) {
btn.Invoke(new Action(() => btn.Enabled = true));
} else {
btn.Enabled = true;
}
You could also create an extension method that automates this process as shown here: https://stackoverflow.com/a/12179408/880990
answered Nov 12 at 0:01
Olivier Jacot-Descombes
65.1k885136
Assuming that you open form ContainerInquiry from withing form ReadBarCodeInMenu, you can do the following. In form ContainerInquiry, add a parameter to the constructor, accepting a reference to the first form
private ReadBarCodeInMenu _readBarCodeInMenu;
public ContainerInquiry(ReadBarCodeInMenu readBarCodeInMenu)
{
InitializeComponent();
_readBarCodeInMenu = readBarCodeInMenu;
}
private void logoutBtn_Click(object sender, EventArgs e)
{
_readBarCodeInMenu.btnContainerInquiry.Enabled = true;
}
Also, change the accessibility of btnContainerInquiry from private to internal (or public).
Then in form ReadBarCodeInMenu
// Pass a reference of ReadBarCodeInMenu to ContainerInquiry.
var frm = new ContainerInquiry(this);
...
You cannot access the UI from another thread than the UI thread. If try to do so, you are getting the exception
Cross-thread operation not valid: Control 'btnContainerInquiry' accessed from a thread other than the thread it was created on.
In this case you must invoke the control or form you are accessing. This mechanism passes a delegate to the right thread and executes it there.
var btn = _readBarCodeInMenu.btnContainerInquiry;
if (btn.InvokeRequired) {
btn.Invoke(new Action(() => btn.Enabled = true));
} else {
btn.Enabled = true;
}
You could also create an extension method that automates this process as shown here: https://stackoverflow.com/a/12179408/880990
answered Nov 12 at 0:01
Olivier Jacot-Descombes
65.1k885136
edited Nov 12 at 13:00
answered Nov 12 at 0:01
Olivier Jacot-Descombes
65.1k885136
answered Nov 12 at 0:01
Olivier Jacot-Descombes
65.1k885136
answered Nov 12 at 0:01
Olivier Jacot-Descombes
65.1k885136
65.1k885136
it works but i need to access to another form in order to close it or else it give me an error of {"Cross-thread operation not valid: Control 'btnContainerInquiry' accessed from a thread other than the thread it was created on."} example if i open form 1 and click the button for form2 i can't close the form to i need to press the button for form3 in form 1 then close the form 2.
– Red
Nov 12 at 0:19
add a comment |
it works but i need to access to another form in order to close it or else it give me an error of {"Cross-thread operation not valid: Control 'btnContainerInquiry' accessed from a thread other than the thread it was created on."} example if i open form 1 and click the button for form2 i can't close the form to i need to press the button for form3 in form 1 then close the form 2.
– Red
Nov 12 at 0:19
it works but i need to access to another form in order to close it or else it give me an error of {"Cross-thread operation not valid: Control 'btnContainerInquiry' accessed from a thread other than the thread it was created on."} example if i open form 1 and click the button for form2 i can't close the form to i need to press the button for form3 in form 1 then close the form 2.
– Red
Nov 12 at 0:19
it works but i need to access to another form in order to close it or else it give me an error of {"Cross-thread operation not valid: Control 'btnContainerInquiry' accessed from a thread other than the thread it was created on."} example if i open form 1 and click the button for form2 i can't close the form to i need to press the button for form3 in form 1 then close the form 2.
– Red
Nov 12 at 0:19
add a comment |
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Please show your code showing the problem, we can't guess.
– Poul Bak
Nov 11 at 23:25
my error is an instance (Owner as ReadBarCodeInMenu).btnContainerInquiry.Enabled = true; {"Object reference not set to an instance of an object."}
– Red
Nov 11 at 23:48
Try to start debugging and step through you code. (Either 'Owner' is null or btnContainer.Inquiry is null)
– Poul Bak
Nov 11 at 23:50
Because
Owneris probably not aReadBarCodeInMenu. "Owner" is strange anyway. What do you mean by another page? You need a reference to the form containing button.– Olivier Jacot-Descombes
Nov 11 at 23:53