The “Object reference not set to an instance of an object” is a very famous error in C# that appears when you get a NullReferenceException. This occurs when you try to access a property or method of an object that points to a null value. They can be fixed using Null conditional operators and handled using try-catch blocks. Show
In this post, we will learn more about the error and the ways to fix it. What is “NullReferenceException: Object reference not set to an instance of an object” error?As mentioned earlier, the NullReferenceException indicates that your code is trying to work with an object that has a null value as its reference. This means that the reference object has not been initialized. This is a runtime exception that can be caught using a try-catch block. Example code try { string a = null; a.ToString(); } catch (NullReferenceException e) { //Code to do something with e }How to fix this error?You can fix this error by using the following methods:
1) Using Null conditional operatorsThis method is easier than using an if-else condition to check whether the variable value is null. Look at this example, int? length = customers?.Length; // this will return null if customers is null, instead of throwing the exception2) Using the Null Coalescing operatorThis operator looks like “??” and provides a default value to variables that have a null value. It is compatible with all nullable datatypes. Example 3) Using nullable datatypes in C#All reference types in C# can have a null value. But some data types such as int and Boolean cannot take null values unless they are explicitly defined. This is done by using Nullable data types. For example, static int Add(string roll_numbers) { return roll_numbers.Split(","); // This code might throw a NullReferenceException as roll_numbers variable can be null }Correct code static int Add(string? roll_numbers) // As roll_numbers argument can now be null, the NullReferenceException can be avoided { return roll_numbers.Split(","); }The best way to avoid the "NullReferenceException: Object reference not set to an instance of an object”error is to check the values of all variables while coding. You can also use a simple if-else statement to check for null values, such as if (numbers!=null) to avoid this exception. Hello and thank for your product and help: Xamarin Form: 5.0.0.2125 Syncfution: 19.3.0.45 Platform: Android 1==> I have sfpopup1 defined in mypage.xaml 2==> this sfpopup1 call a custom view its datatemplate : <sfpopup:PopupView.ContentTemplate> <DataTemplate> <ContentView> <ContentView.Content> <customViews:mycustomView/> </ContentView.Content> </ContentView> </DataTemplate> </sfpopup:PopupView.ContentTemplate> 3==> in mycustomView i have a definition of sfpopup2. PB scenario : when i click for the first time on sfpopup1 it show me the data and i can click to show the second popup2 with success. But when i close the popup2 and then i close the popup1, then i click to open the popup1 again, for the second time, i got this error : $exception {System.NullReferenceException: Object reference not set to an instance of an object. at Syncfusion.XForms.Android.PopupLayout.PopupLayoutDependencyService.Show (System.Object nativeObject, Syncfusion.XForms.PopupLayout.SfPopupLayout formsPopup) [0x00017] in <2a371ae052bd4549be9649e4f0ade4d0>:0 at Syncfusion.XForms.PopupLayout.SfPopupLayout.Show (System.Boolean isFullScreen) [0x00018] in <452eb09ad7204bdc8957931a3d022370>:0 at Syncfusion.XForms.PopupLayout.SfPopupLayout.OnIsOpenChanged (Xamarin.Forms.BindableObject bindable, System.Object oldValue, System.Object newValue) [0x0007f] in <452eb09ad7204bdc8957931a3d022370>:0 at Xamarin.Forms.BindableObject.SetValueActual (Xamarin.Forms.BindableProperty property, Xamarin.Forms.BindableObject+BindablePropertyContext context, System.Object value, System.Boolean currentlyApplying, Xamarin.Forms.Internals.SetValueFlags attributes, System.Boolean silent) [0x00120] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:512 at Xamarin.Forms.BindableObject.SetValueCore (Xamarin.Forms.BindableProperty property, System.Object value, Xamarin.Forms.Internals.SetValueFlags attributes, Xamarin.Forms.BindableObject+SetValuePrivateFlags privateAttributes) [0x00173] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:446 at Xamarin.Forms.BindingExpression.ApplyCore (System.Object sourceObject, Xamarin.Forms.BindableObject target, Xamarin.Forms.BindableProperty property, System.Boolean fromTarget) [0x00226] in D:\a\1\s\Xamarin.Forms.Core\BindingExpression.cs:160 at Xamarin.Forms.BindingExpression.Apply (System.Boolean fromTarget) [0x0003e] in D:\a\1\s\Xamarin.Forms.Core\BindingExpression.cs:56 at Xamarin.Forms.BindingExpression+BindingExpressionPart.<PropertyChanged>b__49_0 () [0x00000] in D:\a\1\s\Xamarin.Forms.Core\BindingExpression.cs:762 at Xamarin.Forms.BindingExpression+BindingExpressionPart.PropertyChanged (System.Object sender, System.ComponentModel.PropertyChangedEventArgs args) [0x000cb] in D:\a\1\s\Xamarin.Forms.Core\BindingExpression.cs:773 at Xamarin.Forms.BindingExpression+WeakPropertyChangedProxy.OnPropertyChanged (System.Object sender, System.ComponentModel.PropertyChangedEventArgs e) [0x00012] in D:\a\1\s\Xamarin.Forms.Core\BindingExpression.cs:666 NB : if i change the call of popup2 by navigation to a new page from the popup1, it works fine. How do I fix NullReferenceException object reference not set to an instance of an object?The best way to avoid the "NullReferenceException: Object reference not set to an instance of an object” error is to check the values of all variables while coding. You can also use a simple if-else statement to check for null values, such as if (numbers!= null) to avoid this exception.
How do I fix NullReferenceException in C#?You can eliminate the exception by declaring the number of elements in the array before initializing it, as the following example does. For more information on declaring and initializing arrays, see Arrays and Arrays. You get a null return value from a method, and then call a method on the returned type.
What causes object reference not set to an instance of an object?The message "object reference not set to an instance of an object" means that you are referring to an object the does not exist or was deleted or cleaned up. It's usually better to avoid a NullReferenceException than to handle it after it occurs.
What is System NullReferenceException in C#?C#NullReferenceException
NullReferenceException is thrown in C# when you try to access a property of method on an object of null reference. Hence the name Null Reference. Simply put, the object is null. The object here could be a string, a class object, or anything.
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System NullReferenceException object reference not set to an instance of an object Xamarin
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