Class

# TypeMismatchException

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## Description

Occurs when you try to assign a value to an object that is an incorrect data type.

## Properties

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| Name                                             | Type                               | Read-Only | Shared |
|--------------------------------------------------|------------------------------------|-----------|--------|
| `ErrorNumber<typemismatchexception.errornumber>` | `Integer</api/data_types/integer>` |           |        |
| `Message<typemismatchexception.message>`         | `String</api/data_types/string>`   |           |        |

## Methods

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| Name                                              | Parameters                                                                                              | Returns                                    | Shared |
|---------------------------------------------------|---------------------------------------------------------------------------------------------------------|--------------------------------------------|--------|
| `Constructor<typemismatchexception.constructor0>` | message As `String</api/data_types/string>` = "", errorNumber As `Integer</api/data_types/integer>` = 0 |                                            |        |
| `Stack<typemismatchexception.stack>`              |                                                                                                         | `String()</api/data_types/string>`         |        |
| `StackFrames<typemismatchexception.stackframes>`  |                                                                                                         | `StackFrame()</api/exceptions/stackframe>` |        |

## Property descriptions

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TypeMismatchException.ErrorNumber

**ErrorNumber** As `Integer</api/data_types/integer>`

> Used to contain an error number that describes the runtime error.

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TypeMismatchException.Message

**Message** As `String</api/data_types/string>`

> Used to contain descriptive text to display when the runtime exception is encountered.

## Method descriptions

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TypeMismatchException.Constructor

**Constructor**(message As `String</api/data_types/string>` = "", errorNumber As `Integer</api/data_types/integer>` = 0)

> <div class="note">
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> Note
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> `Constructors</api/language/constructor>` are special methods called when you create an object with the `New</api/language/new>` keyword and pass in the parameters above.
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> Used to raise your own `RuntimeException</api/exceptions/runtimeexception>` with a *message* and optional error number.

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TypeMismatchException.Stack

**Stack** As `String()</api/data_types/string>`

> Returns a `String</api/data_types/string>` array that contains a list of all of the methods in the stack from the main entrypoint to the point at which the exception was invoked.
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> The stack contains all the method names up and including the current method name.
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> This feature only works if the **IncludeFunctionNames** property on the App object is selected in the Shared Build Settings.
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> In addition to your own method calls, you will also see framework method calls, but these may not always be completely accurate due to insufficient symbols for the OS to resolve.

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TypeMismatchException.StackFrames

**StackFrames** As `StackFrame()</api/exceptions/stackframe>`

> Returns an array containing the stack when the exception was first raised.

## Notes

A <span class="title-ref">TypeMismatchException</span> error occurs when you try to assign a value of an incorrect data type to an object. This error can occur only if the compiler cannot determine the type of the value at compile time - for example, when using `variants</api/data_types/variant>`. Ordinarily, the compiler catches incorrect typing when you try to compile the application.

## Sample code

The following code assigns a picture that has been added to the Project Editor to the `variant</api/data_types/variant>`, v, and then tries to assign v to an `Integer</api/data_types/integer>`. The `Exception</api/exceptions/exception>` statement displays a message box, allowing the developer to track down the problem. Exception handling prevents the built application from quitting when the error occurs.

``` xojo
Var v As Variant
Var i As Integer
v = ProductLogo ' a picture
i = v
Exception err
  If err IsA TypeMismatchException Then
    MessageBox("The variable i must be assigned a number!")
  End If
```

## Compatibility

|                       |     |
|-----------------------|-----|
| **Project Types**     | All |
| **Operating Systems** | All |

<div class="seealso">

`RuntimeException</api/exceptions/runtimeexception>` parent class; `Function</api/language/function>`, `Raise</api/language/raise>`, `Sub</api/language/sub>` statements; `Nil</api/language/nil>` datatype; `Exception</api/exceptions/exception>`, `Try</api/language/try>` statements.

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