Question 79430 in Flutter Question posted in
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Flutter, dart: what's the difference between these snippets of code?

Code snippet A is working, but not snippet B. I check variable "image"s data type with print(), both A and B’s image (variable) has a datatype (XFile), not a Null. But B is still not working….

final XFile? image = await _picker.pickImage(source: ImageSource.gallery);

print(image);

// Code snippet A
if (image == null) return null;
return File(image.path);

// Code snippet B
return File(image!.path);
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2

Answers


  1. 0

    image can be null, In Code A you check for nullable value so you won’t get exception, but in code B you are using ! on nullable value which is wrong.

    If you look for short form you can try this:

    return image == null ? null : File(image.path);
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  2. 0

    The meaning of your code snippet A is:

    If the image variable is null it will return null otherwise it will return the image variable.

    The meaning of your code snippet B is:

    It returns the image variable, although the image variable may be null.

    If you use code snippet B, you use ! and change the variable from a nullable type to a non-nullable type, and the variable is actually empty (has no value) and you can’t use .path so it returns an error.

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