CODEWITHSUNDEEP
flutterdartvisual-studio-code
Dicska
Dicska

Reputation: 1

Dart crashes when calling toString() of the parent class

I probably just simply overlooked something, but I have a simple class tree where the superclass has a simple toString() method. When calling it from the derived class instance, I get a crash in VS Code:

class Item {
  String status = "";
  String name = "";
  Item();

  String toString() {
    return "$this.name ($this.status)";
  }
}

class MiscItem extends Item {}

class FoodItem extends Item {}

class DrinkItem extends Item {}

DrinkItem coke1 = new DrinkItem();
print(coke1.toString());

Then it drops dead with:

===== CRASH =====
ExceptionCode=-1073741819, ExceptionFlags=0, ExceptionAddress=00007FF7E9F498FE
version=2.16.1 (stable) (Tue Feb 8 12:02:33 2022 +0100) on "windows_x64"
pid=14904, thread=14540, isolate_group=main(000001FED427C020), isolate=main(000001FED4295B80)
isolate_instructions=7ff7e9e15450, vm_instructions=7ff7e9e15460
Stack dump aborted because GetAndValidateThreadStackBounds failed.
Exited (3221226505)

What did I mess up here? AFAIK DrinkItem should inherit both the superclass' toString() method and the status and name properties. Still, calling DrinkItem's toString() crashes.

Upvotes: 0

Views: 170

Answers (1)

Thierry
Thierry

Reputation: 8383

You need curly braces in your string interpolation:

String toString() {
  return "${this.name} (${this.status});
}

Otherwise, it will be equivalent to "${this}.name (${this}.status)" and hence recursively invoke your toString() method.

By the way, in Dart, you don't have to use this inside the class. You can simplify your toString() method to:

String toString() {
  return "$name ($status);
}

Upvotes: 1

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