On March 3, 2021, Google developers introduced Flutter 2. What has appeared in the new version of the Dart language? What about the development and support of applications created using previous Flutter versions now? And most importantly, how difficult would it be to migrate to version 2? In this article, we will describe in detail the experience of migrating an application to a new version of Flutter and the problems that may arise during the migration process.
Who is Flutter and why is Flutter needed?
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ComboMeal(Drink? drink) {
drink!.addIce(); //
}
ComboMeal(null);
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ComboMeal(Drink drink) {
if (drink.bestTemperature != null) {
keepTemperature(drink.bestTemperature); //
}
}
ComboMeal(Drink drink) {
int? bestTemperature = drink.bestTemperature;
if (bestTemperature!= null) {
keepTemperature(bestTemperature); // null safety
}
}
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ComboMeal(Drink? drink) {
drink?.addIce(); // addIce
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ComboMeal(null);
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keepTemperature(drink.bestTemperature ?? 70);
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class ComboMeal {
String burgerName; //
void comboWithCheeseburger() {
burgerName = 'heeseburger';
}
void comboWithChickenBurger() {
burgerName = 'Chicken burger';
}
getComboMealName() {
return 'ComboMeal with ' + burgerName;
}
}
, «burgerName» null .
class ComboMeal {
String? burgerName;
void comboWithCheeseburger() {
burgerName = 'heeseburger';
}
void comboWithChickenBurger() {
burgerName = 'Chicken burger';
}
getComboMealName() {
return 'Combo meal with ' + burgerName!;
}
}
late nullable.
class ComboMeal {
late String burgerName; //null safety
void comboWithCheeseburger() {
burgerName = 'heeseburger';
}
void comboWithChickenBurger() {
burgerName = 'Chicken burger';
}
getComboMealName() {
return 'Combo Meal with ' + burgerName;
}
}
ComboMeal comboMeal = ComboMeal();
comboMeal.comboWithCheeseburger();
print(comboMeal.getComboMealName());
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late String burgerName = _getSurpriseName();
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