dart alternate for a lot of if elseiif

Question

I want to replace an URL String in Dart with another String. Example:

if (url == "http://www.example.com/1") {
home = "example";
} else if (url == "http://www.example.com/2") {
home = "another example";
}

Isn't there a better way with less code and maybe faster? I'd have to do this over 60 times..

A "better way" is highly opinion based. Better in what ? Readbility ? Maintainability ? Speed ? — Muldec, Jul 29 '19 at 07:57
Well, your second case could be removed entirely since its condition will never be true... — jamesdlin, Jul 29 '19 at 08:32
It's just a typo.. Of course there would be another number at the end. — Jona, Jul 29 '19 at 08:51

score 7 · Accepted Answer · answered Jul 29 '19 at 07:59

7

If you want less code, you can do somtehing like this :

homes = {
  "http://www.example.com/1": "example",
  "http://www.example.com/2": "another example",
  "http://www.example.com/3": "yet another one",
};
home = homes[url];

answered Jul 29 '19 at 07:59

Muldec

4,641
1
25
44

score 5 · Answer 2 · answered Aug 07 '19 at 08:58

I like Muldec's answer as I personally find switch statements to be a bit awkward to read. I also like the option of having a default so you could 'kind of' redefine the switch statement. The additional benefit is that you can use it inline as an expression and it is still typesafe...like this.

case2(myInputValue,
  {
    "http://www.example.com/1": "example",
    "http://www.example.com/2": "another example",
    "http://www.example.com/3": "yet another one",
  }, "www.google");

The case2 code could be

TValue case2<TOptionType, TValue>(
  TOptionType selectedOption,
  Map<TOptionType, TValue> branches, [
  TValue defaultValue = null,
]) {
  if (!branches.containsKey(selectedOption)) {
    return defaultValue;
  }

  return branches[selectedOption];
}

score 1 · Answer 3 · answered Jul 29 '19 at 07:59

You can use a switch statement.

switch(variable_expression) { 
   case constant_expr1: { 
      // statements; 
   } 
   break; 

   case constant_expr2: { 
      //statements; 
   } 
   break; 

   default: { 
      //statements;  
   }
   break; 
}

References

score 0 · Answer 4 · answered Apr 20 '23 at 17:20

Mapp

              var mapper = {
                  'discountCode1': 0.5,
                  'discountCode2': 0.7,
                  'discountCode3': 0.8,
                };

Function

             double getDiscount(double price, String discountCode) {
                  if (mapper.containsKey(discountCode)) {
                    return mapper[discountCode]! * price;
                  } else {
                    return price;
                  }
                }

score -2 · Answer 5 · answered Jul 29 '19 at 08:07

-2

Just store the value "http://www.example.com" in a string variable and concatinate everytime. Refer below code

String originalUrl = 'https://www.example.com';
if (url == originalUrl + '/1') {

}

answered Jul 29 '19 at 08:07

Ritesh Sharma

77
3

Or else you can use Switch Case – Ritesh Sharma Jul 29 '19 at 08:07

dart alternate for a lot of if elseiif

5 Answers5

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