CODEWITHSUNDEEP
dartflutter
Michal Takáč
Michal Takáč

Reputation: 1055

Dart compare two strings return false

Im new to dart and have a problem during building my Flutter application.

I have a firestore database as a backend and im getting data from there.

When i want to compare part of the data called status with the text 'CREATED', using == comparator, dart will return false.

Can someone explain why and how to check it properly?

rideObject is a Map

enter image description here

Update:

Here is the function that has the condition in it:

Widget _getPage() {
 if (rideObject == null) {
      return OrderRidePage(
          address: address,
          ridesReference: reference,
          setRideReference: this._setRideReference);
    } else {
      print(rideObject['status']);
      if (rideObject['status'] == "CREATED") {
        return LoadingPage(
            removeRideReference: this._removeRideReference,
            rideReference: rideReference);
      } else {
        return RidePage(
            address: address,
            ridesReference: reference,
            setRideReference: _setRideReference);
      }
    }
  }

The print statement returns to output:

I/flutter (15469): CREATED

Here you can see the structure of the rideObject

enter image description here

Funnily enough, the rideObject["status"] is String type as shown in here in console:

rideObject["status"] is String
true
"CREATED" is String
true
rideObject["status"]
"CREATED"
rideObject["status"] == "CREATED"
false

Upvotes: 8

Views: 13209

Answers (5)

hardanger
hardanger

Reputation: 2627

Building off @yonez's answer, the encoding may be different after a string has been passed through a server.

Instead of: String.fromCharCodes(data)

Try using: utf8.decode(data)

Upvotes: 0

Celt K. B.
Celt K. B.

Reputation: 789

If both are really strings, you can use "compareTo" which will return 0 if both are equal.

if(str1.compareTo(str2)==0){
}

It is explained here: https://www.tutorialspoint.com/dart_programming/dart_programming_string_compareto_method.htm

Upvotes: 5

KevinZR
KevinZR

Reputation: 11

The answer for this problem is in the documentation of flutter: https://api.flutter.dev/flutter/dart-core/String/compareTo.html

you can do:

(var.compareTo('WORD') == 0)

are equivalent

.compareTo()

Returns a negative value if is ordered before, a positive value if is ordered after, or zero if and are equivalent.thisother

Upvotes: 1

yonez
yonez

Reputation: 178

The String you got from your server is probably encoded and contains special character which you can't see, try to compare the hex values of both of the strings, and then replace all the special characters from the String returned by the server.

Using this, you can see the actual non visible difference between the two strings:

var text1 = utf8.encode(hardcodedText).toString();
var text2 = utf8.encode(textFromServer).toString();

Upvotes: 5

Michal Takáč
Michal Takáč

Reputation: 1055

I don't have a particular solution to this, but I updated to latest Flutter version that came up today, moved the "CREATED" string into constant and resolved an unrelated warning for another part of the application, and it suddenly started to work.

Upvotes: 3

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