对于和如果在 flutter

Question

I have this code

String passou = 'true';
for (int j = 0; j < items.length; j++) {
      verifyAllProd(items[j].ref).then(
      (quanti) {
        if (double.parse(quanti) <= 0) {
           passou = 'false';
           showDialog(
            context: context,
            builder: (context) {
              return AlertDialog(
                title: const Text("Mensagem"),
                content: Text("O produto ${items[j].name} já nao está disponivel"),
               );
             },
           );
         }
        if (double.parse(quanti) < items[j].quantity &&
            double.parse(quanti) != 0) {
             passou = 'false';                
             showDialog(
             context: context,
             builder: (context) {
                  return AlertDialog(
                     title: const Text("Mensagem"),
                     content: Text("O produto ${items[j].name} apena tem disponivel: $quanti"),
            );
          },
        );
      }
    },
  );
}
print(passou);
if (passou == 'true') {
     Navigator.push(
     context,
     MaterialPageRoute(
     builder: (context) => const ListPaymentTrans(),
    ),
  );
}

I don't know why but when I use this code in my app the "if" is called first than "for". That is, I click on the button and instead of the "if" wait for the "for" to be asked to see if the "passou" will receive the value false. It does the "if" right away and doesn't wait for the "for" to finish (opens the page).

I don't know if there is any way to change this?

Answer 1

You are doing it the wrong way. Try this instead of using boolean as string use it as boolean.

    bool passou = false;
for (int j = 0; j < items.length; j++) {
      verifyAllProd(items[j].ref).then(
      (quanti) {
        if (double.parse(quanti) <= 0) {
           passou = false;
           showDialog(
            context: context,
            builder: (context) {
              return AlertDialog(
                title: const Text("Mensagem"),
                content: Text("O produto ${items[j].name} já nao está disponivel"),
               );
             },
           );
         }
        if (double.parse(quanti) < items[j].quantity &&
            double.parse(quanti) != 0) {
             passou = false;                
             showDialog(
             context: context,
             builder: (context) {
                  return AlertDialog(
                     title: const Text("Mensagem"),
                     content: Text("O produto ${items[j].name} apena tem disponivel: $quanti"),
            );
          },
        );
      }
    },
  );
}
print(passou);
if (passou) {
     Navigator.push(
     context,
     MaterialPageRoute(
     builder: (context) => const ListPaymentTrans(),
    ),
  );
}