How to change values in OnTap Function when used in a for loop in Flutter

Question

This is how my code looks like:

        List<Widgets> abc = [];

        for(int a = 0;a<5;a++)
        {
        abc.add(FlatButton(onTap:(){ print(a);},
                           child:Text("Hello - ${a}")
                           )
                 );
        }

When user clicks on "Hello - 2" Button, I want the output on console to be 2 but the output displayed is 5.

I have simplified the original problem in the form of this small programming question.I have checked a lot on internet but was unable to get any answer. Help me out please!!

Solution

Your code is working just fine.

List<Widget> abc = [];

  @override
  Widget build(BuildContext context) {
    for (int a = 0; a < 5; a++) {
      abc.add(FlatButton(
          onPressed: () {
            print(a);
          },
          child: Text("Hello - $a")));
    }
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: ListView.builder(
          itemCount: abc.length,
          itemBuilder: (context, index) {
            return abc[index];
          },
        ),
      ),
    );

And how can it return 5 when the max value of a is 4?

Comments

[Cread Dotson]

It looks like you're not storing the a variable for each button. You're just converting it to a string to make the button name but when the button is pushed "a" still refers to your incrementing variable.

[Admin]

Yeah thats exactly what was happening the last time I checked

[Admin]

I don't know why and how this is working fine but last when I checked it was not storing the value of a. It was just taking the last value of a which was somehow 5. At that time the system may be taking garbage value (idk, it could be).

[Admin]

In the original problem, I was displaying the result in the form of a List and clicking on those result tiles, I wanted to animate to new Screen using Hero widget. So I made a function with a for loop and was using loop variable values as a tag for hero widget but every time the tag was taking the value '5' if the above-mentioned loop was used. I had no idea why this was happening.

[Abhishek]

So is this solution working for you ? or something else has to be addressed here? Update your question if you are having problems or accept the answer if this answer correctly addresses and solves your problem.