Changing Color of a List Item when tap

Does anybody knows why this piece of code its not working corretly? The color it's not changing when I tap.

It might be a simple question, but I'm not an expert, I'm still learning.


var CardColor = Colors.blue;

  void changeColor() {
    CardColor = Colors.primaries[Random().nextInt(Colors.primaries.length)];
  }

  Widget BuildMainListView() {
    return ListView(children: [
      for (int index = 0; index < 25; index  )
        Card(
            color: CardColor,
            child: ListTile(
              title: Text(
                'Item Número $index',
                textScaleFactor: 1.2,
              ),
              subtitle: Text('Este é o item de númer $index'),
              trailing: Icon(Icons.star),
              onTap: () => changeColor,
            ))
    ]);
  }

The function does not work, I tried without a functiont too, same result.

CodePudding user response：

First, make sure you're using StatefulWidget, Then you will need to update the state with setState when changing cardColor:

void changeColor() {
  CardColor = Colors.primaries[Random().nextInt(Colors.primaries.length)];
  setState(() {});    // add this
 }

finally, assign the method directly to onTap, like this:

     Widget BuildMainListView() {
    return ListView(children: [
      for (int index = 0; index < 25; index  )
        Card(
            color: CardColor,
            child: ListTile(
              title: Text(
                'Item Número $index',
                textScaleFactor: 1.2,
              ),
              subtitle: Text('Este é o item de númer $index'),
              trailing: Icon(Icons.star),
              onTap: changeColor, // remove () =>
            ))
    ]);
  }