开关 - flutter 中的外壳

Question

I dont know why i cant send data of "altMenuIndex" to "degisenMenu()". When i change inside of switch manually, it works. But when i change like "int altMenuIndex = 2", it doesnt work.

The codes below show the "default" value.

class AltMenuDegistir {
  int altMenuIndex = 1;
  AltMenuDegistir({this.altMenuIndex});

  degisenMenu() {
    switch (altMenuIndex) {
      case 1:
        return Kutuphane();
        break;
      case 2:
        return KitapAra();
        break;
      case 3:
        return TalebeEkle();
        break;
      case 4:
        return TalebeAra();
        break;
      default:
        return Container(
          child: Center(
            child: Text("Bir şeyler ters gitti!"),
          ),
        );
    }
  }
}

Answer 1

Probably you are missing the pass altMenuIndex in constructor

  var x = AltMenuDegistir(altMenuIndex:2);
  x.degisenMenu();

  var y = AltMenuDegistir(altMenuIndex:3);
  y.degisenMenu();

So, why not change the degisenMenu method?

degisenMenu(altMenuIndex) { // <====== altMenuIndex 
 switch (altMenuIndex) {
      case 1:
        return Kutuphane();
        break;
      case 2:
        return KitapAra();
        break;
      case 3:
        return TalebeEkle();
        break;
      case 4:
        return TalebeAra();
        break;
      default:
        return Container(
          child: Center(
            child: Text("Bir şeyler ters gitti!"),
          ),
        );
    }
  }

Then call this method through each button with passing appropriate index.

For instance, Kutuphane, call it like degisenMenu(1) etc.

Answer 2

The default value should be set inside the constructor:

int altMenuIndex;
AltMenuDegistir({this.altMenuIndex = 1});

When you call the constructor yo can set the value:

AltMenuDegistir(altMenuIndex: 2)