How can I initialize a default value of QComboBox without to click it?

Question

How can I initialize a default value of QComboBox without to click it? I tried with

ui->combBox->setCurrentIndex(1);

but when I read the value at first I get unfortunately a -1 and only after the QComboBox was clicked its value become 1.

Solution 1

I solved the problem. The ui->combBox->setCurrentIndex(1); was in constructor before connect(ui->combBox,SIGNAL(currentIndexChanged(int)).... @Nikos C. thank you very much for a good tip.

Solution 2

Are you sure there's at least two values in the QComboBox? Counting begins from 0, not 1. If you want to select the first value, you need to:

ui->combBox->setCurrentIndex(0);

If that's not the problem, and you indeed have two values in the combo box, then make sure that the ui has been set up first. This call needs to execute first:

ui->setupUi(this);

It's what actually fills the combo box with the values specified in the .ui file.

Comments

[tmpearce]

Does the combobox have at least 2 items when you try to set the index to 1?

[Viktor Tarasov]

Yes, I'm sure. The values: true(1) and false(0) were defined in MainWindow.ui file. And then in constructor I try to set value ui->combBox->setCurrentIndex(1);

[Viktor Tarasov]

I can set the value in the MainWindow to true(1) or false(0) it works correct, but if read the value of the QComboBox before to click it, I get a -1 :((

[Nikos C.]

Are you trying to select index 1 before the ui has been setup, perhaps? That is, before the ui->setupUi(this); call in the constructor?

[Viktor Tarasov]

But I've just looked it. It's not the problem: at first I call ui->setupUi(this); and then ui->combBox->setCurrentIndex(0); :(( It's so fare correct.

[Nikos C.]

Make sure you don't call ui->setupUi(this) again later. Qt writes that call automatically when you create the .ui and .cpp files. You could also post the code of the constructor in your question, so that we can verify this.

[Viktor Tarasov]

@Nikos Chantziaras "Make sure you don't call ui->setupUi(this) again later." I'm sure. That's not problem.. also my question stay up to date :((

[Nikos C.]

Still, you might want to post the constructor in your question. Maybe then someone can spot what's wrong.