Is there focus event for line edit?

[navi1084]

ui->edtFileName->installEventFilter(ui->edtFileName);
keyBoard= new KeyboardEntryImpl(ui->edtFileName,NULL);
}

But in the bool exportData::eventFilter(QObject *obj, QEvent *ev)
{
}

You made a mistake here. You have install the event filter of edtFileName to edtFileName. If you want to use event filter in "exportData" class
then you should use function in this way

exportData->installEventFilter(ui->editFileName)

exportData->installEventFilter(ui->editFileName)

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Now your code
bool exportData::eventFilter(QObject *obj, QEvent *ev)
{
}

should work fine