how to add item in a list widget on clicking of a pushbutton

[jpn]

You can't do these from within Designer. Use either multiple or single inheritance approach and create custom slots for doing those tasks.

connect(ui.pushButton, SIGNAL(clicked()), this, SLOT(newItem()));
 
void MyForm::newItem()
{
    ui.listWidget->addItem(ui.lineEdit->text());
}

connect(ui.pushButton, SIGNAL(clicked()), this, SLOT(newItem()));

void MyForm::newItem()
{
    ui.listWidget->addItem(ui.lineEdit->text());
}

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