write on ui label from different class in qt - c++

Question

I am using Qt in my project and facing some difficulty in accessing ui label from other class,I have mainwindow and Yar class as shown below.
mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include "yar.h"
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
Yar b;
private:
Ui::MainWindow *ui;
public slots:
void dispal();
private slots:
void on_pushButton_clicked();
};
#endif // MAINWINDOW_H
mainwindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
QObject::connect(ui->pushButton,SIGNAL(clicked()),&b,SLOT(lll()));
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::dispal(){
ui->label->setText("hello");
}
Yar.h
#ifndef YAR_H
#define YAR_H
#include <QObject>
class Yar : public QObject
{
Q_OBJECT
public:
explicit Yar(QObject *parent = 0);
public slots:
void lll();
};
#endif // YAR_H
void MainWindow::on_pushButton_clicked()
{//ui->label->setText("hello");
//b.wrrrot();
//dispal();
}
Yar.cpp
#include "yar.h"
#include <iostream>
Yar::Yar(QObject *parent) :
QObject(parent)
{
//setupUi(this);
//QObject::connect(&a, SIGNAL(dis), &a, SLOT(dispal()));
//emit wrrrot();
}
void Yar::lll(){
//emit wrrrot();
std::cout<<"gfggdf"<<std::endl;
}
In my gui i have one push button and one label, I have connected push button with lll() function of class Yar and when I click push button it is displaying gfggdf in console but I want to display this text in ui label, could you please help me how can I display my data in ui label from function lll();

Answer 1

One possible solution is to emit signal from Yar::lll() i.e.
emit updateLabelText("your text");
And connect this signal to the slot that handles GUI (changes label with given text) in the MainWindow.