I am trying to create an android app(it is not better on pc) with qt, and when I run it, I am getting this error in run console: F : QWidget: Must construct a QApplication before a QWidget Apparently the problem is, that I use QDesktopWidget in My Calculations class. Calculations.h: #ifndef CALCULATIONS_H #define CALCULATIONS_H #include <QApplication> #include <QPushButton> #include <QProgressBar> #include <QDesktopWidget> class Calculations { public: Calculations(); static int Percent(int source, int percent); void row(QPushButton *p, QProgressBar *b); private: int c = 28; static QDesktopWidget dw; }; #endif // CALCULATIONS_H Calculations.cpp: #include "calculations.h" Calculations::Calculations() { } int Calculations::Percent(int source, int percent){ return source*percent/100; } void Calculations::row(QPushButton *p, QProgressBar *b){ static QDesktopWidget dw; p->setGeometry(Percent(dw.width(),75),Percent(dw.height(),c),Percent(dw.width(),25),Percent(dw.height(),4)); b->setGeometry(0,Percent(dw.height(),c),Percent(dw.width(),75),Percent(dw.height(),4)); c+=4; return; } MainWindow.cpp: #include "mainwindow.h" #include "ui_mainwindow.h" MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent) , ui(new Ui::MainWindow) { ui->setupUi(this); QDesktopWidget dw; dw.width(); // ui->Clickme->setGeometry(Calculations::Percent(dw.width(),15),dw.height()/8,Calculations::Percent(dw.width(),70),dw.height()/8); Calculations c; ui->Clickme->setGeometry(c.Percent(dw.width(),15),dw.height()/8,c.Percent(dw.width(),70),dw.height()/8); c.row(ui->pushButton,ui->progressBar); c.Percent(100,12); } MainWindow::~MainWindow() { delete ui; } Calculations.h is included in MainWindow.h Can someone help me?

@rktech said in F : QWidget: Must construct a QApplication before a QWidget : static QDesktopWidget dw; This is absolutely not needed at all. Neither static nor as value nor as member.

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F : QWidget: Must construct a QApplication before a QWidget

Solved General and Desktop

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R rktech

Cleaned, remaked and now it worked
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mrjj
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wrote on last edited by

#21

@rktech
Super. So it was the statics.
So i also learned something new :)
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