QFile not readable

[seux]

Hello out there,
i am trying to read from a file that the user chooses via a QFileDialog, but after that the file is not readyble...

file = new QFile(QFileDialog::getOpenFileName(....));
if(file.isReadable() != true)
{
     //This gets executed
     QMessageBox msg(QMessageBox::Information, "DEBUG", "File not readable", QMessageBox::Ok);
     msg.show();
     return;
}

file = new QFile(QFileDialog::getOpenFileName(....));
if(file.isReadable() != true)
{
     //This gets executed
     QMessageBox msg(QMessageBox::Information, "DEBUG", "File not readable", QMessageBox::Ok);
     msg.show();
     return;
}

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The interesting thing is, that the messagebox never really appears. But when I start the programm in the debugger i can see step by step that the code in the if condition gets executed and that the messgebox is not complete drawn (Just a empty MsgBox appears without text, just the "DEBUG" title).

What is going wrong?

[NullPointer]

Try:

QString filename=QFileDialog::getOpenFileName(....);
if(filename.isEmpty()) return;
file = new QFile(filename);
file->open(QIODevice::ReadOnly); // Use ReadWrite if you want to write on it...
if(file.isReadable() != true)
{
     //This gets executed
     QMessageBox msg(QMessageBox::Information, "DEBUG", "File not readable", QMessageBox::Ok);
     msg.show();
     return;
}

QString filename=QFileDialog::getOpenFileName(....);
if(filename.isEmpty()) return;
file = new QFile(filename);
file->open(QIODevice::ReadOnly); // Use ReadWrite if you want to write on it...
if(file.isReadable() != true)
{
     //This gets executed
     QMessageBox msg(QMessageBox::Information, "DEBUG", "File not readable", QMessageBox::Ok);
     msg.show();
     return;
}

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Here: QFile and QIODevice
Hth.

[stampede]

Of course you cannot see the message box:

{
QMessageBox msg(QMessageBox::Information, "DEBUG", "File not readable", QMessageBox::Ok);
msg.show();
return; // message box is destroyed here
}

{
QMessageBox msg(QMessageBox::Information, "DEBUG", "File not readable", QMessageBox::Ok);
msg.show();
return; // message box is destroyed here
}

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Message box is deleted immediately after creation, use "exec()" instead of "show()". Or try with static methods:

{
QMessageBox::information(this,"DEBUG", "File not readable"); // blocks until message box is closed
return;
}

{
QMessageBox::information(this,"DEBUG", "File not readable"); // blocks until message box is closed
return;
}

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