Difference between Display and Shell

A typical SWT sample code looks li开发者_StackOverflowke the following code:

final Display display = Display.getDefault();
final Shell shell = createMyShell(display);
shell.open();
while (!shell.isDisposed()) {
    if (!display.readAndDispatch()) {
        display.sleep();
    }
}

What is the difference between Display and Shell?

If multiple windows have to be shown, does each one need an own loop?

---

You can have multiple shells with a single Display and a single while loop handing event dispatch. Create the display, create the Shell(s) from the Display, and then start the single UI event dispatcher loop. See http://www.chrisnewland.com/av/111/swt-best-practice-single-display-multiple-shells

---

Yes, if you have to show multiple windows (shells), you must have a loop for each one.

But there is only one Display object in an application that you need to create.

---

ChrisWhoCodes is quite correct. The following code implements his model.

import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

public class MultipleShells {
  public MultipleShells(Display display) {
    Shell[]             shells;
    MainWindows         mainWindow;
    mainWindow = new MainWindows(display, "Shell 1");    
    mainWindow = new MainWindows(display, "Shell 2");

    while (!display.isDisposed()) {
      if (!display.readAndDispatch()) {
        shells = display.getShells();
        if (shells.length == 0)
          break;
        display.sleep();
      }
    }
  }

  public static void main(String[] args) {
    Display display = new Display();
    MultipleShells mainApp = new MultipleShells(display);
    display.dispose();
  }
}  

class MainWindows {
    protected MainWindows(Display parent, String title) {  
    Shell               mainShell;
    mainShell = new Shell(parent);
    mainShell.setText(title);
    mainShell.open();
  }  
}