Question

With performance in consideration, how would you store multiple overlay types for the entire of your GWT app to use upon request?

Answer 1

If I understand correctly, you are wanting to reference an overlay type from anywhere within your application. In that case, consider creating a public static variable.

For example, say we have a JavaScript Overlay Type called Book. Inside of it, we can create a static variable to hold our global instance.

public class Book extends JavaScriptObject {
   public static Book instance; // The global

   protected Book(){}

   public final native String getName()/*-{ 
      return this.name; 
   }-*/;

   public final native void setName(String name)/*-{
      this.name = name; 
   }-*/;
}

Then later on, we reference it from wherever we want:

Book.instance = (Book) JavaScriptObject.createObject();
Book.instance.setName("How I Sailed the Seven Seas");
GWT.log( Book.instance.getName() );

Truth be told, this is how any “global” variable works in Java. Overlay types happen to work the same way!

Do note that there is no magic happening by putting the instance inside of the Book class. You could very easily do the same thing:

public class FooBar{
   public static Book global_book;
}

and later:

FooBar.global_book.setName("My Biography")