Thread: Flyweight Design Pattern

Why do you think you need to do this?

The flyweight design has nothing to do with equality. Your test would also fail with Strings.

You could create a thousand instances of a large image and compare the memory consumption to that of creating a single instance. But again, why do you think you need to do this?

You're comparing apples and oranges. You're using the new keyword with the images, but not with the Strings. Try this:

 public class Main{
	 public static void main(String... args){
 
		 String test1 = new String("test");
		 String test2 = new String("test");
 
		 System.out.println(test1 == test2);
	 } 
}

Or even more similar to your image example:

 
 public class Main{
	 public static void main(String... args){
 
		 StringWrapper test1 = new StringWrapper("test");
		 StringWrapper test2 = new StringWrapper("test");
 
		 System.out.println(test1 == test2);
	 } 
}
 
 class StringWrapper{
 
	 String s;
 
	 public StringWrapper(String s){
		 this.s = s;
	 }
 }

The point is, using equality to test for the flyweight design is not really valid.

Further, there is no concrete Image class, so some subtypes of Image could use the flyweight design and others could not. It might even be platform dependent!

1) Take a look at the API for the intern method of the String Class
2) Take a look at the API for the ImageIO class, pay special attention to the methods with the name 'cache' in them