CODEWITHSUNDEEP
java
louie mcconnell
louie mcconnell

Reputation: 761

Can someone please explain this Java line simply?

Graphics2D g2 = (Graphics2D) g;

Honestly, the entire g2 and g concept is confusing. Can anyone explain it? Thanks.

Additionally, an explanation of the difference between g and g2 would be nice.

Upvotes: 0

Views: 70

Answers (2)

Pier-Alexandre Bouchard
Pier-Alexandre Bouchard

Reputation: 5235

You cast a Graphics object called g in Graphics2d.

It is an example of polymorphism.

Basically the graphics 2d extends the graphics class in awt. Graphics itself is an abstract class, so it can't be created, it only defines some interface and some functionality.

Maybe the oracle API could help you:

http://docs.oracle.com/javase/7/docs/api/java/awt/Graphics.html http://docs.oracle.com/javase/7/docs/api/java/awt/Graphics2D.html

Upvotes: 0

MadProgrammer
MadProgrammer

Reputation: 347184

Presumably, g is a Graphics instance, Graphics2D g2 = (Graphics2D) g; is casting g to an instance of Graphics2D.

This is an example of Polymorphism in action...

Around Java 1.3/1.4 the new Graphics2D API was introduced into the Java API, but because most of the paint methods required Graphics, they weren't updated (for backwards compatibility). The developers however basically guaranteed that any system generated Graphics passed to these paint methods would get an instance of a Graphics2D context

Basically, Graphics2D is an extension to the Graphics API

Have a look at Painting in AWT and Swing and Performing Custom Painting for more details

Upvotes: 4

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