CODEWITHSUNDEEP
javaswingawtgraphics2djava-2d
user3244786
user3244786

Reputation: 19

What does "Graphics2D g2d = (Graphics2D) g;" mean and what is the significance of this line in the following code segment?

public void paint(Graphics g) 
{
    Graphics2D g2d = (Graphics2D) g;
    g2d.setColor(Color.RED);
    g2d.fillOval(0, 0, 30, 30);
    g2d.drawOval(0, 50, 30, 30);        
    g2d.fillRect(50, 0, 30, 30);
    g2d.drawRect(50, 50, 30, 30);

    g2d.draw(new Ellipse2D.Double(0, 100, 30, 30));
}

Well, I am new to JPanel class and I have slight confusion. g is an object of Graphics class. So, what does (Graphics2D) g mean as in this line g seems as if it is a method and not an object? Further, can anyone tell me why Graphics2D class cannot be instantiated?

Upvotes: 0

Views: 5695

Answers (1)

k_g
k_g

Reputation: 4464

g is a variable, not a method. It is declared in the method declaration because it is a parameter of the method (i.e., it needs to be passed whenever the function is called).

The (Graphics2D) cast allows you to treat g as a Graphics2D object. See here for more information on casts.

You cannot initiate Graphics2D because it is an abstract class, meaning that it has some methods that are specific to implementation.

Upvotes: 4

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