When you get the graphic context from JPanel get null, why?

[Anderson]

So, the question is, why are you referring to Graphics zero?

package CardGame;
import javax.swing.SwingUtilities;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.BorderFactory;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
public class Testing {

public static void main(String[] args) {

SwingUtilities.invokeLater(new Runnable(){

public void run(){

createAndShowGUI();

}

});

}
private static void createAndShowGUI() {
    Tr.db("Created GUI on EDT?"SwingUtilities.isEventDispatchThread()); 
    JPanel p = new JPanel();
    JFrame f = new JFrame("Swing PaintDemo");
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    p.setOpaque(true);
    p.setBackground(Color.red);
    Graphics g = p.getGraphics();
    //вот здесь вылетает исключение нул пойнт ексепшн
    //при попытке на панели что нить написать
    g.drawString("hello", 10, 50);
    f.add(p);
    f.pack();
    f.setVisible(true);
}

}

[elysha]

You have a code. p.getGraphics() returns null♪ The thing is, f.setVisible(true) After him. Nothing yet, getGraphics() I'll be back. null♪ Must be like that.

private static void createAndShowGUI() {
    JPanel p = new JPanel();
    JFrame f = new JFrame("Swing PaintDemo");
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
p.setOpaque(true);
p.setBackground(Color.red);
f.add(p);
f.setVisible(true);
f.pack();
Graphics g = p.getGraphics();
g.drawString("hello", 10, 50);

}