When working with graphics, we will need to import:
import java.awt.*;  
import javax.swing.*; 
The javax prefix is used to signify a package of Java extensions.

All of our drawings will occur in a JPanel.
A JPanel draws its content in the method public void paintComponent (Graphics g);
Each of the drawing components (such as those shown above) is capable of drawing itself, which will be done automatically. You will not be "calling" this method. This method will be called by the system.

In addition, we will include a call to super.paintComponent(g); which will prevent problems with drawing colors in relation to the background color.

//Method format for the drawing method:
public class DisplayGraphics extends JPanel
{
     public void paintComponent (Graphics g)
     {
          super.paint(Component(g);
          // the drawings occur here
     }

Now, in main:
     public static void main(String[ ] args)
     {
          //Establish the frame
          DisplayGraphics d = new DisplayGraphics( );
          JFrame f = new JFrame("Title of the frame");
          f.add(d); //adds DisplayGraphics to the frame for viewing
          f.setSize(400,400); //sets the coordinate size of frame
          f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //closes frame
          f.setLocationRelativeTo(null); //centers the frame on screen          
          f.setVisible(true); //makes frame appear on screen
     }
}

Comments:
You will notice that this example used
import java.awt.*;
import javax.swing.*;
While this general importing (*) of the entire package is not a problem in this program, it is considered more beneficial to import the specific methods needed for the program to save a bit of memory and avoid potential "overlap" problems (such as the Time method existing in more than one package).
import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;

FYI: The third line of this program gives a "Warning" referencing "serial UID".
The purpose of the serial UID is to forbid serialization and deserialization of the same classes in different versions, especially when there is not forward compatibility (eg. new version of the class cannot be serialized/unserialized by a previous definition).
This circumstance occurs rarely and is usually associated with projects by different authors that are interacting with one another. You can ignore this warning.