Can't change background of a JFrame with JScrollBar?

Hello everyone. I have a 'Grapher' class that extends JComponent that draws some rectangles. I wanted it to have a scrollbar, so I added an instance of the Grapher class into a JScrollBar, added the JScrollBar into a JFrame, and set the frame visible to see my rectangles. I didn't like the gray background so I figured I would be easily able to change it to another color, say red, but however I do this nothing works. Here is a part of my code:

Code:

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                        Grapher component = new Grapher();
                        component.setPreferredSize(new Dimension(1250, 500));
                        component.setBackground(Color.red);
                       
                       
                        JScrollPane scrollBar=new JScrollPane(component,JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS); 
                        scrollBar.setPreferredSize(component.getPreferredSize());
                       
                        scrollBar.setBackground(Color.red);
                       
                        JFrame viewFrame = new JFrame("Viewing Window");
                        viewFrame.setSize(1250, 500);
                        viewFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

                        viewFrame.add(scrollBar);
                        viewFrame.setLocationRelativeTo(null); //makes frame appear in center of screen
                       
                        viewFrame.getContentPane().setBackground(Color.red);
                       
                        viewFrame.setVisible(true);

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Moved from New to Java.

Please use meaningful variable names. That means, don't have a variable named scrollBar that refers to a JScrollPane.

Anything you see in a JScrollPane is the scroll pane's viewport view: in your code snippet, component. If the viewport view is transparent -- doesn't paint its background -- the background of the JScrollPane's JViewport will show. Not the background of the scroll pane nor that of the frame's content pane.

db

Thank you very much db, I was able to remove all of the other attempts at coloring the background and replaced it with a single line! I just called the scrollBar.getViewport() method and set the Viewport's color to Red. Thanks again