Write an application that extends JPanel and displays diagonal lines in a square, like those in the last panel in Figure 16-43. Save the file as JDiagonalLinesPanel.java. a. Write an application that...

Write an application that extends JPanel and displays diagonal lines in a square, like

those in the last panel in Figure 16-43. Save the file as JDiagonalLinesPanel.java.

a. Write an application that extends JPanel and displays a yellow smiling face on the

screen. Save the file as JSmileFacePanel.java.

b. Add a JButton to the JSmileFacePanel program so the smile changes to a frown

and then back to a smile each time the user clicks the JButton. Save the file as

JSmileFacePanel2.java