Java !! Please help

1. Declare (write) a Java interface with two methods, one that adds two doubles together returning the sum and one that multiplies two doubles together returning the product. Use descriptive identifiers. Include JavaDoc comments.

2. The iterator is the preferred mechanism to access the elements in a linked list. (See below for a quick summary of SimpleLinkedList.) Write the code for the interface java.util.Iterator, version1.7, that is, with three methods. You may ignore writing JavaDoc comments.

  public class SimpleLinkedList implements java.util.List { private Link first; private Link last; private int numElems; ... } class Link { Object item; Link next; ... }

3.

One of your colleagues is trying to create a component that draws concentric circles. Heres the code so far:

  import java.awt.*; import javax.swing.*; public class BullsEye extends JPanel { private static void draw(Color c, int x, int y, int r, Graphics g) { g.setColor(c); g.drawOval(x  r, y  r, 2*r, 2*r); repaint(); } public void paintComponent(Graphics g) { int x = getWidth() / 2; int y = getHeight() / 2; draw(Color.green, x, y, 50, g); draw(Color.red, x, y, 100, g); draw(Color.blue, x, y, 150, g); } }

10. This code doesn't work. What is the problem?

11. What is the effect of the following declaration?

import java.awt.*;