In this exercise you will write and call a Java method to evaluate a degree 2 polynomial function. A degree 2 polynomial is an equation of the form

ax^{2}
+ bx + c

1) Open the **Polynomial.java** file which is in the **Polynomial** folder.

2) The first step is to complete the body
of the “for” loop in the *main* method.
Locate the following comment inside main:

// TO DO

// Call the polynomial method with argument x, and save the result in

// polynomialAtX

Add a line of source code which calls a method “polynomial”, passing in x as the method argument, and storing the return value in polynomialAtX. You will define the polynomial method in step 3.

3) Define the polynomial method. Find the comment:

// TO DO

// Define a method called polynomial which returns the value of the polynomial at

// its argument, x.

// Make use of the identity (ax + b)x + c = ax^2 + bx + c

// Declare the method as static.

and declare the polynomial method
immediately beneath it. We are going to make polynomial a *static*, or *class*, method
since we haven’t learnt about objects yet! To do this you need to add the
static modifier to your method declaration:

public static int polynomial( int x ) {

}

4) Inside the body of the polynomial
function, calculate the value of ax^{2} + bx + c, and return the result
as the return value of the method. The
constants a,b and c have already been defined for you at the top of the source
code.

5) Save and run the program. What is the value of the polynomial function when x = 5?

In this exercise you will use Eclipse to
create documentation for a Java class. Eclipse relies on an external tool (that
is provided by the JDK) called **javadoc**.
We will need to configure Eclipse to use this tool.

1) Open the **Circle.java** file which is in the **JavaDoc** folder. Look at the code and comments.

2) Since the JRE provided by Eclipse by default does not contain the javadoc tool, it is necessary to download and install a Java Developer Kit (JDK), which is freely available from the IBM Web site. However, IBM’s JDK has already been installed for this lab, so we can move onto the next step. The instructor will tell you where this has been installed.

3) To configure the Eclipse environment,
from the menu bar, select **Window**
-> **Preferences**. Expand the **Java** folder and select **Javadoc**. Enter the location of the
javadoc in the **Javadoc command** text
box. Click **OK** to apply the changes.

Now the Eclipse environment has been configured to use the javadoc tool to create documentation, we can specify exactly what documentation should be created.

4) We are only interested in generating
documentation for the classes in the **JavaDoc**
folder. Select the **JavaDoc** folder in
the **Package Explorer** view. From the
menu bar, select **File** -> **Export**.

This will display an “Export” dialog box.
Select **Javadoc** from the export
destination list and click **Next**.

We can decide which members will be documented. The javadoc tool will document members arranged by the following visibilities:

Private (all classes and all members)

Package (package, protected and public classes and members)

Protected (protected and public classes and members)

Public (only public classes and members)

For the purposes of this lab, select **Private**.

Take a note of
the destination. This is where Eclipse will generate the documentation. The
documentation could be created anywhere on the filesystem. However, to include
it within the **JavaDoc** folder,
replace the trailing **doc** with **JavaDoc\doc**.

Click **Finish** to complete the process and, if necessary, confirm that you
would like the javadoc location updating.

The results of this operation will be seen appearing in the console view.

5) The newly-created documentation will
appear in the **Package Explorer** view.
This documentation is more easily viewed in the **Resource Perspective**.

Click the **Resource Perspective** icon .

Expand **JavaDoc** -> **doc** to
reveal the documentation.

Look through these files to get an idea of what has been generated.

· packages.html lists all of the packages in the documented code. We didn’t declare any packages so our list is empty.

· Circle.html is the documentation for the circle class. Compare the generated documentation to the source file and see how the two compare.

· index.html displays a variety of methods for displaying the class and member information.

/**

* A Java application to calculate the value of a degree 2 polynomial

*/

class Polynomial {

// A polynomial of degree 2 in x is given by

// a x^2 + b x + c,

//

// Polynomial constants a,b and c: these can be accessed by any method of the

// class

private static final int a = 10;

private static final int b = 5;

private static final int c = -7;

/**

* Main method - prints a table of values for the polynomial

*/

public static void main(String[] args) {

int polynomialAtX;

for(int x = 0; x <= 10; x++) {

// TO DO

// Call the polynomial method with argument x, and save the result in

// polynomialAtX

polynomialAtX = polynomial(x);

System.out.println(x + "\t\t" + polynomialAtX);

}

} // end of main method

// TO DO

// Define a method called polynomial which returns the value of the polynomial at

// its argument, x.

// Make use of the identity (ax + b)x + c = ax^2 + bx + c

// Declare the method as static for now.

/**

* Calculate the polynomial function at x

*/

public static int polynomial(int x) {

int returnValue;

returnValue = (((a*x) + b) * x) + c;

return returnValue;

}

} // end of class

The output of the program is:

0 -7

1 8

2 43

3 98

4 173

5 268

6 383

7 518

8 673

9 848

10 1043