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MuscularMind@comic.com · Guest

Hi there,

I've just started an introductory to Java course, but I'm a tad behind
because I started the course a few weeks into the curriculum. This is
a bit embarrassing for me to admit, but I have no idea what one of my
assignments is asking for. Could someone help me.

Any help would be incredibly groovy.

Here's what the assignment is asking for:

1. Write a class called Train with the fields, constants, constructors
and methods outlined below.

2. Add Javadoc comments for the public class, fields, and methods.

Hand in a printout of the source code for the class. No need to hand in
the Javadoc documentation (the interface view), but PLEASE CHECK AND
MAKE SURE THAT EACH OF YOUR JAVADOC COMMENTS OCCUR AS EXPECTED IN THE
INTERFACE VIEW.

Please note: we will be using this class in Assignment 5.

fields

a private String field called name to hold the name of the train

private double fields as follow:

speed
xDirection
yDirection
xStartLocation
yStartLocation
xCurrentLocation
yCurrentLocation

constants

a public static constant named MAX_SPEED, with its value set to 55.0

public constructors

first constructor

parameters: a String called name, and three doubles called
xStartLocation, yStartLocation, and speed.
This constructor should set the values of the instance variables for
name, xStartLocation, yStartLocation
and speed to the values of the parameters. If the speed parameter is
less than 0, set the speed to 0, and if it is
greater than MAX_SPEED, set the speed to MAX_SPEED. xCurrentLocation
and yCurrentLocation should be set to the same values as xStartLocation
and yStartLocation

Second constructor:

Parameters: a String called name, and two doubles called xStartLocation
and yStartLocation.
This constructor should call the other constructor with a default value
of 0 for the speed.

public methods

Copy and paste the first three methods into your class. They contain
calculations for which you are not responsible.

Review each of these methods, as you will need to understand what they
do so that you can Javadoc comment them. They may also contain code
which will be useful for implementing other methods.

public void setDirection(double x, double y)
{
// the direction vector is stored internally in
// normalized form to simplify travel calculations

double d = Math.sqrt(x*x + y*y);
xDirection = x/d;
yDirection = y/d;
}

public void travel(int hours, int minutes)
{
double time = hours + minutes / 60.0;

xCurrentLocation += speed * time * xDirection;
yCurrentLocation += speed * time * yDirection;
}

public double computeDistanceTravelled()
{
// compute the distance between start location and current location

double x = xCurrentLocation - xStartLocation;
double y = yCurrentLocation - yStartLocation;

return Math.sqrt(x*x + y*y);
}

Write the rest of the methods described below the first three.

Method name: setSpeed
Parameters: a parameter named speed, data type double
Return type: void
Purpose: set the instance variable speed to the value of the parameter.
If the parameter is less than 0, set the train's speed to 0, and if
the parameter is greater than the constant MAX_SPEED, set the train's
speed to MAX_SPEED

Method name: stop
Parameters: none
Return type: void
Purpose: stop the train!

Method name: getSpeed
Parameters: none
Return type: double
Purpose: return the current speed of the train

Method name: computeDistanceApart
Parameters: a parameter of type Train called otherTrain
Return type: double
Purpose: calculate the distance between this train and otherTrain -
the calculation will look similar to the distance calculation in the
method computeDistanceTravelled() (if you aren't as excited about
math as I am, ask for some help with this method)

Method name: travel
Parameters: an int called minutes - the number of minutes the train
should travel
Return type: void
Purpose: computes the new location after travelling the number of
minutes in the parameter at the current speed for the train. This
method should convert the parameter to hours and minutes and call the
other travel method.

Method name: toString
Parameters: none
Return type: String
Purpose: Returns a formatted String of information about the train,
including its name, speed, start location and current location. When
printed, this String should print across several lines with easy to
read numbers. You can use the helper method fmt to display numbers
rounded to 2 decimal places.

private String fmt(double number)
{
DecimalFormat formatter = new DecimalFormat("###,##0.00");
return formatter.format(number);
}

Hand in a printout of the source code for the class. No need to hand in
the Javadoc documentation (the interface view), but PLEASE CHECK AND
MAKE SURE THAT EACH OF YOUR JAVADOC COMMENTS OCCUR AS EXPECTED IN THE
INTERFACE VIEW.

Michael Dunn · Guest

<standard reply>

the correct way to get help in forums/newsgroups like this is to post:
1) the specific problem you have
2) the code you have tried
3) the 'output you expect'
4) the 'output you get'
5) any relevant error messages

posting the assignment makes it look like just another
"do my homework for me" plea - even though that may not be your
intention.

Roedy Green · Guest

On 1 Nov 2005 16:32:10 -0800, [email]MuscularMind (AT) comic (DOT) com[/email] wrote, quoted or
indirectly quoted someone who said :

Bjorn Abelli · Guest

<MuscularMind (AT) comic (DOT) com> wrote...

[Follow-up set to comp.lang.java.help]

Take the assignment stepwise, and compile between each step, so you know
that you haven't introduced any errors in the latest step.

If you have errors, look carefully at the compiler's output to try to
understand why it occurs, before you attempt to correct them.

Mike Cocker · Guest

Wow, tough crowd. I'd give my pay cheque to see what you guys were like when
you were learning programming. It's almost like you guys wait for posts like
this so you can gang up on the guy. I agree that he should tackle it to some
degree. Maybe he has. I think everyone needs to lighten up. Here's an idea,
if you didn't want to help him, don't reply to the message. With that said,
"musclemind", let me look at this a bit more and I'll post soon.

"Roedy Green" <my_email_is_posted_on_my_website (AT) munged (DOT) invalid> wrote in
message news:9v9gm1928ijdaa20kdq1k6f0dcmnub669o (AT) 4ax (DOT) com...

Roedy Green · Guest

On Wed, 2 Nov 2005 18:07:00 -0500, "Mike Cocker"
<mcocker (AT) swandust (DOT) com> wrote, quoted or indirectly quoted someone who
said :

Roedy Green · Guest

On Thu, 03 Nov 2005 00:14:12 GMT, Mark Haase <mehaase (AT) gmail (DOT) com>
wrote, quoted or indirectly quoted someone who said :

Mike Cocker · Guest

Mike Cocker · Guest

Andrew Thompson · Guest

Mike Cocker wrote:

Tharpa · Guest

"Mike Cocker" <mcocker (AT) swandust (DOT) com> wrote