Thread: Making a rectangle

So I am working on a hw assignment for a Java programming class and there is some slight confusion.

I am suppose to create a rectangle and I have created two classes; Rectangle.java and RectangleTester.Java.

So far my code for the class Rentangle.java is:

package edu.sbcc.hw2;

public class Rectangle {

private int width = 25;
private int height = 25;

public rectangle(int xcoord, int ycoord, int thewidth, int theheight) {
this.width = width;
this.height = height;

}

public int getWidth() {

return width;

So for my assignment I need two instance variables for height and width for which I have, but it says in the assignment I need methods (settings and getters /mutators and accessors that allow manipulation of my instance variables which is a little confusing. Do I put these methods on Rectangle.java or RectangleTester.java.

The same goes for the calculateArea, where am I suppose to put this?

Am I even on the right track with this assignment or am I way off? I DO NOT want anyone to right anything for me, I want to do it myself, I just need it explained a little better.

Please post your code correctly using code or highlight tags which are explained near the top of this link.

Setters and Getters are created for private member variables. You could google them to read more information on how these methods usually look like. A simple example would be:

public class Coord {
 
	private int x;
	private int y;
 
	public Coord(int x, int y) {
		this.x = x;
		this.y = y;
	}
 
	public void setX(int value) {
		x = value;
	}
 
	public int getX() {
		return x;
	}
 
	public void setY(int value) {
		y = value;
	}
 
	public int getY() {
		return y;
	}
 
}

This class has 2 private member variables and the apropriate Getters and Setters.

You would add them to the body of your Rectangle class.

You should really go over the basics once again before trying this program, there are countless errors in the program. Starting with misplaced semicolon and variables that have no type defined. You also removed your private member variables entirely and have closing curly brackets at wrong places.

Originally Posted by Jhop86

That's why I am asking for help... if someone can explain to me where I am making mistakes I can fix them. Saying you need to go over the basics again does not help... and countless errors? I count 7... I am new to this and just learning.

We would just be repeating what all the other tutorials and textbooks say because the errors you make are so basic there is not much more to say about them. I dont feel like repeating textbooks.

Did you review the links Norm provided in Post #7? Do you have any questions about the material presented there? Did you find an answer to the error you posted in Post #4?

Error: Main method not found in class edu.sbcc.hw2.RectangleTester, please define the main method as:
public static void main(String[] args)

Your code is missing closing curly brackets. Whenever you open them you also have to close them later on.
Besides that the error message is pretty much self-explanatory, is it not?

Figured it out, thanks for the help. If I have anymore questions I will ask.

--- Update ---

Well so far it is going really good, except I ran into another error while implementing constructors.

My new code is:

public class RectangleTester {
	private static void main(String[] args) {
 
		//instantiating the class
		Rectangle myFirstRectangle = new Rectangle(20, 50);
 
		//variable initialization
		myFirstRectangle.setLength (20);
		myFirstRectangle.setWidth (50);
 
 
		//print out
	System.out.println("Hey David! The area of my first rectangle with the dimensions:"+myFirstRectangle.getLength()+"*"+myFirstRectangle.getWidth());;
	System.out.println("is:"+myFirstRectangle.calcArea());
	}
}

The error is: Exception in thread "main" java.lang.Error: Unresolved compilation problem:
The constructor Rectangle(int, int) is not visible

at edu.sbcc.hw2.RectangleTester.main(RectangleTester. java:9)

When it says the constructor is not visible what does this mean?

If you write:

private Rectangle(int width, int length) {
...
}

Then the constructor has been declared "private" and can not be used by any other classes other then the Rectangle class.
You can use "public" instead to make the constructor visible to other classes.

For more information read over some of the very basic tutorials, it is explained there in great detail.

Wow, dumb mistake, thanks!

Now I am wrapping up the assignment, but I have one quick question.

The assignment says that I have to set all instance variables to private, how do I this and make them visible in the RectangleTester?

That's why it has been suggested that you improve your familiarity with THE BASICS. Most (if not all) of your errors are due to misapplying BASIC concepts. You have either not been paying attention to the details, or you haven't been practicing enough. Programming in any language is a skill and must be practiced before it can be confidently, accurately, and repeatably performed.

Originally Posted by Jhop86

The assignment says that I have to set all instance variables to private, how do I this and make them visible in the RectangleTester?

Thats what the Setters are for.

I had to change Width to Height and I had to change Length to Width, in doing so everything was fine except on my RectangleTester, on line 13 I have myFirstRectangle.setHeight(20);

It gives me these errors:

Exception in thread "main" java.lang.Error: Unresolved compilation problem:
The method setHeight(int) is undefined for the type Rectangl.

It also says this method is undefined for the type of rectangle. Can someone please elaborate?

--- Update ---

Figured it out