Java constructors of classes

Question

When I try to create a new instance of the class Point

Point nir = new Point(double x, double y);

I'm getting the error

Multiple markers at this line
   - x cannot be resolved to a variable 
   - y cannot be resolved to a variable

How come? I want x and y to be general, not specific. I want to include my Point as a field of a new class.

EDIT:

In a given class named Circle I want to replace the fields x0 and y0, that represent the coordinates of a point, with an object of type Point. So this is the begining of the class Circle that I want to refactor as above:

public class Circle {

   private double x0, y0, radius;

So, I basically want to change the representation of x0, y0 to Point structure.

Please read a basic Java tutorial, you are currently using Stack Overflow as your compiler. — Bombe
– Bombe, Commented Mar 25, 2011 at 19:36
@Nir, there is this small, insignificant, unknown site by a company named “Google.” You should look it up on Altavista. — Bombe
– Bombe, Commented Mar 25, 2011 at 19:55

templatetypedef · Accepted Answer · 2011-03-25 19:35:19Z

6

The error you're getting is that this code

new Point(double x, double y);

is not legal Java. When you create an object or call a function, you do not specify the types of the arguments. Instead, you just provide a value of that type. So, for example, you could create a point by writing

Point origin = new Point(0.0, 0.0);

Or

double x = 137.0;
double y = 2.71828;
Point myPoint = new Point(x, y);

Because in both cases the compiler already knows the types of the expressions you're providing as constructor arguments. You don't need to (and in fact should not) say that they're doubles.

Hope this helps!

answered Mar 25, 2011 at 19:35

templatetypedef

376k112 gold badges954 silver badges1.1k bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Andy Thomas · Accepted Answer · 2011-03-25 19:35:01Z

0

Try this:

Point nir= new Point(x, y);

If that doesn't work, show more code.

answered Mar 25, 2011 at 19:35

Andy Thomas

86.8k12 gold badges111 silver badges160 bronze badges

Comments

Rafe Kettler · Accepted Answer · 2011-03-25 19:35:09Z

0

You need to create the instance like so:

Point nir = new Point(x, y);

Or like so:

Point nir = new Point(15.0, 12.0);

where x and y are doubles. You're getting an error because you can't specify the type for arguments when calling a constructor, so Point nir = new Point(double x, double y); causes an error.

answered Mar 25, 2011 at 19:35

Rafe Kettler

77.1k21 gold badges160 silver badges151 bronze badges

Comments

Naftali · Accepted Answer · 2011-03-25 19:35:11Z

0

x and y have to already made:

so do:

Point nir = new Point(x, y);

answered Mar 25, 2011 at 19:35

Naftali

147k41 gold badges247 silver badges304 bronze badges

Comments

tvkanters · Accepted Answer · 2011-03-25 19:36:03Z

0

You're trying to set the parameters when it's expecting arguments. Try:

Point nir= new Point(x, y);

Or:

Point nir= new Point((double) x, (double) y);

answered Mar 25, 2011 at 19:36

tvkanters

3,5234 gold badges32 silver badges47 bronze badges

Collectives™ on Stack Overflow

Java constructors of classes

5 Answers 5

Comments

Comments

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

5 Answers 5

Comments

Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related