Method called reverse that switches complex number coordinates.

Question

I have written a class called "Complex" and there are no errors in the program.
What I am confused about is how to answer an assigned question. The question
is this: "Write a method called reverse which will return a new complex number
with the coordinates reversed. That is, if the complex number which invokes
the method has coordinates (a,b), then the method should return a new complex
value with coordinates (b, a)."
I will include my code for the class here (I'm using the NetBeans IDE):
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package tutorial8;
* @author Aleks
public class Complex
    private int I; // Real Part
    private int J; // Imaginary Part
    public Complex(int I, int J)
    setComplex(I, J);
public int getI()
    return I;
public int getJ()
    return J;
public void setComplex(int I, int J)
this.I=I;
this.J=J;
if (I==J)
System.out.println("true");
else
System.out.println("false");
}thanks.

Answer 1

Your right it compiles without errors but it says it's missing a main method.
This main method thing is driving me insane. Some of my classes work such as the following
one:
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* and open the template in the editor.
package tutorial7;
* @author Aleks
import java.util.Scanner;
public class Shortcalculation
    public static void main(String[] args)
        Scanner keyboard = new Scanner(System.in);
        System.out.println("Enter a positive integer");
        int positiveInteger = keyboard.nextInt();
       if (positiveInteger < 2)
        System.out.println("First positive integer output");
        positiveInteger = 4;
        while ((positiveInteger/3 >=1) && (positiveInteger/3 < 2))
            System.out.println("4");
        else if (positiveInteger < 3)
        System.out.println("Second positive integer output");
        positiveInteger = 21;
        while ((positiveInteger/5 >=2) && (positiveInteger/5 < 3))
            System.out.println("21");
        else if (positiveInteger < 4)
        System.out.println("Third positive integer output");
        positiveInteger = 43;
        while (positiveInteger/7 <=3)
            System.out.println("43");
        else
        System.out.println("Not a valid integer");
}But I don't see why THIS one shouldn't. I try to include a "public static void main(string[] args)"
in the class complex but it says it's an illegal start of the expression. Maybe it depends on
where in the class I put it. I'm only practicing writing classes for 3-4 weeks now because I've read
a lot of the book. Too bad my memory is kind of bad. Ok, I have changed the class for this
question, I have added a reverse method. I did it without a return statement.
* To change this template, choose Tools | Templates
* and open the template in the editor.
package tutorial8;
* @author Aleks
public class Complex {
    private int I; // Real Part
    private int J; // Imaginary Part
    public Complex(int I, int J)
    setComplex(I, J);
    public int getI()
    return I;
public int getJ()
    return J;
public void setComplex(int I, int J)
this.I=I;
this.J=J;
if (I==J)
System.out.println("true");
else
System.out.println("false");
public void reverse()
this.I=J;
this.J=I;
}sorry for the long post.