Java OCA OCP Practice Question 3238

Question

Consider the following class definition: 

class Point {
        private int x = 0, y;
        public Point(int x, int y) {
                this.x = x;
                this.y = y;
        }
        // DEFAULT_CTOR
}

Which one of the following definitions of the Point constructor can be replaced without compiler errors in place of the comment DEFAULT_CTOR? 

a)  public Point() {
            this(0, 0);
            super();
    }//w  w  w.jav a 2 s  .co m

b)  public Point() {
            super();
            this(0, 0);
    }

c)  private Point() {
            this(0, 0);
    }

d)  public Point() {
            this();
    }

e)  public Point() {
            this(x, 0);
    }



c)

Note

Options a) and b): Calls to super() or this() should be the first statement in a constructor, hence both the calls cannot be there in a constructor.

Option d): Recursive constructor invocation for Point() that the compiler would detect.

Option e): You cannot refer to an instance field x while explicitly invoking a constructor using this keyword.




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