Access Control
public class Point {
private float x , y ;
public Point() { x = y = 0 ;}
public Point(float a , float b) { x = a ; y = b;}
public void setX(float a) {x = a;}
public void setY(float a) {y = a;}
public float getX() {return x ;}
public float getY() {return y ;}
}