Exception in thread "main" java.lang.ArrayIndexOutOfBoundsEx

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException:0 at Point.main(Point.java:15)
public class points {
protected int x,y;
public points(){setPoint(0,0);}
public points(int a,int b){setPoint(a,b);}
public void setPoint(int a ,int b){
x=a;
y=b;
}
public int getX(){return x;}
public int getY(){return y;}
public String toString()
{return "[" +x+","+y+"]";}
}
但是运行的时候不对……就是一行上面的字