i dont know whats wrong whith this code but it gives me some errors.

the compiler says "cannot find symbol" on those lins:

*13)point = new Point3D(x,y,z);

*59)private java.lang.String toString()

*5) Point3D point;

public class Box3D extends java.lang.Object { double width,length,height; Point3D point; //Constructor overloading: private Box3D(double width, double length, double height) { this(0.0,0.0,0.0,width,length,height); } private Box3D(double x, double y, double z, double width, double length,double height) { point = new Point3D(x,y,z); if (width <= 0) { width = 1; } if (length <= 0) { length = 1; } if (height <= 0) { height = 1; } this.width = width; this.length = length; this.height = height; } //Methods: private double getVolume() { //Volume = (h)(w)(l) return (this.height * this.width * this.length); } private boolean isInside(double pointX, double pointY, double pointZ) { // if(!pointX<=x){return false;} if(!pointT<=y){ return false;} if(!pointZ<=z){ return false;} else {return true;} } private Point3D getCenter() { return ((this.height + this.width + this.length+this.x+this.y+this.z)/4); } private void move(double dx, double dy, double dz) { //Moves the box by the given delta values. this.point.x += dx; this.point.y += dy; this.point.z += dz; } private void scale(double factor) { //(Multiply all dimensions by //the specified factor). this.width *= factor; this.length *= factor; this.height *= factor; } private java.lang.String toString() { //"(x, y, z)->(width, length, height)". return "("+this.point.x + ","+this.point.y + "," + this.point.z + ") -> " + "(" + width + "," + length + "," + height + ")"; }}