### Question:
Force implements Direction, Updatable { @Override public int hashCode() { final int prime = 31; int result = 1; long temp; temp = Double.doubleToLongBits(fh); result = prime * result + (int) (temp ^ temp >>> 32); temp = Double.doubleToLongBits(fv); result = prime * result + (int) (temp ^ temp >>> 32); temp = Double.doubleToLongBits(sensibility); result = prime * result + (int) (temp ^ temp >>> 32); temp = Double.doubleToLongBits(velocity); result = prime * result + (int) (temp ^ temp >>> 32); return result; } Force();  Force(double fh, double fv);  Force(double fh, double fv, double velocity, double sensibility);  Force(Force force); static Force fromVector(double ox, double oy, double x, double y); void zero(); void setVelocity(double velocity); void setSensibility(double sensibility); void addDirection(double extrp, Direction direction); void addDirection(double extrp, double fh, double fv); void setDirection(Direction direction); void setDirection(double fh, double fv); void setDestination(double fh, double fv); void setDirectionMaximum(Direction max); void setDirectionMinimum(Direction min); double getVelocity(); double getSensibility(); boolean isDecreasingHorizontal(); boolean isIncreasingHorizontal(); @Override void update(double extrp); @Override double getDirectionHorizontal(); @Override double getDirectionVertical(); @Override int hashCode(); @Override boolean equals(Object object); @Override String toString();  }### Answer:
@Test void testHashCode() { final Force hash = new Force(1.0, 2.0, 3.0, 4.0); assertHashEquals(hash, new Force(1.0, 2.0, 3.0, 4.0)); assertHashNotEquals(hash, new Object()); assertHashNotEquals(hash, new Force(1.0, 2.0, 3.0, 1.0)); assertHashNotEquals(hash, new Force(1.0, 2.0, 1.0, 4.0)); assertHashNotEquals(hash, new Force(1.0, 2.0, 1.0, 1.0)); assertHashNotEquals(hash, new Force(1.0, 1.0, 3.0, 4.0)); assertHashNotEquals(hash, new Force(1.0, 1.0, 3.0, 1.0)); assertHashNotEquals(hash, new Force(1.0, 1.0, 1.0, 4.0)); assertHashNotEquals(hash, new Force(2.0, 2.0, 3.0, 4.0)); assertHashNotEquals(hash, new Force(2.0, 2.0, 3.0, 1.0)); assertHashNotEquals(hash, new Force(2.0, 2.0, 1.0, 4.0)); assertHashNotEquals(hash, new Force(2.0, 2.0, 1.0, 1.0)); assertHashNotEquals(hash, new Force(2.0, 1.0, 3.0, 4.0)); assertHashNotEquals(hash, new Force(2.0, 1.0, 3.0, 1.0)); assertHashNotEquals(hash, new Force(2.0, 1.0, 1.0, 4.0)); }