The Shape.contains() method allows a Shape implementation to conservatively return false when:

• the intersect method returns true and
• the calculations to determine whether or not the Shape entirely contains the rectangular area are prohibitively expensive.

• 
  the intersect method returns true and
  
• 
  the calculations to determine whether or not the
  Shape entirely contains the Rectangle2D
  are prohibitively expensive.
  

Only SEG_MOVETO, SEG_LINETO, and SEG_CLOSE point types will be returned by the iterator.

The amount of subdivision of the curved segments is controlled by the flatness parameter, which specifies the maximum distance that any point on the unflattened transformed curve can deviate from the returned flattened path segments. An optional AffineTransform can be specified so that the coordinates returned in the iteration are transformed accordingly.
Returns: a PathIterator object that provides access to the Shape object's flattened geometry.
Parameters:
- at - an optional AffineTransform to be applied to the coordinates as they are returned in the iteration, or null if untransformed coordinates are desired.
- flatness - the maximum distance that the line segments used to approximate the curved segments are allowed to deviate from any point on the original curve
Since: 1.2

The Shape.intersects() method allows a Shape implementation to conservatively return true when:

• there is a high probability that the rectangular area and the Shape intersect, but
• the calculations to accurately determine this intersection are prohibitively expensive.

• 
  there is a high probability that the Rectangle2D and the
  Shape intersect, but
  
• 
  the calculations to accurately determine this intersection
  are prohibitively expensive.