I was just wondering that if print task is available in ArcGIS JavaScript API 4.0 like 3.* or not.
No, not yet. See the functionality matrix for more information about which 3.x capabilities are not yet available in the 4.x API.
https://developers.arcgis.com/javascript/latest/guide/functionality-matrix/index.html
"Coming soon" it says. Can you give us a timeframe for when this will be available. We are also in need of a Directions widget as well.
Cheers,
Matt