Everything looks right except the graphPath
parameter in your Request
method. Instead of:
"/" + pickedUsersId.get(0) + "/feed"
do:
pickedUsersId.get(0) + "/feed"
There should not be a leading slash "/" in front of your graph path. You can always refer to our documentation to see how exactly to publish to feed. https://developers.facebook.com/docs/howtos/androidsdk/3.0/publish-to-feed/