New Brunswick police say 44-year-old Tyrone Johnson of Newark also faces weapons charges stemming from Saturday night's confrontation.
Police say Johnson was riding a bicycle when he approached the students around 10:15 p.m. He showed them a silver handgun, which was later determined to be an imitation, and they turned over their cell phones and an undisclosed amount of cash.
Johnson rode off but was soon apprehended by police. A telephone number for Johnson could not be located Monday, and it was not known if he had retained an attorney.
The 21-year-old students, a Metuchen woman and a Westfield man, were not injured in the robbery.