Corey Draper, 23, contacted the victims via Grindr, a mobile app favoured by gay, bi-sexual and bi-curious men, the Sydney District Court heard on Tuesday.

Draper used the app to locate potential victims in his area. After chatting online, the suggestion was made to meet up to use the drug ice.

At about 1.30am, on February 9, 2014, Draper met with a 28-year-old man in Waterloo, who handed over $200 to buy ice.

They walked to Buckland Street, Alexandria where Draper then pulled a knife and took the man's wallet, removing $270 cash, and mobile phone, before handing back the wallet. Draper threatened to kill him if the matter was reported to police.

The victim did call police and forensic investigators located Draper's DNA on the wallet.

The following day, at about 2am, Draper met up with a 48-year-old man he had been chatting to on Grindr.

The victim drove to Fountain Street, Alexandria, where Draper got in the car and threatened him with a knife, telling him to drive to McEvoy Street.

"Just do it or I will kill you. I have killed before," Draper said.

The victim managed to get away and contact police. Draper repeatedly rang the victim's mobile phone from his own phone. His DNA was found inside the victim's car.

He was arrested on February 13, 2014 and charged with robbery armed with an offensive weapon and being armed with intent to commit an indictable offence. He pleaded guilty in the local court last year.

In sentencing Draper, Acting Judge Gregory Hosking took into account a further offence of stealing that occurred on February 11, 2014. On that occasion, Draper stole cash, an ice pipe and a phone from the apartment of another man he met on Grindr.

Judge Hosking said Draper had a dysfunctional childhood, a criminal record and a serious drug habit that began at age 16. However, he said Draper had some prospects of rehabilitation as he has ambitions to become a bricklayer. Draper was supported in court by his girlfriend, who travelled from the Gold Coast to attend the hearing.

Judge Hosking sentenced Draper to a maximum of 33 months jail with a non-parole period of 17 months. With time served he will be eligible for parole on October 2.