Jarrod James Lodge, now aged 19, pleaded guilty to armed robbery and was given a suspended prison sentence in the Supreme Court in Launceston on Tuesday.

The court heard Lodge placed the groceries into a trolley at Coles in Kings Meadows about 7.50pm on September 7 before asking a staff member if the fire escape would open.

When told it could not, Lodge produced a knife and threatened multiple Coles staff members who moved behind a pallet jack.

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Lodge then forced the door open and left with the trolley, but was followed by staff and abandoned the groceries outside and fled on foot. All of the groceries were recovered.

Lodge was identified on CCTV and arrested on September 19, admitting the offending to police.

In the police interview, Lodge said he intended to steal food because he was "starving", and decided to get a fortnight's worth. He said his methamphetamine habit "cost a fair bit" and he intended to sell some of the food to fund his habit.

He did not recall threatening the staff members.

Lodge also confessed to setting fire to a stolen car at Hollybank on May 18.

The court heard Lodge became homeless after "very difficult circumstances" resulted in him moving out of home. He was offered methamphetamine and quickly became addicted, spending most nights sleeping under an overpass.

Lodge has since reconciled with his family and is addressing his addiction.

Acting Justice Brian Martin said the offending was "out of character" and was a response to Lodge's difficult situation at the time.

"You should understand that armed robbery, particularly of vulnerable people in stores, is too common in our community and causes great stress to those involved," he said.

"It is apparent to me that you deeply regret what you have done and you are distressed by the circumstances in which you have found yourself."

Acting Justice Martin said it was in the community's interests to keep young offenders out of jail, but Lodge was on his final warning.

He was convicted and sentenced to two years and three months in prison, suspended for two years. He was also placed on an 18-month community corrections order including 100 hours of community service and drug testing.