Australian journalist Peter Greste, a former cellmate of Ibrahim Halawa, says there will be no return to normal for the Dublin man when he is released.
"You can't go back. It is not an option to pick up where you left off. He will realise that there was a point to all this and will have to turn it into something positive," Mr Greste told RTÉ's Morning Ireland.
Ibrahim Halawa, from Firhouse, was aquitted of all charges on Monday after spending four years in prision in Cairo, Egypt.
He was arrested in August 2013 along with his sisters Somaia, Fatima and Omaima during protests against the ousting of then president Mohammed Morsi.
The three women had been released on bail in November 2013 and had long since returned to Dublin, while their brother remained behind bars awaiting trial.
Mr Greste said that he became aware of Mr Halawa’s acquittal in a “flurry of tweets”.
“It is absolutely extraordinary news. It has been far too long. It made my day.”
He said he was surprised to hear of the acquittal after so many set backs and adjournments.
He had been concerned that Mr Halawa would face the same fate as he had and would have been convicted, even though there was no evidence, because the authorities felt they had to make a point.
“I always felt he was innocent.”
Mr Greste dismissed questions that have arisen about Mr Halawa's connection to the Muslim Brotherhood.
“Those questions are ridiculous. He was a young idealistic man, exercising his democratic right for what he believed in. He did nothing wrong.
“Such questions are spurious, they are ridiculous.”
He said that Mr Halawa had no association with the Muslim Brotherhood and the authorities had not been able to prove that.
He also warned that Mr Halawa will find it very difficult to adjust to freedom. “There is a desire to get back to normal, but there is no such thing as normal.”