ANKARA, Turkey—A Turkish journalist, who is critical of President Recep Tayyip Erdogan’s government and has been living in exile in Germany, was injured after being attacked outside his home by three men who reportedly warned him to stop writing. Erk Acarer, a columnist for Turkey’s independent Birgun newspaper, said in a video posted on Twitter that the attack occurred late Wednesday in the courtyard of his home outside Berlin. He sustained some swelling on his head and was kept at a hospital for several hours for observation. Berlin police confirmed the assault, saying Acarer was attacked by several people on Wednesday evening in the Rudow district. In a video posted on Twitter, Acarer said that one of his attackers warned him in Turkish, “You will not write.” Earlier, the journalist posted a photograph of himself, saying he was attacked “with fists and knives.” “I know the attackers. I will never …