He couldn't stand the death of Johnny so he committed suicide by running from the police and holding up a gun to threaten them. The fuzz thought the gun was loaded so the filled him with bullets.
dally dies them same night as johnny, when johnny dies dally has so much pain that he robs a store IMMENDIANTLY after johnny dies and get shot by the police.
In the beginning of the book, it doesn't seem like Dally would be the person who wanted to die. But, at the end of the book, when the cops shot him, he was happy. He was happy because the world took...