When you refer to someone as being a straight arrow what you mean is that he is an honest person or someone who follows all the laws.
Examples: “If you want to run a business, you can’t be a straight arrow.” * “Your friend Raja is not a straight arrow. I just don’t trust him.” * Most political parties avoid straight arrows.
The expression `straight shooter’ has the same meaning as `straight arrow’. Both are normally used in informal contexts.
Examples: ” We need to elect a straight shooter to office this time. This person needs to help us and not himself.” * Straight shooters don’t make good politicians.