1. Change all of those "magic constant" Strings to meaningfully named constants. What the heck is "FLG"? 
 2. Then change all the meaningless action names. "Action.AC006" is not a useful name.
 3. Change the meaningless comments from "//20", "//30"... (unless these are somehow clear to somebody working on the project) They don't seem to match up with the ACxxx numbers.

Only then try some of the refactorings mentioned in the other answers. Refactoring garbage in leads to refactored garbage out. :-)

**And Another Thing Regarding OOP**

Other than the value of `tmp.b`, **all** of the if statements involve the **in** object. (Unless I missed one...) [Tell Don't Ask][1] (or see this [SO answer][2]) suggests that the `decide()` method, however it gets rewritten, be moved to the **in** object. e.g.

`public Action decideAction(String whateverTmpBReallyMeans);`

This may or may not make sense (or even be possible) in your project, but it's worth considering.


 [1]: https://martinfowler.com/bliki/TellDontAsk.html
 [2]: https://softwareengineering.stackexchange.com/questions/157526/explanation-on-how-tell-dont-ask-is-considered-good-oo