PlayerCommandPreprocessEvent Problem

I'm not sure why this part of my code won't work. I am trying to make players only able to use /msg, /w, /t and /tell. I was debugging it and I couldn't figure out why it wouldn't work..

Code:

@EventHandler
public void onPreCommand(PlayerCommandPreprocessEvent event){
      
if (!event.getMessage().toLowerCase().startsWith("/msg")
                || !event.getMessage().toLowerCase().startsWith("/w")
                || !event.getMessage().toLowerCase().startsWith("/t")
                || !event.getMessage().toLowerCase().startsWith("/tell")) {
            event.setCancelled(true);
            }
        }

 

@MrSpyMan, Your issue is fairly stupid. You're trying to accept all but these values, correct?
All of the ors must be ands, || must be &&

 

@Tecno_Wizard I'm pretty sure it should be || because that means or... This is ment to check if the message is /msg or /w or /t or /tell. But I'm not sure why it's not working..

 

@MrSpyMan

He's right, it's DeMorgan's law.

 

@MrSpyMan, it's a lot more confusing than it seems.

So I am going to use the fake method foo() which returns a Boolean as an example.
Foo returns true if a innocuous condition is true.

So our if statement is if (foo() || foo1() || foo2())
If ONE of these is true in this case, ALL of them are true because an or statement will always return true if even one is true. So while foo() might be true, foo1() will be false, because it is not that command, making the final Boolean false. If you use and, all of them must be true for the final response to be true. If even one is false, the entire statement will be false.
Comprendre?

@mythbusterma, that's a law?

 

@Tecno_Wizard

His misguided thinking was something along the lines of "not (message is /msg or message is /w)," which he then incorrectly simplified to "not message is /msg or not message is /w" when, logically it is "not message is /msg and not message is /w." Look at the Wikipedia article: http://en.wikipedia.org/wiki/De_Morgan's_laws

 

@mythbusterma Thank you for the help! Besides De Morgan's Law is there anything other laws like that?

 

@MrSpyMan

Certainly, there's these laws which cover one proposition and the simplification thereof: http://en.wikipedia.org/wiki/Propositional_calculus#Basic_and_derived_argument_forms

Then there's the laws concerning more than one proposition, called the rules of inference:
http://en.wikipedia.org/wiki/List_of_rules_of_inference#Table:_Rules_of_Inference

 

@MrSpyMan wont your code make every other command not work?

Edit: Whoops, missed the word only.

 

@drpk Did you even read the first post...

 

Maybe try to set the priority to high?

 

@stoneminer02 No that's not the problem. Read the other replies.

 

I am not familiar with laws or anything from US/UK as of being from Norway.
Sorry.

 

@stoneminer02 This isn't anything to do with laws :S

 

I see alot of the talking about laws

 

Hahahahahaha you made my day!

 

@stoneminer02

We were talking about laws of logic and rules of inference......none of those have to do with the rule of law, at all. Really, read the posts.

 

@stoneminer02 I love you.

 

Love you too <3 :3