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From: Eric Sosman <esosman@comcast-dot-net.invalid>
Newsgroups: comp.lang.java.programmer
Subject: Re: in1To10
Date: Sat, 09 Aug 2014 16:13:29 -0400
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On 8/9/2014 3:12 PM, cdalten@gmail.com wrote:
> from the url
>
> http://codingbat.com/prob/p137365
>
> The problem states: "Given a number n, return true if n is in the range 1..10, inclusive. Unless "outsideMode" is true, in which case return true if the number is less or equal to 1, or greater or equal to 10."
>
> Here is what I came up with...
>
> public class In1to10 {
> 	static boolean in1To10(int n, boolean outsideMode) {
> 		
> 		if (outsideMode == false){
> 			if (n >= 1 && n <=10) {
> 				return true;
> 			}
> 		} else if (outsideMode == true){
> 			if (n <=1 || n >=10) {
> 				return true;
> 			}
> 		}
> 		
> 		return false;
> 	}
> 	public static void main(String[] args) {
> 		System.out.println(in1To10(5, false)); //true
> 		System.out.println(in1To10(11, false)); //false
> 		System.out.println(in1To10(11, true)); //true
> 	}//end main
> }
>
>
> Now upon googling the solutions, I saw some people use
> if(outsideMode == false)
> if(outsideMode == true)
>
> instead of using if(outsideMode == false)/else(outsideMode == true).
>
> Would both catch all the cases? If not, which one would?

     Since a `boolean' can represent only the two values `true'
and `false', it follows that

     - If it isn't `true' it must be `false', and

     - If it isn't `false' it must be `true'.

Therefore, you can write

	if (outsideMode == true) {
	    // Handle the `true' case
	} else {
	    // Look, Ma: No test!
	    // Handle the `false' case
	}

... using only one `if' test.  If the test succeeds you know
`outsideMode' is `true'.  If the test fails you know `outsideMode'
is *not* `true', hence (because of the limited possibilities for
a `boolean') it must be `false'.  Alternatively, you could write

	if (outsideMode == false) {
	    // Handle the `false' case
	} else {
	    // Look, Ma: No test!
	    // Handle the `true' case
	}

... by the same reasoning: If it's not `false', it must be `true'.

     A few additional hints:

     - It's seldom if ever worth while to compare a boolean value
       to a boolean constant.  Instead of `if (outsideMode == true)'
       just write `if (outsideMode)'.  Or, if you want to be perverse,
       write `if (outsideMode == true == true == true)' ...

     - Writing `if (something) return true; else return false;' is
       kind of silly, since `return something;' does the same thing.
       Similarly, `if (something) return false; else return true;'
       can be written as `return !something;'.

-- 
esosman@comcast-dot-net.invalid