Trouble with this if-statement

Question

I am coding in Java and using TextPad editor.

I am trying to write code that sets "r" equal to a certain value depending on whether the user is male or female. I have already asked the user to put "1" if they are male and "2" if they are female.

I have set r as a double. D, and weight have been defined by the user earlier in the code.

Here is the code that I am trying to use and it keeps giving me an error saying that I have not defined "r".

if (gender == 1) r = 0.73D; if (gender == 2) r = 0.66D; else System.out.println("Please enter 1 or 2 for male or female."); alcoholAbsored = (3.701*D)/(weight*r);

All of the code compiles until I get to the formula for alcoholAbsorbed and then tells me r is not defined. Technically there is no problem with the if/else statement when I compile but then when I try to use r there becomes a problem. I've ended up using this code for now but this is not really what I want because what if the user puts something other than 1 or 2?

if (gender == 1) r = 0.73D; else r = 0.66D; alcohol absorbed = (3.701*D)/(weight*r);

Can someone please tell me what I am doing wrong and how I might go about fixing it? Please and thank you!

Actually in your previous code the else part does not initialises the r. Thats why you are getting that error — Shahbaz Hashmi
– Shahbaz Hashmi, Commented Sep 21, 2016 at 3:25
But the value of r changes depending on whether the user enters 1 or 2 for male or female. r is not a static value. — Taylor Pearson
– Taylor Pearson, Commented Sep 21, 2016 at 3:26

afsafzal · Accepted Answer · 2016-09-21 03:23:15Z

The problem with your code is that in the first version, if it goes to the else block (which it will even if the user has entered 1) then r won't be initialized so at the next line it cannot find any value for it. The correct code would be something like this:

if (gender == 1) r = 0.73D; else if (gender == 2) r = 0.66D; else { r = -1D; System.out.println("Please enter 1 or 2 for male or female."); } if ( r != -1D) alcoholAbsored = (3.701*D)/(weight*r);

Or:

if (gender == 1 || gender == 2){ if (gender == 1) r = 0.73D; else r = 0.66D; alcoholAbsored = (3.701*D)/(weight*r); } else System.out.println("Please enter 1 or 2 for male or female.");

Do I need to put the alcoholAbsorbed formula in an if-statement?
No, but you just need to make sure that r has been initialized in all the possible branches that reach to alcoholAbsorbed.

Shahbaz Hashmi · Accepted Answer · 2016-09-21 05:38:42Z

Its better to code like this

if(gender==1 || gender==2) { if (gender == 1) r = 0.73D; else if (gender == 2) r = 0.66D; alcoholAbsored = (3.701*D)/(weight*r); // do something } else { System.out.println("Please enter 1 or 2 for male or female."); }

Hey TNT. I am posting it from my mobile. If the code is understandable. I think there is no need to shifting curly braces and scope statements.

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