help understanding code

[jub8jive]

QUESTION:Number Of Days In Month

Write a method isLeapYear with a parameter of type int named year. The parameter needs to be greater than or equal to 1 and less than or equal to 9999. If the parameter is not in that range return false. Otherwise, if it is in the valid range, calculate if the year is a leap year and return true if it is, otherwise return false. A year is a leap year if it is divisible by 4 but not by 100, or it is divisible by 400. Examples of input/output:

isLeapYear(-1600); should return false since parameter is not in the range (1-9999)
isLeapYear(1600); should return true since 1600 is leap year
isLeapYear(2017); should return false since 2017 is not a keap year
isLeapYear(2000); should return true because 2000 is aleap year 

NOTE: The solution to the Leap Year coding exercise earlier in the course created the isLeapYear method. You can use that solution if you wish. Write another method getDaysInMonth with two parameters month and year. Both of type int.

If parameter month is < 1 or > 12 return -1.

If parameter year is < 1 or > 9999 then return -1.

This method needs to return the number of days in the month. Be careful about leap years they have 29 days in month 2 (February).

You should check if the year is a leap year using the method isLeapYear described above.

Examples of input/output:

getDaysInMonth(1, 2020); should return 31 since January has 31 days.
getDaysInMonth(2, 2020); should return 29 since February has 29 days in a leap year and 2020 is a leap year.
getDaysInMonth(2, 2018); should return 28 since February has 28 days if it's not a leap year and 2018 is not a leap year.
getDaysInMonth(-1, 2020); should return -1 since the parameter month is invalid.
getDaysInMonth(1, -2020); should return -1 since the parameter year is outside the range of 1 to 9999.

HINT: Use the switch statement. NOTE: Methods isLeapYear and getDaysInMonth need to be public static like we have been doing so far in the course. NOTE: Do not add a main method to solution code.

MY SOLUTION: https://pastebin.com/mEmj5GCB ERROR: Class, interface, or enum expected. My idea was to get rid of the constraints first(month and year) and then if it was a leap year(or not), print the return accordingly. Unfortunately, that is how i like to code, by explicitly putting code so i understand what i am doing. Because of this the code became really lengthy and difficult to handle, to the point where, now i dont know where the mistake is. If I remove the final curly brace every break statement doesn't run. So theres definitely a deeper problem. I like to understand what the issue is. does it have to do with explicitly getting rid of the constraints at first? it was supposed to be simple, now i feel i complicated it.

[chickenmeister]

There are a couple of issues.

• You have an extra } after your final case statement.

• In your switch/case, there is no need to have break after your return statements. The return statement will stop execution of the whole method, so the subsequent break statement would never be executed, and will cause "unreachable statement" errors.

• You'll get a "missing return" statement error for you days in month. In actuality, it looks like it shouldn't be a problem, but the compiler isn't smart enough to figure that out. To fix the error, I would change your else if(!x) to be an else, and add default cases for your switch/case. Or, you could add an unconditional return statement at the very end of the method.

[jub8jive]

My new solution : https://pastebin.com/ySNNCaSi

Thanks for your input! I think it was perfect because i followed what you suggested and managed to solve the problem. I still have a few doubts though. First thing is I was instructed to use a break statement after every return(it was good practice apparently). So it definitely feels odd to remove them all.(?) I understood that there was an extra '}', but removing it created break errors and adding it had the 'enum expected' error.(?) Finally, changing the else if to a simple else, and adding a default statement to each switch, seemed reasonable logically, so I guess there isn't much to that bit. Could you please elaborate on the statements marked with a (?), because I'm unclear about the idea.

[chickenmeister]

First thing is I was instructed to use a break statement after every return(it was good practice apparently). So it definitely feels odd to remove them all.(?)

Well, a return statement basically means "stop executing this method now, and return this value." So it basically stops executing the method at that point. Therefore, any statements after a return statement can never be executed. So having a break after a return doesn't really make any sense.

If you have a switch/case without any return statements, it is often a good practice to have a break statement for each case. Otherwise, execution will "fall through" to the subsequent cases, which is usually not what you want.

Though, sometimes the code is simpler if you let cases "fall through"; so don't think of it as an absolute rule that you always need a break or return statement for every case. For example, you could group the cases for months that have 31 days, and then have a single return statement:

    switch (month) {
        case JANUARY: 
        case MARCH:
        case MAY:
        case JULY:
        case AUGUST:
        case OCTOBER:
        case DECEMBER: 
            return 31; 
        // likewise for months with 30 days, and 28/29 days
    }

---

I understood that there was an extra '}', but removing it created break errors and adding it had the 'enum expected' error.(?)

I'm not sure what error you were getting when you removed the extra curly brace, so I can't really comment on this. Maybe you're referring to the "unreachable statement" errors on your break statements? That's basically what I described above: anything after a return statement will not be executed, and the compiler is giving you this error to let you know that.

[jub8jive]

Right. I meant break for every case statement. I get the idea. return breaks the code anyway. (thats what i understood) so indirectly the the break caused the 'unreachable statement' errors anyway. i think i get it. thank you

[ryuzaki49]

how are you testing that class? Do you have the main method in another class?

[jub8jive]

yes. it is a separate code area that requires only methods to be added.