About setting methods the right way

[dan kom]

Hello forums members. First i wondered if the code I've written is OK. Second, i wanted to know that if I'm gonna make a a setDate() method do i need to copy the whole block of code the constructor for each set-method i make for the date to be valid? (somthing tells me it's not the best way) ? thanks .


*I've not not finished the documentation yet, just the first constructor and the copy constructor.

/**
 * this class represents the dates in tour company 
 * 
 * 
 */

public class Date{
    /**
     * @param _x represent the x in the calendar
     */
    public int _day;   // CHANGE TO PRIVATE AFTER TESTING!
    public int _month;
    public int _year;
    private final int YEAR=2000;  
    private final int MONTH =1;
    private final int DAY = 1;
    
    public Date(int day, int month, int year){
        if (day>31 || day<0 || month<0 || month>12 || year <0){ //checks if date is valid
            _day = DAY;
            _month = MONTH;
            _year = YEAR;}
            
        else if ((month==2 && day>29) && ((year % 4==0 && !(year % 100==0)) || (year % 4==0 && year % 100==0 && year % 400==0))){ //checks if date is valid
            _day = DAY;
            _month = MONTH;
            _year = YEAR;}
            
        else if((month==2 && day>28) && !((year % 4==0 && !(year % 100==0)) || (year % 4==0 && year % 100==0 && year % 400==0))){//checks if date is valid
            _day = DAY;
            _month = MONTH;
            _year = YEAR;}
   
        else if(((month==4 || month==6 || month==9 || month==11) && day>30)){ //checks if date is valid
            _day = DAY;
            _month = MONTH;
            _year = YEAR;}
 
        else{                 //checks if date is valid
            _day = day;
            _month = month;
            _year = year;}
                  
        }
        
    public Date(Date other){
        _day = other._day;
        _month = other._month;
        _year = other._year;
    }
            }
        
        

[Liutauras Vilda]

Is it homework to do so?

Otherwise, have you found out that Java API already contains Date class as well as LocalDate class (since Java 8). You don't need to reinvent wheel, unless you have been told so.

[Liutauras Vilda]

And welcome to the Ranch

And something right from the beginning doesn't look ok with this code (for quite few reasons). But first, lets wait your answer to the question above.

[dan kom]

Yes it is homework we are need to do.2 constructors , 3 getMethods and 5 setMethods, all regarding dates.

[dan kom]

Liutauras Vilda wrote:And welcome to the Ranch

And something right from the beginning doesn't look ok with this code (for quite few reasons). But first, lets wait your answer to the question above.

Thanks, not my first time though ;D

[Liutauras Vilda]

dan kom wrote:Yes it is homework we are need to do.2 constructors , 3 getMethods and 5 setMethods, all regarding dates.

Alright. That is a very minimalistic information we could give some help on. In different words - we don't know what the instructions are. Either we need those, or we need to know what exact difficulties you're having with your code (regardless what kind of instructions are).

1. Without seeing exact question or instructions - I think you need to get rid of (fixed typo) those _______. Think about the other way to distinct variable names.
2. What is the point of the second constructor? Looks like a useless job. Like a date class within another date class (can't find the words to describe what it looks like). "I'll give you one apple so you'd have one to give me".

[dan kom]

Liutauras Vilda wrote:

dan kom wrote:Yes it is homework we are need to do.2 constructors , 3 getMethods and 5 setMethods, all regarding dates.

Alright. That is a very minimalistic information we could give some help on. In different words - we don't know what the instructions are. Either we need those, or we need to know what exact difficulties you're having with your code (regardless what kind of instructions are).

1. Without seeing exact question or instructions - I think you need to get rid off those _______. Think about the other way to distinct variable names.
2. What is the point of the second constructor? Looks like a useless job. Like a date class within another date class (can't find the words to describe what it looks like). "I'll give you one apple so you'd have one to give me".

we are told to use _x for the instance variables(just because they said ;P). not quite sure about the use of the second constructor, we are just at the beginning, so i think they just gave us stuff to do, even thought it doesn't look too practical.

As for the problem, we need to make setDate(day, month, year) method, now my question is that if i need to copy the entire block of code to make the date valid, or is there another way?

[Liutauras Vilda]

dan kom wrote:we are told to use _x for the instance variables

That is worse than I thought then.

dan kom wrote:not quite sure about the use of the second constructor, we are just at the beginning, so i think they just gave us stuff to do, even thought it doesn't look too practical.

That is the point - to do what? We don't know how to help until you tell us what you have been asked to do. And when you're not sure, you don't write stuff until you are (different from being mistaken).

So what is the task you have been given? Please give us wording of instructinos exactly as you were given.

dan kom wrote:now my question is that if i need to copy the entire block of code

If you catch yourself writing same code again, you stop and make it a method. Without even noticing you write same code again, all your code needs to be in a methods (small), so they would do only one job each.

[dan kom]

We are told to make a Date class and then as second question, a Trip class. Both of the will be used by a Tour Company. (i guess i will have to use the copy constructor on the second question).

The Date class would have int_day, int_month, int_year as instance variables.
it would have two constructors:
public Date(int day, int month, int year)

public Date(date other)


and it would have 6 methods: getDay(), getMonth(), getYear(), setDay(), setMonth(), setYear().

All dates must be valid according to Georgian calendar, that means 29/02/2013 doesn't exist for example(not a leap year).

[dan kom]

Liutauras Vilda wrote:
If you catch yourself writing same code again, you stop and make it a method.

So should i make boolean validDate() method? to check if date i valid then use it ? looks best to me, but i really hope i'm allowed to do that.

[Liutauras Vilda]

dan kom wrote:

Liutauras Vilda wrote:
If you catch yourself writing same code again, you stop and make it a method.

So should i make boolean validDate() method? to check if date i valid then use it ? looks best to me, but i really hope i'm allowed to do that.

Yes. If you need to validate something - you create a validation method. If your Date needs to be a valid Georgian date, so you create a method to check isValidGeorgianDate(). If you need to check if it is a leap year, you create a method isLeapYear(). If you're allowed or not try to ask your teacher. If you have been told to use '_x' for instance  variable, then we don't know what to expect further.

[dan kom]

Liutauras Vilda wrote:

dan kom wrote:

Liutauras Vilda wrote:
If you catch yourself writing same code again, you stop and make it a method.

So should i make boolean validDate() method? to check if date i valid then use it ? looks best to me, but i really hope i'm allowed to do that.

Yes. If you need to validate something - you create a validation method. If your Date needs to be a valid Georgian date, so you create a method to check isValidGeorgianDate(). If you need to check if it is a leap year, you create a method isLeapYear(). If you're allowed or not try to ask your teacher. If you have been told to use '_x' for instance  variable, then we don't know what to expect further.

thanks, i will ask the teacher. and btw, why _x is bad? is it a newbie thing? ;)

[Knute Snortum]

It's a convention thing.  Variable names should be in camelCase.