Thread: Questions!

package javaapplication2;
class DayCounter{
public static void main(String[] arguments){
int yearIn = 2013;
int monthIn = 12;

if (arguments.length < 0)
monthIn = Integer.parseInt(arguments[0]);
if( arguments.length < 1)
yearIn = Integer.parseInt(arguments[1]);
System.out.println( monthIn + "/" + yearIn + " has "
+ countDays(monthIn, yearIn) + "days.");

}

This is just a part of the whole java file/program that I don't understand.
So my question is, what length are they referring to at:
if (arguments.length < 0)
if (arguments.length < 1) ?
Why did the person choose 0 and 1?


Also, what is "Integer.parseInt" and does (arguments[0] ) mean the monthIn will be stored in the "String[] arguments"?
If so, then what's the point of that?

monthIn = Integer.parseInt(arguments[0]);
yearIn = Integer.parseInt(arguments[1]);



I know that I have many questions, but please answer this question too:

When I type in statements and expressions in the main method, do they get stored inside the main method? (In the "String[] arguments" in this case)

Please answer my questions
I'm self-studying Java with a book that doesn't explain things very well.
Thanks!

Is there an input to this code in "main". This doesn't make much sense. This Java - parseInt() Method talks about parseInt.

I recommend "Head First Java" for an excellent book that you can buy used. I would like to see the rest of the program if it's not too big. thx.

package javaapplication2;
class DayCounter{
public static void main(String[] arguments){
int yearIn = 2013;
int monthIn = 12;

System.out.println( arguments.length );


if (arguments.length < 20000)
monthIn = Integer.parseInt(arguments[0]);
if( arguments.length < 2)
yearIn = Integer.parseInt(arguments[1]);
System.out.println( monthIn + "/" + yearIn + " has "
+ countDays(monthIn, yearIn) + "days.");

}

static int countDays(int month, int year) {
int count = -1;
switch (month) {
case 1:
case 3:
case 5:
case 7:
case 8:
case 10:
case 12:
count = 31;
break;
case 4:
case 6:
case 9:
case 11:
count = 30;
break;
case 2:
if ( year % 4 == 0 )
count = 29;
else count = 28;
if (( year % 100 == 0) & year % 400 !=0)
count = 28;
}

return count;


}
}