Java related question

[alphamedical]

I hav question relating to JAVA programming. I tried to solve it by my self, but did'nt got it fully correct. So if you can, plz help me. The question is given below:



Write a static Java method named convertDate that takes THREE parameters representing the date, month and year.
The method should first validate the date and month eg. date should be from 1-31 for Jan, March, May, July, August, October and December and ranges from 1- 30 for the other months with the exception of Feb. If a year can be divided by 4, the month of Feb will have 29 days instead of 28 days.

Then convert and return the date as a string in the following format: DD/MM/YYYY short eg. 11/05/2002.
If any of the parameters are invalid the value “Invalid” should be returned.

Above is question which i am trying to solve. I have solved half of it which i am giving below,

class Dates
{

String date="MM/DD/YYYY";
public static boolean covertDate( int day,int month,int year)
{
switch(month)
{
case 1: case 3: case 5: case 7: case 8: case 10: case 12:
if(day<=31)
return true;
case 4: case 6: case 9: case 11:
if (day<=30)
return true;
case 2:
if (day<=28)
return true;
default:
return false;
} // end switch
} // end main
} // end class dates

Can anyone help me to solve this program. thanks in advance