Date calculation

package com.parvez;

import java.util.Calendar;
import java.util.Date;

public class DatingWithDates {

public static void main(String[] args)
{
;
Date d1=new Date();
System.out.println("Today"+" "+d1.toString());
Calendar c=Calendar.getInstance();
c.setTime(d1);

displayDate("Date after a month",getDateNextMonth(d1));
displayDate("Date before a month",getDateLastMonth(d1));
displayDate("First date of last month",getDate_FirstDateOfLastMonth(d1));
displayDate("First date of next month",getDate_FirstDateOfNextMonth(d1));
displayDate("Last date of last month",getDate_LastDateOfLastMonth(d1));
displayDate("Last date of next month",getDate_LastDateOfNextMonth(d1));



}
public static void displayDate(String msg,Date d)
{
System.out.println(msg+" "+d.toString());
}
public static Date getDateNextMonth(Date di)
{
Calendar c=Calendar.getInstance();
c.setTime(di);
c.add(Calendar.MONTH,1);
Date dout=c.getTime();
return dout;
}

public static Date getDateLastMonth(Date di)
{
Calendar c=Calendar.getInstance();
c.setTime(di);
c.add(Calendar.MONTH,-1);
Date dout=c.getTime();
return dout;
}

public static Date getDate_FirstDateOfLastMonth(Date di)
{
Calendar c=Calendar.getInstance();
c.setTime(di);
c.add(Calendar.MONTH,-1);
c.set(Calendar.DAY_OF_MONTH, 1);
Date dout=c.getTime();
return dout;
}
public static Date getDate_FirstDateOfNextMonth(Date di)
{
Calendar c=Calendar.getInstance();
c.setTime(di);
c.add(Calendar.MONTH,1);
c.set(Calendar.DAY_OF_MONTH, 1);
Date dout=c.getTime();
return dout;
}

public static Date getDate_LastDateOfLastMonth(Date di)
{
Calendar c=Calendar.getInstance();
c.setTime(di);
c.set(Calendar.DAY_OF_MONTH, 1);
c.add(Calendar.DATE,-1);
Date dout=c.getTime();
return dout;
}
public static Date getDate_LastDateOfNextMonth(Date di)
{
Calendar c=Calendar.getInstance();
c.setTime(di);
c.add(Calendar.MONTH,2);
c.set(Calendar.DAY_OF_MONTH, 1);
c.add(Calendar.DATE,-1);
Date dout=c.getTime();
return dout;
}
}