Recursos de Datas no JAVA

package rosto.data;
import java.util.Calendar;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.*;


public class Data {
	Date hoje = new Date();

public String data(){
	String formato="dd/MM/yy";
	SimpleDateFormat formatada= new SimpleDateFormat(formato);
	return("Data de Hoje:"+formatada.format(hoje));
	}
	
public String dataMes(){
	String formato="dd/MM/yyyy";
	SimpleDateFormat form= new SimpleDateFormat(formato);
	return(""+form.format(hoje).substring(0,5));
	}
		
public String dataNormal(){
	String formato="dd/MM/yy";
	SimpleDateFormat formatada= new SimpleDateFormat(formato);
	return(""+formatada.format(hoje));
	}	
public String dataAniever(){
	int meses=hoje.getMonth()+1;
	String mes=""+meses;
	return mes;
	}	
	
	}

// Create a calendar object of the desired month
    Calendar cal = new GregorianCalendar(1999, Calendar.FEBRUARY, 1);
    
    // Get the number of days in that month
    int days = cal.getActualMaximum(Calendar.DAY_OF_MONTH); // 28
    
    // Try month in a leap year
    cal = new GregorianCalendar(2000, Calendar.FEBRUARY, 1);
    days = cal.getActualMaximum(Calendar.DAY_OF_MONTH);     // 29

Calendar Cal = Calendar.getInstance()