Javaで現在時刻を取得する3つの方法は何ですか

Date date = new Date();
SimpleDateFormat dateFormat= new SimpleDateFormat("yyyy-MM-dd :hh:mm:ss");
System.out.println(dateFormat.format(date));

Calendar calendar= Calendar.getInstance();
SimpleDateFormat dateFormat= new SimpleDateFormat("yyyy-MM-dd :hh:mm:ss");
System.out.println(dateFormat.format(calendar.getTime()));

Calendar cal=Calendar.getInstance();      
int y=cal.get(Calendar.YEAR);      
int m=cal.get(Calendar.MONTH);      
int d=cal.get(Calendar.DATE);      
int h=cal.get(Calendar.HOUR_OF_DAY);      
int mi=cal.get(Calendar.MINUTE);      
int s=cal.get(Calendar.SECOND);      
System.out.println("现在时刻是"+y+"年"+m+"月"+d+"日"+h+"时"+mi+"分"+s+"秒");