Java获取系统时间

import java.text.SimpleDateFormat;
import java.util.Date;

public class k27 {
public static void main(String[] args){
Date date=new Date();
SimpleDateFormat df=new SimpleDateFormat("yyyy-mm-dd hh:mm:ss");
String str=df.format(date);
System.out.println(str);
int a=Integer.parseInt(str);
switch(a){
case 0:
case 1:
case 2:
case 3:
case 4:
case 5:
case 6:
System.out.println("你好，现在是凌晨");
break;
case 7:
case 8:
case 9:
case 10:
case 11:
case 12:
System.out.println("你好，现在是上午");
break;
case 14:
case 15:
case 16:
case 17:
case 18:
System.out.println("你好，现在是下午");
break;
}
}
}