LocalDateTime ldt2 = LocalDateTime.now();
String year = ldt2.getYear()+"";
String month = ldt2.getMonthValue()+"";
String date = ldt2.getDayOfMonth()+"";
String hour = ldt2.getHour()+"";
String minute = ldt2.getMinute()+"";
String secs = ldt2.getSecond()+"";

试试这个,

SimpleDateFormat timeStampFormat = new SimpleDateFormat("yyyyMMddHHmmssSS");
Date myDate = new Date();
String filename = timeStampFormat.format(myDate);

LocalDateTime ldt2 = LocalDateTime.now();
String year = ldt2.getYear()+"";
String month = ldt2.getMonthValue()+"";
String date = ldt2.getDayOfMonth()+"";
String hour = ldt2.getHour()+"";
String minute = ldt2.getMinute()+"";
String secs = ldt2.getSecond()+"";

In Kotlin you can use this code : - 

Simple only need to change date format to this "dd-MM-yyyy" 
val d = Date()
val str: CharSequence = DateFormat.format("dd-MM-yyyy", d.getTime())
Log.e("", str.toString())
    
In Java You use this code: - 
    
Date date = new Date();
CharSequence str  = DateFormat.format("dd-MM-yyyy", date.getTime());
Log.e("Date", str.toString())

这与android无关，因为它是基于java的，所以你可以使用

private String getDateTime() { 
   DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
   Date date = new Date(); 
   return dateFormat.format(date); 
}

我已经用过这个了:

Date What_Is_Today=Calendar.getInstance().getTime();
SimpleDateFormat Dateformat = new SimpleDateFormat("dd-MM-yyyy");
String Today=Dateformatf.format(What_Is_Today);

Toast.makeText(this,Today,Toast.LENGTH_LONG).show();

首先我得到时间，然后我声明了一个简单的日期格式(以获得日期:19-6-2018) 然后我使用format将日期更改为字符串。