java.time.format.DateTimeFormatter class
java.text.SimpleDateFormat class
java.time.LocalDate class
java.time.LocalTime class
java.time.LocalDateTime class
java.time.Clock class
java.util.Date class
java.sql.Date class
java.util.Calendar class

java.time.format.DateTimeFormatter

import java.time.format.DateTimeFormatter;  
import java.time.LocalDateTime;    
public class CurrentDateTimeExample1 {    
  public static void main(String[] args) {    
   DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy/MM/dd HH:mm:ss");  
   LocalDateTime now = LocalDateTime.now();  
   System.out.println(dtf.format(now));  
  }    
}    

// output
2021/01/12 07:23:32

java.text.SimpleDateFormat

import java.text.SimpleDateFormat;  
import java.util.Date;  
public class CurrentDateTimeExample2 {  
public static void main(String[] args) {  
    SimpleDateFormat formatter = new SimpleDateFormat("dd/MM/yyyy HH:mm:ss");  
    Date date = new Date();  
    System.out.println(formatter.format(date));  
}  
}  

// output
12/01/2021 07:24:31

java.time.LocalDate

System.out.println(java.time.LocalDate.now());  

// output
2021-01-12

java.time.LocalTime

System.out.println(java.time.LocalTime.now());  

// output
07:25:18.447

java.time.LocalDateTime

System.out.println(java.time.LocalDateTime.now());  

// output
2021-01-12T07:25:49.922

java.time.Clock

System.out.println(java.time.Clock.systemUTC().instant());  

// output
2021-01-12T00:32:30.444Z

java.util.Date

java.util.Date date=new java.util.Date();  
System.out.println(date);  

// output
Tue Jan 12 07:26:49 ICT 2021

Example 2

long millis=System.currentTimeMillis();  
java.util.Date date=new java.util.Date(millis);  
System.out.println(date);  

// output
Tue Jan 12 07:31:25 ICT 2021

java.sql.Date

long millis=System.currentTimeMillis();  
java.sql.Date date=new java.sql.Date(millis);  
System.out.println(date);  

// output
2021-01-12

Date date=java.util.Calendar.getInstance().getTime();  
System.out.println(date);  

// output
Tue Jan 12 07:34:32 ICT 2021