How to get the current time in YYYY-MM-DD HH:MI:Sec.Millisecond format in Java?

Question

The code below gives me the current time. But it does not tell anything about milliseconds.

public static String getCurrentTimeStamp() {
    SimpleDateForm         


        

Answer 1

The easiest way was to (prior to Java 8) use,

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");

But SimpleDateFormat is not thread-safe. Neither java.util.Date. This will lead to leading to potential concurrency issues for users. And there are many problems in those existing designs. To overcome these now in Java 8 we have a separate package called java.time. This Java SE 8 Date and Time document has a good overview about it.

So in Java 8 something like below will do the trick (to format the current date/time),

LocalDateTime.now()
   .format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSS"));

And one thing to note is it was developed with the help of the popular third party library joda-time,

The project has been led jointly by the author of Joda-Time (Stephen Colebourne) and Oracle, under JSR 310, and will appear in the new Java SE 8 package java.time.

But now the joda-time is becoming deprecated and asked the users to migrate to new java.time.

Note that from Java SE 8 onwards, users are asked to migrate to java.time (JSR-310) - a core part of the JDK which replaces this project

Anyway having said that,

If you have a Calendar instance you can use below to convert it to the new java.time,

    Calendar calendar = Calendar.getInstance();
    long longValue = calendar.getTimeInMillis();         

    LocalDateTime date =
            LocalDateTime.ofInstant(Instant.ofEpochMilli(longValue), ZoneId.systemDefault());
    String formattedString = date.format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSS"));

    System.out.println(date.toString()); // 2018-03-06T15:56:53.634
    System.out.println(formattedString); // 2018-03-06 15:56:53.634

If you had a Date object,

    Date date = new Date();
    long longValue2 = date.getTime();

    LocalDateTime dateTime =
            LocalDateTime.ofInstant(Instant.ofEpochMilli(longValue2), ZoneId.systemDefault());
    String formattedString = dateTime.format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSS"));

    System.out.println(dateTime.toString()); // 2018-03-06T15:59:30.278
    System.out.println(formattedString);     // 2018-03-06 15:59:30.278

If you just had the epoch milliseconds,

LocalDateTime date =
        LocalDateTime.ofInstant(Instant.ofEpochMilli(epochLongValue), ZoneId.systemDefault());