Convert Timestamp in Milliseconds to String Formatted Time in Java

It is common to represent timestamps in milliseconds in programming, but it’s often necessary to convert them into human-readable date and time formats for readability and presentation. Using the java.time package we can convert a timestamp in milliseconds to a string-formatted time in Java.

Read timestamp:

First, we need a timestamp in milliseconds. We can get this from the external source, i.e., the backend API, or from the user. We can also generate this using the following API, i.e., System.currentTimeMillis().

For example, let us assume we have a timestamp in milliseconds.

long timestampMillis = 1632156962000L;

Note: Replace the above timestamp with your own timestamp

Converting the timestamp

To convert the timestamp to a string-formatted time, we can use the Instant class from the java.time package. Following is the example:

import java.time.Instant;
import java.time.ZoneId;
import java.time.format.DateTimeFormatter;

public class TimestampToStringExample {

    public static void main(String[] args) {
        long timestampMillis = 1632156962000L; // Replace with your timestamp

        // Convert timestamp to Instant
        Instant instant = Instant.ofEpochMilli(timestampMillis);

        // Define the desired time zone
        ZoneId zoneId = ZoneId.of("America/New_York");

        // Format the Instant as a string
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")
                                                   .withZone(zoneId);
        String formattedTime = formatter.format(instant);

        System.out.println("Formatted Time: " + formattedTime);
    }
}

Explanation:

In the above example, we created an Instant object using Instant.ofEpochMilli(timestampMillis), which represents a point in time.

We defined the desired time zone using ZoneId. Please note, It’s important to specify the correct time zone to display the time in the intended region.

We format the Instant as a string using DateTimeFormatter. You can customize the format pattern as per your requirement.

In this example, we used “yyyy-MM-dd HH:mm:ss” to display the date and time in the format “YYYY-MM-DD HH:MM:SS.“

Customizing the Format

We can also customize the format pattern in the DateTimeFormatter as per our requirements. Here are some common format symbols.

• y: Year
• M: Month
• d: Day of the month
• H: Hour (0-23)
• m: Minute
• s: Second

For example, to display the date and time in a different format, such as “MM/DD/YYYY hh:mm a,” we can modify the pattern as shown below.

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("MM/dd/yyyy hh:mm a")
                                               .withZone(zoneId);