Add blogpost - How To Get Current Timestamp In Java?

Author: gauravkukade

_posts/java-time/2021-05-13-how-to-get-current-timestamps-in-java.md

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+---
+layout: post
+title: "How To Get Current Timestamp In Java?"
+author: gaurav
+categories: [Java, Java Time]
+description: "In this article, we will see how to get the current timestamp in Java."
+---
+In this article, we will see how to get the current timestamp in Java. 
+
+To get the current timestamp in Java, we can use [`java.time.Instant`](https://docs.oracle.com/javase/8/docs/api/java/time/Instant.html) from Java 8 and [`java.sql.Timestamp`](https://docs.oracle.com/javase/7/docs/api/java/sql/Timestamp.html) till Java 7.
+
+We check both [`java.time.Instant`](https://docs.oracle.com/javase/8/docs/api/java/time/Instant.html)  and [`java.sql.Timestamp`](https://docs.oracle.com/javase/7/docs/api/java/sql/Timestamp.html)  one by one.
+
+## 1. Using  `java.time.Instant` ( for Java 8)
+As per the [javadoc](https://docs.oracle.com/javase/8/docs/api/java/time/Instant.html),
+> This class models a single instantaneous point on the time-line. This might be used to record event time-stamps in the application. 
+
+I have given an example below that shows how to get the current timestamp using `java.time.Instant`  
+
+```java
+import java.sql.Timestamp;
+import java.time.Instant;
+import java.util.Date;
+
+/**
+ * A Java Program to get current timestamp using using the java.time.Instant
+ * 
+ * @author Gaurav Kukade at coderolls.com
+ *
+ */
+public class InstantExample {
+	
+	public static void main(String[] args) {
+	    
+		Instant instant = Instant.now();
+	    System.out.println("1. instant: "+ instant);    // 2021-05-13T15:05:18.734Z
+	    
+
+	    //convert date object to instant
+	    Date date = new Date();
+	    Instant instantFromDate = date.toInstant();
+	    
+	    System.out.println("2. instantFromDate: " +instantFromDate);  // 2021-05-13T15:05:18.873Z
+	    
+	    
+	    //get instnat from the java.sql.Timestamp
+	    Timestamp timestamp = new Timestamp(System.currentTimeMillis());
+	    Instant instantFromTimestamp = timestamp.toInstant();
+	    
+	    System.out.println("3. instantFromTimestamp: "+ instantFromTimestamp);  // 2021-05-13T15:05:18.874Z 
+	    
+	    //get the epoch timestamp in milliseconds 
+	    //epoch timestamp is number of milliseconds since January 1, 1970, 00:00:00 GMT
+	    Instant instant2 = Instant.now();  
+	    long timeStampMillis = instant2.toEpochMilli();
+	    
+	    System.out.println("4. timeStampMillis: "+ timeStampMillis);   // 1620918318874
+	    
+	    //get the epoch timestamp in seconds
+	    Instant instant3 = Instant.now();
+	    long timeStampSeconds = instant3.getEpochSecond();
+	    
+	    System.out.println("5. timeStampSeconds: "+ timeStampSeconds);   // 1620918318
+
+	}
+
+}
+```
+Output:
+```
+1. instant: 2021-05-13T15:24:19.907Z
+2. instantFromDate: 2021-05-13T15:24:19.988Z
+3. instantFromTimestamp: 2021-05-13T15:24:19.988Z
+4. timeStampMillis: 1620919459988
+5. timeStampSeconds: 1620919459
+```
+### Explanation:
+
+1. In the first case, we have used the `.now()` method of the `Instant` class to get the current timestamp.
+2. In the second case, we have created a new `date` object, and then we have used the `.toInstant()` on the `date` object to get the current timestamp.
+3. In the third case, we have created a new `timestamp` object using the system time in milliseconds. We can get the system time in millisecond using the `System.currentTimeMillis()`. To get the current timestamp (as instant) we have used the `.toInstant()` method on the `timestamp` object.
+4. In the fourth case, we are trying to get the epoch timestamp in milliseconds. We can get it using the `.toEpochMilli()` method on the `instant` object.
+5. In the fifth case, we are trying to get the epoch timestamp in seconds. We can get it using the `.getEpochSecond()` method on the `instant` object.
+
+## 2. Using  `java.sql.Timestamp` ( for Java 7 and below)
+
+```java
+import java.sql.Timestamp;
+import java.util.Date;
+
+/**
+ * A Java program to get the current timestamp using java.sql.Timestamp
+ * 
+ * @author Gaurav Kukade at coderolls.com
+ *
+ */
+public class TimestampExample {
+
+	public static void main(String[] args) {
+		
+		 //using system time in milliseconds
+	    Timestamp timestampFromSystemTime = new Timestamp(System.currentTimeMillis());
+	    System.out.println("1. timestampFromSystemTime: "+timestampFromSystemTime); // 2021-05-13 20:55:44.179
+	     
+	    //using java.util.Date
+	    Date date = new Date();
+	    Timestamp timestampFromDateObject = new Timestamp(date.getTime());	  
+	    System.out.println("2. timestampFromDateObject: " +timestampFromDateObject); // 2021-05-13 20:55:44.187
+
+	}
+
+}
+```
+Output:
+
+```
+1. timestampFromSystemTime: 2021-05-13 20:55:44.179
+2. timestampFromDateObject: 2021-05-13 20:55:44.187
+```
+
+### Explanation:
+
+1. In the first case, we are got the `timestamp` using the system time in milliseconds. We can get the system time in millisecond using the `System.currentTimeMillis()`.
+2. In the second case, we have created a new `date` object, and then we have used the `.getTime()` on the `date` object to get the current time in milliseconds. We have passed the time milliseconds to timestamp constructor to get the current timestamp.
+
+Sometimes we may need to convert the `java.time.Instant` to `java.sql.Timestamp` or vice versa. So let's see both conversions below.
+
+## How to convert `Instant` to `Timestamp` In Java?
+
+I have given an example below that converts the `java.time.Instant` to `java.sql.Timestamp` class.
+
+```java
+import java.sql.Timestamp;
+import java.time.Instant;
+
+/**
+ * A Java Program to convert java.time.Instant to java.sql.Timestamp
+ * 
+ * @author Gaurav Kukade at coderolls.com
+ *
+ */
+public class InstantToTimestamp {
+
+	public static void main(String[] args) {
+		
+		// get Timestamp from Instant 
+		Instant instant = Instant.now();
+	    Timestamp timestamp = Timestamp.from(instant);
+	    System.out.println("Instant To Timestamp: " +timestamp); // 2021-05-13 21:07:44.381
+
+
+	}
+
+}
+```
+
+Output:
+```
+Instant To Timestamp: 2021-05-13 21:07:44.381
+```
+### Explanation:
+
+In the above example, we have used `.from()` of the `Timestamp` class to get the current timestamp from the `instant` object.
+
+```java
+Timestamp timestamp = Timestamp.from(instant);
+```
+
+
+## How to convert `Timestamp` to `Instant` In Java?
+
+I have given an example below that converts the `java.sql.Timestamp` to `java.time.Instant` class.
+
+```java
+import java.sql.Timestamp;
+import java.time.Instant;
+
+/**
+ * A Java Program to convert java.sql.Timestamp to java.time.Instant
+ * 
+ * @author Gaurav Kukade at coderolls.com
+ *
+ */
+public class TimestampToInstant {
+
+	public static void main(String[] args) {
+		
+	    //get instnat from the java.sql.Timestamp
+	    Timestamp timestamp = new Timestamp(System.currentTimeMillis());
+	    Instant instant = timestamp.toInstant();
+	    System.out.println("Timestamp To Instant: " +instant); // 2021-05-13T15:39:08.046Z
+	    
+	}
+
+}
+```
+
+Output:
+```
+Timestamp To Instant: 2021-05-13T15:39:08.046Z
+```
+### Explanation:
+
+In the above example, we have used the `.toInstant()` method on the `timestamp` object to get the current timestamp (as Instant ).
+
+## Conclusion 
+
+We can get the current timestamp in java using the `Instant` and `Timestamp`.
+
+From Java 8, it is recommended to use the timestamp of the Instant class. We can get the current timestamp from `Instant`as is given below,
+
+```java
+Instant instant = Instant.now();
+
+//convert date object to instant
+Date date = new Date();
+Instant instantFromDate = date.toInstant();	    
+
+//get instnat from the java.sql.Timestamp
+Timestamp timestamp = new Timestamp(System.currentTimeMillis());
+Instant instantFromTimestamp = timestamp.toInstant();
+
+
+//get the epoch timestamp in milliseconds 
+//epoch timestamp is number of milliseconds since January 1, 1970, 00:00:00 GMT
+Instant instant2 = Instant.now();  
+long timeStampMillis = instant2.toEpochMilli();
+
+
+//get the epoch timestamp in seconds
+Instant instant3 = Instant.now();
+long timeStampSeconds = instant3.getEpochSecond();
+```
+
+In Java 7 or below, we can use the `Timestamp` class to get the current timestamp.
+
+```java
+ //using system time in milliseconds
+Timestamp timestampFromSystemTime = new Timestamp(System.currentTimeMillis());
+
+//using java.util.Date
+Date date = new Date();
+System.out.println(date.getTime());
+Timestamp timestampFromDateObject = new Timestamp(date.getTime());	  
+
+``` 
+Also we can convert the `java.time.Instant` to `java.sql.Timestamp` or vice versa.
+
+
+**Instant To Timestamp**
+
+```java
+Instant instant = Instant.now();
+Timestamp timestamp = Timestamp.from(instant);
+```
+
+**Timestamp to Instant**
+
+```java
+Timestamp timestamp = new Timestamp(System.currentTimeMillis());
+	    Instant instant = timestamp.toInstant();
+```
+
+That's it for now. 
+
+If you have any queries about the above article, please comment below. Thanks.
+
+We will see how to get the current date-time in java. Also, we will see how we can format them using the SimpleDateFormat.
+
+You can check my YouTube channel at: https://www.youtube.com/channel/UCl31HHUdQbSHOQfc9L-wo3w
+
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