The compareTo(Instant otherInstant) method of Instant class used to compare this instance to the instance passed as parameter to check whether both instances are equal. The comparison between both instances is based on the time-line position of the instants. The value to be returned by this method is determined as follows:
- if this instance is greater than instance passed as a parameter, then a positive value is returned
- if this instance is equal to the instance passed as a parameter, then a zero (0) is returned
- if this instance is less than instance passed as a parameter then a negative value is returned.
Syntax:
public int compareTo(Instant otherInstant)
Parameters: This method accepts a mandatory parameter otherInstant which is the other instant to be compared, and it should not be null.
Return Value: This method returns an integer value as follows:
- if this instance is greater than instance passed as a parameter, then a positive value is returned
- if this instance is equal to the instance passed as a parameter, then a zero (0) is returned
- if this instance is less than instance passed as a parameter then a negative value is returned.
Exception: This method throws NullPointerException if the otherInstant passed as the parameter is null.
Below programs illustrate the Instant.compareTo() method:
Program 1: When this instance is greater
// Java program to demonstrate// Instant.compareTo() method import java.time.*; public class GFG { public static void main(String[] args) { // create two instance objects Instant instant1 = Instant.parse("2018-10-20T16:55:30.00Z"); Instant instant2 = Instant.parse("2017-10-20T16:55:30.00Z"); // print Instant Values System.out.println("Instant1: " + instant1); System.out.println("Instant2: " + instant2); // compare both instant int value = instant1.compareTo(instant2); if (value > 0) System.out.println("Instant1 is greater"); else if (value == 0) System.out.println("Instant1 is equal to Instant2"); else System.out.println("Instant2 is greater"); }} |
Instant1: 2018-10-20T16:55:30Z Instant2: 2017-10-20T16:55:30Z Instant1 is greater
Program 2: When the otherInstant passed as parameter is greater
// Java program to demonstrate// Instant.compareTo() method import java.time.*; public class GFG { public static void main(String[] args) { // create two instance objects Instant instant1 = Instant.parse("2017-10-20T16:55:30.00Z"); Instant instant2 = Instant.parse("2018-10-20T16:55:30.00Z"); // print Instant Values System.out.println("Instant1: " + instant1); System.out.println("Instant2: " + instant2); // compare both instant int value = instant1.compareTo(instant2); if (value > 0) System.out.println("Instant1 is greater"); else if (value == 0) System.out.println("Instant1 is equal to Instant2"); else System.out.println("Instant2 is greater"); }} |
Instant1: 2017-10-20T16:55:30Z Instant2: 2018-10-20T16:55:30Z Instant2 is greater
Program 1: When both instances are equal
// Java program to demonstrate// Instant.compareTo() method import java.time.*; public class GFG { public static void main(String[] args) { // create two instance objects Instant instant1 = Instant.parse("2018-10-20T16:55:30.00Z"); Instant instant2 = Instant.parse("2018-10-20T16:55:30.00Z"); // print Instant Values System.out.println("Instant1: " + instant1); System.out.println("Instant2: " + instant2); // compare both instant int value = instant1.compareTo(instant2); if (value > 0) System.out.println("Instant1 is greater"); else if (value == 0) System.out.println("Instant1 is equal to Instant2"); else System.out.println("Instant2 is greater"); }} |
Instant1: 2018-10-20T16:55:30Z Instant2: 2018-10-20T16:55:30Z Instant1 is equal to Instant2
Program 4: Showing NullPointer Exception
// Java program to demonstrate// Instant.compareTo() method import java.time.*; public class GFG { public static void main(String[] args) { // create two instance objects Instant instant1 = Instant.parse("2018-10-20T16:55:30.00Z"); Instant instant2 = null; try { // compare both instant int value = instant1.compareTo(instant2); } catch (NullPointerException e) { System.out.println("Exception: " + e); } }} |
Exception: java.lang.NullPointerException
References: https://docs.oracle.com/javase/10/docs/api/java/time/Instant.html#compareTo(java.time.Instant)
