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Java Instant Class | compareTo() Method with Example

Instant Class compareTo() method: Here, we are going to learn about the compareTo() method of Instant Class with its syntax and example.
Submitted by Preeti Jain, on May 21, 2020

Instant Class compareTo() method

• compareTo() method is available in java.time package.
• compareTo() method is used to compare this Instant object to the given object.
• compareTo() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.
• compareTo() method may throw an exception at the time of comparing.
  NullPointerException: This exception may throw when the given parameter is null exists.

Syntax:

    public int compareTo(Instant ins);

Parameter(s):

• Instant ins – represents the object to be compared to this Instant.

Return value:

The return type of this method is int, it may return anyone of the given values,

• If (this Instant) < (Instant ins), it returns -1.
• If (this Instant) > (Instant ins), it returns 1.
• If (this Instant) == (Instant ins), it returns 0.

Example:

// Java program to demonstrate the example 
// of int compareTo() method of Instant

import java.time.*;
public class CompareOfInstant {
    public static void main(String args[]) {
        // Instantiates two Instant
        Instant ins1 = Instant.parse("2006-04-03T05:10:15.00Z");
        Instant ins2 = Instant.parse("2007-06-05T10:20:30.00Z");

        // Display ins1,ins2
        System.out.println("Instant ins1 and ins2: ");
        System.out.println("ins1: " + ins1);
        System.out.println("ins2: " + ins2);

        System.out.println();

        // Here, this method compares this Instant
        // (ins1) to the given Instant(ins2) i.e.
        // here it returns -1 because ins1 < ins2
        int compare = ins1.compareTo(ins2);

        // Display compare
        System.out.println("ins1.compareTo(ins2): " + compare);

        // Here, this method compares this Instant
        // (ins1) to the given Instant(ins1) i.e.
        // here it returns 0 because ins1 == ins1
        compare = ins1.compareTo(ins1);

        // Display compare
        System.out.println("ins1.compareTo(ins1): " + compare);

        // Here, this method compares this Instant
        // (ins2) to the given Instant(ins1) i.e.
        // here it returns 1 because ins1 > ins2
        compare = ins2.compareTo(ins1);

        // Display compare
        System.out.println("ins2.compareTo(ins1): " + compare);
    }
}

Output

Instant ins1 and ins2: 
ins1: 2006-04-03T05:10:15Z
ins2: 2007-06-05T10:20:30Z

ins1.compareTo(ins2): -1
ins1.compareTo(ins1): 0
ins2.compareTo(ins1): 1