The compareTo() method of UUID class in Java is used to compare one UUID value with another specified UUID. It returns -1 if this UUID is less than the value, 0 if this UUID is equal to the value, and 1 if this UUID is greater than the value.
Syntax:
UUID_1.compareTo(UUID_2)
Parameters: The method takes one parameter UUID_2 to which the UUID_1 is to be compared.
Return Value: The method returns -1, 0 or 1 depending on whether this UUID_1 is less than, equal to or greater than the other UUID_2.
Below programs illustrate the working of compareTo() method:
Program 1: Checking if both the UUIDs are equal.
// Java code to illustrate compareTo() method  import java.util.*;  public class UUID_Demo {    public static void main(String[] args)    {          // Creating two UUIDs        UUID UUID_1            = UUID                  .fromString(                      "5fc03087-d265-11e7-b8c6-83e29cd24f4c");          UUID UUID_2            = UUID                  .fromString(                      "5fc03087-d265-11e7-b8c6-83e29cd24f4c");          // Displaying the UUID values        System.out.println("UUID_1: "                           + UUID_1.clockSequence());        System.out.println("UUID_2: "                           + UUID_2.clockSequence());          // Comparing both the UUIDs        System.out.println("Comparison Value: "                           + UUID_1.compareTo(UUID_2));    }} |
Output:
UUID_1: 14534 UUID_2: 14534 Comparison Value: 0
Program 2: When UUID_1 is less than UUID_2, the method returns -1.
// Java code to illustrate compareTo() method  import java.util.*;  public class UUID_Demo {    public static void main(String[] args)    {          // Creating two UUIDs        UUID UUID_1            = UUID                  .fromString(                      "58e0a7d7-eebc-11d8-9669-0800200c9a66");          UUID UUID_2            = UUID                  .fromString(                      "5fc03087-d265-11e7-b8c6-83e29cd24f4c");          // Displaying the UUID values        System.out.println("UUID_1: "                           + UUID_1.clockSequence());        System.out.println("UUID_2: "                           + UUID_2.clockSequence());          // Comparing both the UUIDs        System.out.println("Comparison Value: "                           + UUID_1.compareTo(UUID_2));    }} |
Output:
UUID_1: 5737 UUID_2: 14534 Comparison Value: -1
Program 3: When UUID_1 is greater than UUID_2, the method returns 1.
// Java code to illustrate compareTo() method  import java.util.*;  public class UUID_Demo {    public static void main(String[] args)    {          // Creating two UUIDs        UUID UUID_1            = UUID                  .fromString(                      "5fc03087-d265-11e7-b8c6-83e29cd24f4c");          UUID UUID_2            = UUID                  .fromString(                      "58e0a7d7-eebc-11d8-9669-0800200c9a66");          // Displaying the UUID values        System.out.println("UUID_1: "                           + UUID_1.clockSequence());        System.out.println("UUID_2: "                           + UUID_2.clockSequence());          // Comparing both the UUIDs        System.out.println("Comparison Value: "                           + UUID_1.compareTo(UUID_2));    }} |
Output:
UUID_1: 14534 UUID_2: 5737 Comparison Value: 1
