RuleBasedCollator compare() method in Java with Example

The compare() method of java.text.RuleBasedCollator class is used to compare the strength of two objects and it will return 0, positive and negative value as an output according to the result.

Syntax:

public int compare(Object o1, Object o2)

Parameter: This method takes two objects between which comparison is going to take place.
Return Value: if the first object is equals, greater or lesser than the other object then it will return zero, positive and negative values respectively.
Exception: This method throws NullPointerException if one of the arguments is null.

Below are the examples to illustrate the compare() method:

Example 1:

Java

// Java program to demonstrate
// compare() method

import java.text.*;
import java.util.*;
import java.io.*;

public class GFG {
    public static void main(String[] argv)
    {
        try {

            // Creating and initializing
            // RuleBasedCollator Object
            RuleBasedCollator col
                = new RuleBasedCollator("< a< b< c< d");

            // Creating an initializing
            // object for comparison
            Object obj1 = "ab";

            // Creating an initializing
            // Object for comparison
            Object obj2 = "Ab";

            // compare both object
            // using compare() method
            int i
                = col.compare((String)obj1,
                              (String)obj2);

            // display result
            if (i < 0)
                System.out.println("ab is less than Ab");
            else if (i > 0)
                System.out.println("ab is greater than Ab");
            else
                System.out.println("ab is equal to Ab");
        }

        catch (ParseException e) {

            System.out.println(e);
        }
        catch (NullPointerException e) {

            System.out.println(e);
        }
    }
}

Output:

ab is less than Ab

Example 2:

Java

// Java program to demonstrate
// compare() method

import java.text.*;
import java.util.*;
import java.io.*;

public class GFG {
    public static void main(String[] argv)
    {
        try {

            // Creating and initializing RuleBasedCollator Object
            RuleBasedCollator col
                = new RuleBasedCollator("< a< b< c< d");

            // Creating an initializing
            // object for comparison
            Object obj1 = null;

            // Creating an initializing
            // Object for comparison
            Object obj2 = "Ab";

            // compare both object
            // using compare() method
            int i
                = col.compare((String)obj1, (String)obj2);

            // display result
            if (i < 0)
                System.out.println("ab is less than Ab");
            else if (i > 0)
                System.out.println("ab is greater than Ab");
            else
                System.out.println("ab is equal to Ab");
        }

        catch (ParseException e) {

            System.out.println(e);
        }
        catch (NullPointerException e) {
            System.out.println("one of the object is null");
            System.out.println(e);
        }
    }
}

Output:

one of the object is null
java.lang.NullPointerException

Reference: https://docs.oracle.com/javase/9/docs/api/java/text/RuleBasedCollator.html#compare-java.lang.String-java.lang.String-