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Java String compareTo() Method with Example

Java String compareTo() Method: Here, we are going to learn about the compareTo() method with example in Java.
Submitted by IncludeHelp, on February 15, 2019

String compareTo() Method

compareTo() is a String method in Java and it is used to compare two strings (case-sensitive).

If both strings are equal – it returns 0, otherwise, it returns a value less than 0 or greater than 0 based on the first dissimilar characters difference.

Syntax:

    int string1.compareTo(string2);

Here, string1 and string2 are the strings to be compared, and it returns an integer value that is 0, less than 0 or greater than 0.

Example:

    Input: 
    str1 = "Hello world!"
    str2 = "Hello world!"

    Output:
    0

    Input: 
    str1 = "Hello world!"
    str2 = "HELLO WORLD!"

    Output:
    32

Java code to compare strings using String.compareTo() method

public class Main
{
    public static void main(String[] args) {
        String str1 = "Hello world!";
        String str2 = "Hello world!";
        String str3 = "HELLO WORLD!";
        
        System.out.println("str1.compareTo(str2) = " + str1.compareTo(str2));
        System.out.println("str1.compareTo(str3) = " + str1.compareTo(str3));
        System.out.println("str2.compareTo(str3) = " + str2.compareTo(str3));
        
        //checking with the condition
        if(str1.compareTo(str2)==0){
            System.out.println("str1 is equal to str2");
        }
        else{
            System.out.println("str1 is not equal to str2");
        }

        if(str1.compareTo(str3)==0){
            System.out.println("str1 is equal to str3");
        }
        else{
            System.out.println("str1 is not equal to str3");
        }        
        
        if(str2.compareTo(str3)==0){
            System.out.println("str2 is equal to str3");
        }
        else{
            System.out.println("str2 is not equal to str3");
        }                
    }
}

Output

str1.compareTo(str2) = 0
str1.compareTo(str3) = 32
str2.compareTo(str3) = 32
str1 is equal to str2
str1 is not equal to str3
str2 is not equal to str3