How to compare 2 string in java Program -

public class LastIndexOfExample {
  public static void main(String args[]) {
    String s1 = "hello";
    String s2 = "hello";
    String s3 = "meklo";
    String s4 = "hemlo";
    System.out.println(s1.compareTo(s2));
    System.out.println(s1.compareTo(s3));
    System.out.println(s1.compareTo(s4));
  }
}

Here’s a step-by-step explanation of the program:

1. Class and Method Declaration:

public class LastIndexOfExample

{

public static void main(String args[])

{

The program declares a class named LastIndexOfExample.
The main method is the entry point of the program, where execution begins.

2. String Declarations:

String s1=”hello”;

String s2=”hello”;

String s3=”meklo”;

String s4=”hemlo”;

Four String variables are declared:

s1 is assigned the string “hello”.
s2 is assigned the string “hello”.
s3 is assigned the string “meklo”.
s4 is assigned the string “hemlo”.

3. compareTo() Method Calls:

System.out.println(s1.compareTo(s2));

System.out.println(s1.compareTo(s3));

System.out.println(s1.compareTo(s4));

compareTo() Method: The compareTo() method compares two strings according to lexicographical order, and returns:

0, if the two strings are the same.
A positive value when the first string is lexicographically greater than the second one.
A negative value when the first string is lexicographically smaller than the second one.

And now, let’s work through each of the comparisons:

1. s1.compareTo(s2)

s1 is “hello” and s2 is also “hello”.
Since both the strings are the same, s1.compareTo(s2) will return 0

2. s1.compareTo(s3)

s1 is “hello” and s3 is “meklo” .
s1: the first character is ‘h’, and its Unicode is 104. For s3, the first character is ‘m’, whose Unicode is 109.
In the comparison of s1.compareTo(s3), since lexicographically, ‘h’ appears before ‘m’, then s1.compareTo(s3) would return a value of negation; it would actually be -7, since there is a -7 difference of Unicode values, that between ‘h’, 104 and between ‘m’, 109.

Now let’s work on.

3. s1.compareTo(s4)

s1 is “hello” and s4 is “hemlo”.
The first two characters ‘h’ in both strings are the same.
The third character in s1 is ‘l’ (Unicode value 108) and in s4, it is ‘m’ (Unicode value 109).
Because ‘l’ is lexicographically less than ‘m’, s1.compareTo(s4) will return a negative value. It will return -1, because the Unicode difference between ‘l’ (108) and ‘m’ (109) is -1.

4. Output:

The System.out.println() statements will print the result of each comparison: