In Java, comparing two strings is the most common task in situations like file validation, user authentication, form input processing, and database queries.
While Java provides built-in methods like equals(), we can also create our own function to compare strings. A user-defined function allows us to compare strings without using built-in methods, which gives us more control over how the Program.
In this blog, we will learn how to use a user-defined function to compare two strings in Java with practical examples.
What is a User-defined function in Java?
A user-defined function in Java is a function created by the programmer instead of using built-in functions. It helps perform specific tasks by allowing you to write your own logic.
For example, instead of using Java’s built-in equals() method to compare strings, you can create your own function to check whether two strings are the same or not.
Here is the algorithm to create a user-defined function that compares two strings in Java:
- If either string1 or string2 is null, you should return false.
- If the lengths are different, return false because they can’t be the same.
- Loop through both strings, one letter at a time.
- If you find any different character, return false.
- If you go through the entire string without finding a difference, return true because the strings are the same.
Examples of using User-Defined Function to Compare Strings in Java
Let’s see some of the examples to compare strings using user-defined functions in Java:
Example 1: Compare Strings using user-defined functions in Java
In the below example, We will use a user-defined function to compare strings in Java.
Code:
Output:
Explanation: The above program defines a user-defined function areStringsEqual(), to compare two strings character by character.
Example 2: Case-Sensitive String Comparison using user-defined functions in Java
In Java, string comparisons are case-sensitive by default. This means “Hello” and “hello” are treated as different strings.
Code:
Output:
Explanation: In the above code, we have used a user-defined function to compare two strings in Java:
- areStringsEqual(str1, str2): It returns true because str1(“Coding”) and str2((“Coding”)) are same in the above code
- areStringsEqual(str1, str3): It returns false because str1(Coding) and str2(coding) both are of different cases.
Conclusion
In this blog, we have learned how we can use a user-defined function to compare two strings in Java. We explored an algorithm that checks for null values, compares string lengths, and iterates through each character to compare the strings.
If you want to be an expert in Java Programming language, you may refer to our Java Course.
Some Other Methods to Compare Strings in Java