Java input validation: ways to implement it by using scanner

Are you an app and website developer? So Java is the most programming language you have known. In this blog, ArrowHiTech will give you some information about Java input validation and ways to implement it by using scanner. Thus can we start now?

What is Java input validation?

Validation is the process of verifying user input or database values to specific restrictions. Moreover, validation is used to shorten the time it takes for the application to run actual business logic. Then discover errors in user input. In the case of failure, the process improves performance and thus any further debugging sessions.

Furthermore, the Java Scanner class is used to collect user input. Because it includes multiple techniques for obtaining various types of input as well as validating the information. Therefore, in this article, we’ll look at some of the techniques that can be used to gather user input and validate it in Java.

Besides that, the code block that explains the methods is shown below.

import java.util.Scanner;

public class InputValidation {

    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);

        System.out.println(“Enter any text: “);

        while (!scanner.hasNext(“quit”)) {

            System.out.println(

                    scanner.hasNextInt() ? “The Input text is int: ” + scanner.nextInt() :

                            scanner.hasNextLong() ? “The Input text is long: ” + scanner.nextLong() :

                                    scanner.hasNextDouble() ? “The Input text is double: ” + scanner.nextDouble() :

                                            scanner.hasNextBoolean() ? “The Input text is boolean: ” + scanner.nextBoolean() :

                                                    “The Input text is String: ” + scanner.next());

        }

    }

}

An example of the Scanner class created in the above code block. The constructor takes an Input Stream parameter, such as System.in, and calls it with a new keyword.

Java input validation using Scanner class

Thus, different hasNextXXX() methods that used to perform different types of input validation.

Validate integer input using Scanner in Java

We can use the hasNextInt() function to see if the input is an integer, and then use the nextInt() method to get it.

For example:

Java input validation

Output:

Java input validation

Validate Floating point input using Scanner in Java

We used the hasNextDouble() function to validate floating-point numbers, which returns true if the input is of the floating type, and the nextDouble() method to acquire the user input.

For example:

Java input validation

Output:

Java input validation

Validate Boolean input using Scanner in Java

The hasNextBoolean() function can be used to determine whether the input is a valid boolean, and the nextBoolean() method can be used to obtain the input value.

For example

Java input validation

Output:

Java

Validate String input using Scanner in Java

We can use regex to acquire a string in a specified format to validate a string value. The hasNext() function used to validate a string that can only include alphabets using a regex. So let’s take a look at the example below.

Java language programming

Output:

app development

Conclusion

To conclude that, we have already mentioned all information about Java input validation. Thus, if you want to find out more about programming languages. So please click HERE to read more. 

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