CODEWITHSUNDEEP
java
user5550096
user5550096

Reputation:

How do I change my current code to check if the input was string type?

I want to check if the user inputed in a string, and if he does I want to print it out or warn him to enter a string next time. I know that my problem is with the condition in the if statement but I don't know which method I should use in this case. I use hasNextInt for Integers but from the look of it this doesn't work like I would hope with String.

EDIT: Just to clarify from the comments: the text should hold only a specific character set like a-z, A-Z and spaces.

import java.util.Scanner;

public class JavaLessonTwoTest {
    static Scanner userInput = new Scanner(System.in);

    public static void main(String[] args) {
        System.out.print("Enter string please: ");

        if (userInput.hasNext(String("")) {
            String stringEntered = userInput.next();
            System.out.println("You entered " + stringEntered);
        } else {
            System.out.println("Enter a string next time.");
        }
    }
}

Upvotes: 0

Views: 138

Answers (3)

Binkan Salaryman
Binkan Salaryman

Reputation: 3048

A console is a text interface, thus a user can only input data as String. Given that, you can try to parse the input to an Integer, Float, Book or any other type depending on your needs.

What you are trying to do is probably something like this:

while(true) {
    System.out.print("Enter string please: ");

    String input = userInput.next();

    boolean isInputInt;
    try {
        int number = Integer.parseInt(input);
        // parsing to int succeeded
        isInputInt = true;
    } catch (NumberFormatException ex) {
        // parsing to int failed
        isInputInt = false;
    }

    if (isInputInt) {
        System.out.println("Integers are not allowed.");
        // retry
        continue;
    } else {
        System.out.println("You entered " + input);
        // proceed
        break;
    }
}

Upvotes: 2

Paulo
Paulo

Reputation: 1498

What you probably are searching for, is a Regular Expression.
I'll give you an example, so you have to adapt it to your code:

public class Patt {
    public static void main(String... args) {
        String[] tests = {
        "AA A",
        "ABCDEFGH123",
        "XXXX123",
        "XYZabc",
        "123123",
        "X123",
        "123",
        };
        for (String test : tests) {
            System.out.println(test + " " + test.matches("[a-zA-Z ]*"));
        }
    }
}

The point is the regular expression

[a-zA-Z ]*

in the call test.matches("[a-zA-Z ]*"). It means "match only strings that have any number of letters which are either from a to z, A to Z or whitespace ().

Upvotes: 2

i23
i23

Reputation: 496

According to this: Restrict string input from user

This should work:

public static void main(String[] args) throws ParseException {
    Scanner sc = new Scanner(System.in);
    System.out.println("Please enter String only with letters:");
    while (!sc.hasNext("[A-Za-z]+")) {
        System.out.println("Digits are not allowed");
        sc.next();
    }
    String word = sc.next();
    System.out.println("User input was : " + word);
}

Upvotes: 0

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