How to Check if String contains only Numeric Digits in Java - Step by Step Examples

How to Check if String contains only Numeric Digits in Java ?

Answer

To check if a string contains only numeric digits in Java, you can use a regular expression or iterate through each character and check if it is a digit using the Character class methods.

✐ Examples

1 Check if String contains only Numeric Digits using regular expression

In this example,

We create a regular expression pattern that matches numeric digits only.
We use the matches method of the string object with the regular expression pattern to check if the string matches the pattern.
If the string contains only numeric digits, matchDigits will be true, otherwise false.
Finally, we print the result.

Java Program

// Using regular expression
public class Main {
    public static void main(String[] args) {
        String str1 = "12345";
        boolean matchDigits = str1.matches("\\d+");
        System.out.println("String contains only numeric digits: " + matchDigits);
    }
}

Output

String contains only numeric digits: true

2 Check if String contains only Numeric Digits using Character class methods

In this example,

We create a function containsOnlyNumericDigits that takes a string as input.
We iterate through each character of the string and check if it is a digit using the Character class methods.
If all characters are numeric digits, allDigits will be true, otherwise false.
Finally, we print the result.

Java Program

// Using Character class methods
public class Main {
    public static void main(String[] args) {
        String str2 = "12345";
        boolean allDigits = str2.chars().allMatch(Character::isDigit);
        System.out.println("String contains only numeric digits: " + allDigits);
    }
}

Output

String contains only numeric digits: true

Summary

In this tutorial, we learned How to Check if String contains only Numeric Digits in Java language with well detailed examples.

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How to Check if String contains only Numeric Digits in Java - Step by Step Examples

How to Check if String contains only Numeric Digits in Java ?

Answer

✐ Examples

1 Check if String contains only Numeric Digits using regular expression

Java Program

Output

2 Check if String contains only Numeric Digits using Character class methods

Java Program

Output

Summary

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