Character isDigit() method in Java with examples

Last Updated : 17 May, 2020

The java.lang.Character.isDigit(char ch) is an inbuilt method in java which determines whether a specified character is a digit or not. There are few conditions that a character must accomplish to be accepted as a digit. That is if the general category type of a character, provided by Character.getType(ch), is DECIMAL_DIGIT_NUMBER, then the character is a digit. Some Unicode character ranges that contain digits:

From '\u0030' to '\u0039' : ISO-LATIN-1 digits ('0' through '9') From '\u0660' to '\u0669' : Arabic-Indic digits From '\u06F0' to '\u06F9' : Extended Arabic-Indic digits From '\u0966' to '\u096F' : Devanagari digits From '\uFF10' to '\uFF19' : Fullwidth digits

Apart from the above mentioned ranges, many other character ranges contain digits as well. Syntax:

public static boolean isDigit(char ch)

Parameter: This method accepts character parameter ch as an argument, which is to be tested. Return value:This method returns a boolean value. It returns True if ch is digit, else False. Note: This method cannot handle supplementary characters. To support all Unicode characters, including supplementary characters, use the isDigit(int) method. Below programs illustrate the above method: Program 1:

Java

// Java program to illustrate the
// Character.isDigit() method

import java.util.*;
import java.lang.*;

public class GFG {

    public static void main(String[] args)
    {

        // two characters
        char c1 = 'A', c2 = '4';

        // Function to check if the character
        // is digit or not
        System.out.println(
            c1 + " is a digit -> "
            + Character.isDigit(c1));
        System.out.println(
            c2 + " is a digit -> "
            + Character.isDigit(c2));
    }
}

Output:

A is a digit -> false
4 is a digit -> true

Program 2:

Java

// Java program to illustrate the
// Character.isDigit() method

import java.util.*;
import java.lang.*;

public class GFG {

    public static int search_digit(String s)
    {

        // Function to check if is digit
        // is found or not
        for (int i = 0; i < s.length(); i++) {
            if (Character.isDigit(
                    s.charAt(i))
                == true) {
                // return position of digit
                return i + 1;
            }
        }
        // return 0 if digit not present
        return 0;
    }

    public static void main(String[] args)
    {

        // Array of strings
        String[] arr = { "ABC4DEF", "QWERTY" };

        // To store the position of digit
        int index = 0;

        // Traverse the array arr[] to find digit
        // within it's elements
        for (String x : arr) {
            index = search_digit(x);
            if (index != 0) {
                System.out.println(
                    "Digit found at : "
                    + (index)
                    + "th position.");
            }
            else {
                System.out.println(
                    "Digit not present.");
            }
        }
    }
}

Output:

Digit found at : 4th position.
Digit not present.

The java.lang.Character.isDigit(int codePoint) is an inbuilt method in java which determines whether the specified Unicode code point character of integer type is a digit or not. There are few conditions that a character must accomplish to be accepted as a digit. That is if the general category type of a character, provided by getType(codepoint), is a DECIMAL_DIGIT_NUMBER, then the character is a digit. Some Unicode character ranges that contain digits:

From '\u0030' to '\u0039' : ISO-LATIN-1 digits ('0' through '9') From '\u0660' to '\u0669' : Arabic-Indic digits From '\u06F0' to '\u06F9' : Extended Arabic-Indic digits From '\u0966' to '\u096F' : Devanagari digits From '\uFF10' to '\uFF19' : Fullwidth digits

Apart from the above mentioned ranges, many other character ranges contain digits as well. Syntax:

public static boolean isDigit(int codePoint)

Parameter: This method accepts unicode character parameter codePoint of integer type as an argument, which is to be tested. Return value: This method returns a boolean value. It returns True if the specified character is digit, else it returns False. Below programs illustrate the above method: Program 1:

Java

// This program demonstrates the use of
// isDigit(int codePoint) method of Character class.
import java.util.*;

public class GFG {
    public static void main(String[] args)
    {
        // create codePoints
        int cp1 = 57;
        int cp2 = 84;

        // Check whether the codePoints
        // are digit or not.
        System.out.println(
            "The codePoint cp1 is a digit -> "
            + Character.isDigit(cp1));
        System.out.println(
            "The codePoint cp2 is a digit -> "
            + Character.isDigit(cp2));
    }
}

Output:

The codePoint cp1 is a digit -> true
The codePoint cp2 is a digit -> false

Program 2:

Java

// This program demonstrates the use of
// isDigit(int codePoint) method of
// Character class.
import java.util.*;

public class Main {
    public static void main(String[] args)
    {
        // create codePoints
        int cp1 = 0x50;
        int cp2 = 0x06f8;

        // Check whether the codePoints
        // are digit or not.
        System.out.println(
            "The codePoint cp1 is a digit -> "
            + Character.isDigit(cp1));
        System.out.println(
            "The codePoint cp2 is a digit -> "
            + Character.isDigit(cp2));
    }
}

Output:

The codePoint cp1 is a digit -> false
The codePoint cp2 is a digit -> true

Reference: https://docs.oracle.com/javase/8/docs/api/java/lang/Character.html#isDigit-char-

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