Java Exercises: Convert a hexadecimal to a decimal number

Java Basic: Exercise-28 with Solution

Write a Java program to convert a hexadecimal to a decimal number.

Hexadecimal number: This is a positional numeral system with a radix, or base, of 16. Hexadecimal uses sixteen distinct symbols, most often the symbols 0-9 to represent values zero to nine, and A, B, C, D, E, F (or alternatively a, b, c, d, e, f) to represent values ten to fifteen.

Decimal number: The decimal numeral system is the standard system for denoting integer and non-integer numbers. It is also called base-ten positional numeral system.

Test Data:
Input any hexadecimal number: 25

Pictorial Presentation: Hexadecimal to Decimal number

Java: Convert a hexadecimal to a decimal number

Sample Solution:

Java Code:

import java.util.Scanner;

public class Exercise28 {
   public static int hex_to_decimal(String s)
             String digits = "0123456789ABCDEF";
             s = s.toUpperCase();
             int val = 0;
             for (int i = 0; i < s.length(); i++)
                 char c = s.charAt(i);
                 int d = digits.indexOf(c);
                 val = 16*val + d;
             return val;
    public static void main(String args[])
        String hexdec_num;
        int dec_num;
        Scanner scan = new Scanner(System.in);
        System.out.print("Input a hexadecimal number: ");
        hexdec_num = scan.nextLine();
        dec_num = hex_to_decimal(hexdec_num);
        System.out.print("Equivalent decimal number is: " + dec_num+"\n");

Sample Output:

Input a hexadecimal number: 25                                                                                 
Equivalent decimal number is: 37


Flowchart: Java exercises: Convert a hexadecimal to a decimal number

Java Code Editor:

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Previous: Write a Java program to convert a octal number to a hexadecimal number.
Next: Write a Java program to convert a hexadecimal to a binary number.

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Java: Tips of the Day


Counts the occurrences of a value in an array.

Use Arrays.stream().filter().count() to count total number of values that equals the specified value.

public static long countOccurrences(int[] numbers, int value) {
    return Arrays.stream(numbers)
            .filter(number -> number == value)

Ref: https://bit.ly/3kCAgLb