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

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 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
countOccurrences
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) .count(); }
Ref: https://bit.ly/3kCAgLb
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