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Java program to convert hexadecimal byte to decimal

Given a byte value in the hexadecimal format, we have to convert hexadecimal byte to decimal.
Submitted by Nidhi, on March 02, 2022

Problem Solution:

In this program, we will convert the hexadecimal byte into a decimal number and print the result.

Program/Source Code:

The source code to convert hexadecimal byte to decimal is given below. The given program is compiled and executed successfully.

// Java program to convert hexadecimal Byte 
// to an integer

public class Main {
  static int getNum(char ch) {
    int num = 0;

    if (ch >= '0' && ch <= '9') {
      num = ch - 0x30;
    } else {
      switch (ch) {
      case 'A':
      case 'a':
        num = 10;
        break;

      case 'B':
      case 'b':
        num = 11;
        break;

      case 'C':
      case 'c':
        num = 12;
        break;

      case 'D':
      case 'd':
        num = 13;
        break;

      case 'E':
      case 'e':
        num = 14;
        break;

      case 'F':
      case 'f':
        num = 15;
        break;

      default:
        num = 0;
      }
    }
    return num;
  }

  static int hex2int(String hex) {
    int x = 0;

    x = (getNum(hex.charAt(0))) * 16 + (getNum(hex.charAt(1)));

    return x;
  }

  public static void main(String[] args) {
    String hexValue = "7F";
    int intValue = 0;

    intValue = hex2int(hexValue);

    System.out.printf("Value is: %d\n", intValue);
  }
}

Output:

Value is: 127

Explanation:

In the above program, we imported the "java.util.Scanner" package to read input from the user. And, created a public class Main. It contains three static methods getNum(), hex2int(), and main().

The getNum() method is used to get a decimal digit from a hexadecimal digit and return the result to the calling method.

The hex2int() method is used to return a decimal number from the hexadecimal number and return the result to the calling method.

The main() method is an entry point for the program. Here, we created a string variable hexValue initialized with "7F". Then we converted the hex value into decimal using the hex2int() method and printed the result.

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