Question

• Write a JAVA program called DBConvertor that has two methods. The first one converts ANY user input binary into its equivalent decimal number. The second method converts ANY user input decimal number into its equivalent binary.​
• binaryToDecimal, decimalToBinary are the names for those methods.​
• binaryToDecimal receives a binary number as a string and returns a decimal number as an integer. And vice versa for the decimalToBinary method.​

Answer 1

Implement the program as follows:

1. import Scanner class
2. create a class DBConverter
3. define the method binaryToDecimal()
4. initialize decimal to 0
5. initialize n=0, and i = length of binary -1
6. repeat until index i>= 0, iterate over each character from last to first
7. calculate the int value of each character
8. calculate its positional value and add to decimal value
9. increment n and decrement i
10. return decimal value
11. define the method decimalToBinary()
12. initialize binary to ""
13. repeat until decimal>0
14. Prepend the remainder when decimal is divided by 2 to binary
15. divide decimal by 2
16. return binary
17. define main() method
18. initialize Scanner
19. ask the user to enter a binary value and read input
20. convert binary to decimal using binaryToDecimal()
21. ask the user to enter a decimal and read input
22. convert decimal to binary using decimalToBinary()

Program: DBConverter.java

import java.util.Scanner;                                                                                           /* import Scanner class */
public class DBConverter{                                                                                               /* create a class DBConverter */
        public static int binaryToDecimal(String binary){                                       /* define the method binaryToDecimal() */
                int decimal = 0;                                                                                                /* initialize decimal to 0 */
                int n = 0, i = binary.length()-1;                                                               /* initialize n=0, and i = length of binary -1 */
                while(i>=0){                                                                                                         /* repeat until index i>= 0, iterate over each character from last to first */
                        int temp = Integer.parseInt(""+binary.charAt(i));                       /* calculate the int value of each character */
                        decimal += temp*Math.pow(2, n);                                                         /* calculate its positional value and add to decimal value */
                        n++;                                                                                                            /* increment n and decrement i */
                        i--;
                }  
                return decimal;                                                                                                 /* return decimal value */
        }
        public static String decimalToBinary(int decimal){                                      /* define the method decimalToBinary() */
                String binary = "";                                                                                     /* initialize binary to "" */
                while(decimal>0){                                                                                            /* repeat until decimal>0 */
                        binary = decimal%2 + binary;                                                            /* Prepend the remainder when decimal is divided by 2 to binary */
                        decimal = decimal/2;                                                                            /* divide decimal by 2 */
                }
                return binary;                                                                                                  /* return binary */
        }
        public static void main(String[] args){                                                         /* define main() method */
                Scanner scnr = new Scanner(System.in);                                                  /* initialize Scanner */
                System.out.print("Enter a binary number : ");                                   /* ask the user to enter a binary value and read input */
                String binary = scnr.nextLine();
                System.out.println("Decimal is " + binaryToDecimal(binary));    /* convert binary to decimal using binaryToDecimal() */
                System.out.print("Enter a decimal number : ");                                  /* ask the user to enter a decimal and read input */
                int decimal = scnr.nextInt();
                System.out.println("Binary is " + decimalToBinary(decimal));    /* convert decimal to binary using decimalToBinary() */
        }
}

Screenshot:

Output:

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