Java Hexadecimal转Binary用法及代码示例

// Java program to convert Hexadecimal to Binary
import java.util.HashMap;
class GFG {
    // declaring the method to convert
    // Hexadecimal to Binary
    String hexToBinary(String hex)
    {
        // variable to store the converted
        // Binary Sequence
        String binary = "";
        // converting the accepted Hexadecimal
        // string to upper case
        hex = hex.toUpperCase();
        // initializing the HashMap class
        HashMap<Character, String> hashMap
            = new HashMap<Character, String>();
        // storing the key value pairs
        hashMap.put('0', "0000");
        hashMap.put('1', "0001");
        hashMap.put('2', "0010");
        hashMap.put('3', "0011");
        hashMap.put('4', "0100");
        hashMap.put('5', "0101");
        hashMap.put('6', "0110");
        hashMap.put('7', "0111");
        hashMap.put('8', "1000");
        hashMap.put('9', "1001");
        hashMap.put('A', "1010");
        hashMap.put('B', "1011");
        hashMap.put('C', "1100");
        hashMap.put('D', "1101");
        hashMap.put('E', "1110");
        hashMap.put('F', "1111");
        int i;
        char ch;
        // loop to iterate through the length
        // of the Hexadecimal String
        for (i = 0; i < hex.length(); i++) {
            // extracting each character
            ch = hex.charAt(i);
            // checking if the character is
            // present in the keys
            if (hashMap.containsKey(ch))
                // adding to the Binary Sequence
                // the corresponding value of
                // the key
                binary += hashMap.get(ch);
            // returning Invalid Hexadecimal
            // String if the character is
            // not present in the keys
            else {
                binary = "Invalid Hexadecimal String";
                return binary;
            }
        }
        // returning the converted Binary
        return binary;
    }
    // Driver Code
    public static void main(String[] args)
    {
        // instantiating the class
        GFG ob = new GFG();
       
        String hex = "deafa";
       
        System.out.println(hex.toUpperCase());
       
        // printing and calling the
        // hexToBinary() function
        System.out.println(ob.hexToBinary(hex));
    }
}

// Java program to convert Hexadecimal to Binary
class GFG {
    // method to convert Decimal to Binary
    String decimalToBinary(int decimal)
    {
        // variable to store the converted
        // binary string
        String binaryString = "";
        // loop to generate the binary
        while (decimal != 0) {
            // concatenating the remainder
            // on dividing by 2 to the
            // binary string
            binaryString = (decimal % 2) + binaryString;
            // updating the decimal integer
            // by dividing by 2 in each iteration
            decimal /= 2;
        }
        // loop to ensure that each
        // Hexadecimal character is
        // represented by 4 bits
        while (binaryString.length() % 4 != 0) {
            // adding leading 0's if the
            // character is represented by less
            // than 4 bits
            binaryString = "0" + binaryString;
        }
        // returning the converted binary string
        return binaryString;
    }
    // method to convert Hexadecimal to Binary
    String hexToBinary(String hexadecimal)
    {
        // declaring the variables
        int i;
        char ch;
        String binary = "";
        int returnedBinary;
        // converting the accepted Hexadecimal
        // String to upper case
        hexadecimal = hexadecimal.toUpperCase();
        // loop to iterate through the length
        // of the Hexadecimal String
        for (i = 0; i < hexadecimal.length(); i++) {
            // extracting the characters
            ch = hexadecimal.charAt(i);
            // condition to check if
            // the character is not a valid Hexadecimal
            // character
            if (Character.isDigit(ch) == false
                && ((int)ch >= 65 && (int)ch <= 70)
                       == false) {
                // returning Invalid Hexadecimal
                // String for the invalid Hexadecimal
                // character
                binary = "Invalid Hexadecimal String";
                return binary;
            }
            // checking if the character is a valid
            // Hexadecimal alphabet
            else if ((int)ch >= 65 && (int)ch <= 70)
                // converting alphabet to
                // corresponding value such as 10
                // for A and so on using ASCII code
                returnedBinary = (int)ch - 55;
            else
                returnedBinary
                    = Integer.parseInt(String.valueOf(ch));
            // converting the decimal to binary
            // by calling the decimalToBinary() method
            binary += decimalToBinary(returnedBinary);
        }
        // returning the converted binary sequence
        return binary;
    }
    // Driver Code
    public static void main(String[] args)
    {
        // instantiating the class
        GFG ob = new GFG();
         
        String hex = "abcfde";
       
        System.out.println(hex);
       
        // printing and calling the
        // hexToBinary() function to display the
        // output
        System.out.println(ob.hexToBinary(hex));
    }
}