Java to convert Hexidecimal to Signed 8-Bit Code

Question

I need to convert Hexideciamal numbers represented as a String to a Signed 8-Bit String.

For Example: Given this Code Snippet:

String hexideciaml = new String("50  4b e0  e7");
String signed8Bit = convertHexToSigned8Bit(hexideciaml);
System.out.print(signed8Bit);

The Output should be: "80 75 -32 -25"

So I pretty much want to implement part of this website in Java. https://www.mathsisfun.com/binary-decimal-hexadecimal-converter.html

Update: Solution needs to be for JRE6 with no other Jars.

Why would the "50" remain unhexified? I'd expect the output to be "80 75 -32 -25" — Roshan
– Roshan, Commented Jul 14, 2016 at 19:09
Parse the String using space as a delimiter. Then convert each value to an Integer with a radix of 16 via Integer.parseInt(String, int). Cast that value to byte to convert it to a signed value. — Vince
– Vince, Commented Jul 14, 2016 at 19:29
You are correct @Reimeus. Updating question. Sorry about that. — javaPlease42
– javaPlease42, Commented Jul 14, 2016 at 19:40

Vladislav Gutov · Accepted Answer · 2016-07-14 20:05:53Z

3

Java 1.8 (stream)

import java.util.Arrays;

public class HexToDec {

    public static String convertHexToSigned8Bit(String hex) {
        return Arrays
                .stream(hex.split(" +"))
                .map(s -> "" + (byte) Integer.parseInt(s, 16))
                .reduce((s, s2) -> s + " " + s2)
                .get();
    }


    public static void main(String[] args) {
        String hexidecimal = "50  4b e0  e7";
        String signed8Bit = convertHexToSigned8Bit(hexidecimal);
        System.out.print(signed8Bit);
    }

}

Java <1.8

import java.util.Arrays;

public class HexToDec {

    public static String convertHexToSigned8Bit(String hex) {
        String[] tokens = hex.split(" +");
        StringBuilder result = new StringBuilder();
        for (int i = 0; i < tokens.length - 1; i++) { //append all except last
            result.append((byte) Integer.parseInt(tokens[i], 16)).append(" ");
        }
        if (tokens.length > 1) //if more than 1 item in array, add last one
            result.append((byte) Integer.parseInt(tokens[tokens.length - 1], 16));
        return result.toString();
    }


    public static void main(String[] args) {
        String hexidecimal = "50  4b e0  e7";
        String signed8Bit = convertHexToSigned8Bit(hexidecimal);
        System.out.print(signed8Bit);
    }

}

Output is: 80 75 -32 -25

edited Jul 14, 2016 at 20:05

answered Jul 14, 2016 at 19:40

Vladislav Gutov

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3 Comments

javaPlease42 Over a year ago

Hmm does not seem to compile. I get this error The method stream(String[]) is undefined for the type Arrays, solution needs to be for JRE6. Also where is s2 initialized?

Vladislav Gutov Over a year ago

Ofc it won't compile for JRE6. I used streams, which are present since JRE8. Wait a sec, I will rewrite it for JRE6

javaPlease42 Over a year ago

Works perfectly with JRE 6. I suggest you update your answer with both solutions, 1 for Jre6 and 1 for Jre8. Then I will except your answer. Thank you!

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