How to convert ASCII to hexadecimal values in java

Question

How to convert ASCII to hexadecimal values in java.

For example:

ASCII: 31 32 2E 30 31 33

Hex: 12.013

Answer 1

You did not convert ASCII to hexadecimal value. You had char values in hexadecimal, and you wanted to convert it to a String is how I'm interpreting your question.

    String s = new String(new char[] {
        0x31, 0x32, 0x2E, 0x30, 0x31, 0x33
    });
    System.out.println(s); // prints "12.013"

If perhaps you're given the string, and you want to print its char as hex, then this is how to do it:

    for (char ch : "12.013".toCharArray()) {
        System.out.print(Integer.toHexString(ch) + " ");
    } // prints "31 32 2e 30 31 33 "

You can also use the %H format string:

    for (char ch : "12.013".toCharArray()) {
        System.out.format("%H ", ch);
    } // prints "31 32 2E 30 31 33 "

Answer 2

It's not entirely clear what you are asking, since your "hex" string is actually in decimal. I believe you are trying to take an ASCII string representing a double and to get its value in the form of a double, in which case using Double.parseDouble should be sufficient for your needs. If you need to output a hex string of the double value, then you can use Double.toHexString. Note you need to catch NumberFormatException, whenever you invoke one of the primitive wrapper class's parse functions.

byte[] ascii = {(byte)0x31, (byte)0x32, (byte)0x2E, (byte)0x30, (byte)0x31, (byte)0x33};
String decimalstr = new String(ascii,"US-ASCII");
double val = Double.parseDouble(decimalstr);
String hexstr = Double.toHexString(val);