Convert Java string to byte array

Question

I have a byte array which I\'m encrypting then converting to a string so it can be transmitted. When I receive the string I then have to convert the string back into a byte

Answer 1

You can't just use getBytes() on two different machines, since getBytes uses the plattform's default charset.

Decode and encode the array with a specified charset (i.e. UTF-8) to make sure you get the correct results.

Answer 2

This looks like Base64. Take a look at commons-codec Base64 class.

Answer 3

First do convertion of your byte array to proper string, by doing

String line= new String(Arrays.toString(your_array))

Then send it and use function below

public static byte[] StringToByteArray(String line)
{

    String some=line.substring(1, line.length()-1);     
    int element_counter=1;

    for(int i=0; i<some.length(); i++)
    {           
        if (some.substring(i, i+1).equals(","))
        {
            element_counter++;
        }       

    }
    int [] comas =new int[element_counter-1];
    byte [] a=new byte[element_counter];
    if (a.length==1)
    {
        a[0]= Byte.parseByte(some.substring(0));
    }       
    else 
    {
        int j=0;
        for (int i = 0; i < some.length(); i++) 
        {
            if (some.substring(i, i+1).equals(","))
            {
                comas[j]=i;
                j++;
            }
        }           
        for (int i=0; i<element_counter; i++)
        {
            if(i==0)
            {
                a[i]=Byte.parseByte(some.substring(0, comas[i]));
            }
            else if (i==element_counter-1)
            {
                a[i]=Byte.parseByte(some.substring(comas[comas.length-1]+2));
            }
            else
            {
                a[i]=Byte.parseByte(some.substring(comas[i-1]+2, comas[i]));
            }

        }
    }
    return a;

}

Answer 4

You used array.toString(), which is implemented like this:

return "[B@" + Integer.toString(this.hashCode(), 16);

(In fact it inherits the definition from Object, and the part before the @ simply is the result of getClass().getName().)

And the hashCode here does not depend on the content.

Instead, use new String(array, encoding).

Of course, this only works for byte-arrays which are really representable as Java strings (which then contain readable characters), not for arbitrary arrays. There better use base64 like Bozho recommended (but make sure to use it on both sides of the channel).