ISO-8859-1 encoding and binary data preservation

character-encoding, iso-8859-1, java

Solution

`"\u00F6"` is not a byte array. It's a string containing a single char. Execute the following test instead:

public static void main(String[] args) throws Exception {
    byte[] b = new byte[] {(byte) 0x00, (byte) 0xf6};
    String s = new String(b, "ISO-8859-1"); // decoding
    byte[] b2 = s.getBytes("ISO-8859-1"); // encoding
    System.out.println("Are the bytes equal : " + Arrays.equals(b, b2)); // true
}

To check that this is true for any byte, just improve the code an loop through all the bytes:

public static void main(String[] args) throws Exception {
    byte[] b = new byte[256];
    for (int i = 0; i < b.length; i++) {
        b[i] = (byte) i;
    }
    String s = new String(b, "ISO-8859-1");
    byte[] b2 = s.getBytes("ISO-8859-1");
    System.out.println("Are the bytes equal : " + Arrays.equals(b, b2));
}

ISO-8859-1 is a standard encoding. So the language used (Java, C# or whatever) doesn't matter.

Here's a Wikipedia reference that claims that every byte is covered:

In 1992, the IANA registered the character map ISO_8859-1:1987, more commonly known by its preferred MIME name of ISO-8859-1 (note the extra hyphen over ISO 8859-1), a superset of ISO 8859-1, for use on the Internet. This map assigns the C0 and C1 control characters to the unassigned code values thus provides for 256 characters via every possible 8-bit value.

(emphasis mine)

Problem

I read in a comment to an answer by @Esailija to a question of mine that ISO-8859-1 is the only encoding to fully retain the original binary data, with exact byte<->codepoint matches I also read in this answer by @AaronDigulla that : In Java, ISO-8859-1 (a.k.a ISO-Latin1) is a 1:1 mapping I need some insight on this. This will fail (as illustrated here) : ``` // \u00F6 is ö System.out.println(Arrays.toString("\u00F6".getBytes("utf-8"))); // prints [-61, -74] System.out.println(Arrays.toString("\u00F6".getBytes("ISO-8859-1"))); // prints [-10] ``` Questions - I admit I do not quite get it - why does it not get the bytes in the code above ? - Most importantly, where is this (byte preserving behavior of `ISO-8859-1`) specified - links to source, or JSL would be nice. Is it the only encoding with this property ? - Is it related to `ISO-8859-1` being the default default ? See also this question for nice counter examples from other charsets.

Original source

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