arrays - How to convert Java String into byte[]?

Question

Is there any way to convert Java String to a byte[] (not the boxed Byte[])?

In trying this:

System.out.println(response.split("

")[1]);
System.out.println("******");
System.out.println(response.split("

")[1].getBytes().toString());

and I'm getting separate outputs. Unable to display 1st output as it is a gzip string.

<A Gzip String>
******
[B@38ee9f13

The second is an address. Is there anything I'm doing wrong? I need the result in a byte[] to feed it to gzip decompressor, which is as follows.

String decompressGZIP(byte[] gzip) throws IOException {
    java.util.zip.Inflater inf = new java.util.zip.Inflater();
    java.io.ByteArrayInputStream bytein = new java.io.ByteArrayInputStream(gzip);
    java.util.zip.GZIPInputStream gzin = new java.util.zip.GZIPInputStream(bytein);
    java.io.ByteArrayOutputStream byteout = new java.io.ByteArrayOutputStream();
    int res = 0;
    byte buf[] = new byte[1024];
    while (res >= 0) {
        res = gzin.read(buf, 0, buf.length);
        if (res > 0) {
            byteout.write(buf, 0, res);
        }
    }
    byte uncompressed[] = byteout.toByteArray();
    return (uncompressed.toString());
}

Answer 1

The object your method decompressGZIP() needs is a byte[].

So the basic, technical answer to the question you have asked is:

byte[] b = string.getBytes();
byte[] b = string.getBytes(Charset.forName("UTF-8"));
byte[] b = string.getBytes(StandardCharsets.UTF_8); // Java 7+ only

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However the problem you appear to be wrestling with is that this doesn't display very well. Calling toString() will just give you the default Object.toString() which is the class name + memory address. In your result [B@38ee9f13, the [B means byte[] and 38ee9f13 is the memory address, separated by an @.

For display purposes you can use:

Arrays.toString(bytes);

But this will just display as a sequence of comma-separated integers, which may or may not be what you want.

To get a readable String back from a byte[], use:

String string = new String(byte[] bytes, Charset charset);

---

The reason the Charset version is favoured, is that all String objects in Java are stored internally as UTF-16. When converting to a byte[] you will get a different breakdown of bytes for the given glyphs of that String, depending upon the chosen charset.