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How to convert Java String into byte[]?

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

In trying this:

System.out.println(response.split("\r\n\r\n")[1]);
System.out.println("******");
System.out.println(response.split("\r\n\r\n")[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());
}
Sorry, I'm trying to convert a String to bytearray and back and getting a wrong result. I'll edit it in a while and get back.
Your problem is that String.getBytes() does indeed return a byte array, but your belief that the toString() of a byte array will return a useful result is incorrect.

S
Stewart

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

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.


string.getBytes("UTF-8") requires handling an UnsupportedEncodingException, while string.getBytes(Charset.forName("UTF-8")) does not. Arguing as to which method is "better" I leave as an exercise for the reader.
string.getBytes(StandardCharsets.UTF_8) can also be used, and it is the same as string.getBytes(Charset.forName("UTF-8"))
I believe StandardCharsets is new with Java 7
I don't understand why this answer got so many upvotes. It may be right, but it's not very helpful ... just a couple of lines of code, most of which the OP already had, and not explaining what difference Charset.forName("UTF-8") makes or why it's important.
@LarsH You make a good point. To be honest, I never expected this answer to become so popular. I have now expanded the answer in order to "deserve" the upvotes. Hopefully it's an improvement.
P
Prabhakaran Ramaswamy
  String example = "Convert Java String";
  byte[] bytes = example.getBytes();

Beware: getBytes() is platform dependent. Better choice is to use getBytes(StandardCharsets.UTF_8)
e
eebbesen

Simply:

String abc="abcdefghight";

byte[] b = abc.getBytes();

What if abc contains non US-ASCII characters, like "greater than 2³² − 1" or just binary data (like "�A���b2")?
this does not work for characters like this string has only 5 characters. However when I use getBytes() i got 7 characters.
A
Ankur Shanbhag

Try using String.getBytes(). It returns a byte[] representing string data. Example:

String data = "sample data";
byte[] byteData = data.getBytes();

V
Vimal Bera

You can use String.getBytes() which returns the byte[] array.


L
Lucas Hoepner

You might wanna try return new String(byteout.toByteArray(Charset.forName("UTF-8")))


Thanks for showing other way around from bytes to String.
Y
Yardack

It is not necessary to change java as a String parameter. You have to change the c code to receive a String without a pointer and in its code:

Bool DmgrGetVersion (String szVersion);

Char NewszVersion [200];
Strcpy (NewszVersion, szVersion.t_str ());
.t_str () applies to builder c ++ 2010

F
Favnir Liorenth

I know I'm a little late tothe party but thisworks pretty neat (our professor gave it to us)

public static byte[] asBytes (String s) {                   
           String tmp;
           byte[] b = new byte[s.length() / 2];
           int i;
           for (i = 0; i < s.length() / 2; i++) {
             tmp = s.substring(i * 2, i * 2 + 2);
             b[i] = (byte)(Integer.parseInt(tmp, 16) & 0xff);
           }
           return b;                                            //return bytes
    }

This decodes hex-encoded byte array. Something very different from what this question is about.