How to Convert a String to Bytearray

How to convert Java String into byte[]?

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);

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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.

How to convert a String to Bytearray

In C# running this

UnicodeEncoding encoding = new UnicodeEncoding();
byte[] bytes = encoding.GetBytes("Hello");

Will create an array with

72,0,101,0,108,0,108,0,111,0

For a character which the code is greater than 255 it will look like this

If you want a very similar behavior in JavaScript you can do this (v2 is a bit more robust solution, while the original version will only work for 0x00 ~ 0xff)

var str = "Hello竜";var bytes = []; // char codesvar bytesv2 = []; // char codes
for (var i = 0; i < str.length; ++i) {  var code = str.charCodeAt(i);    bytes = bytes.concat([code]);    bytesv2 = bytesv2.concat([code & 0xff, code / 256 >>> 0]);}
// 72, 101, 108, 108, 111, 31452console.log('bytes', bytes.join(', '));
// 72, 0, 101, 0, 108, 0, 108, 0, 111, 0, 220, 122console.log('bytesv2', bytesv2.join(', '));

How to convert string to byte array in Python

encode function can help you here, encode returns an encoded version of the string

In [44]: str = "ABCD"

In [45]: [elem.encode("hex") for elem in str]
Out[45]: ['41', '42', '43', '44']

or you can use array module

In [49]: import array

In [50]: print array.array('B', "ABCD")
array('B', [65, 66, 67, 68])

Java: Converting byte string to byte array

When converting byte[] to String, you should use this,

new String(b, "UTF-8");

instead of,

b.toString();

When you are converting byte array to String, you should always specify a character encoding and use the same encoding while converting back to byte array from String. Best is to use UTF-8 encoding as that is quite powerful and compact encoding and can represent over a million characters. If you don't specify a character encoding, then platform's default encoding may be used which may not be able to represent all characters properly when converted from byte array to String.

Your method when dealt appropriately, should be written something like this,

    public static void main(String args[]) throws Exception {
        byte[] b = myFunction();
//      String bstring = b.toString(); // don't do this
        String bstring = new String(b, "UTF-8");
        byte[] ser = bstring.getBytes("UTF-8");
        /* Here the methode to convert the bstring to byte[], and call it ser */
        String deser = new String(ser, "UTF-8");
    }

How to Convert String to Byte Array?

You can try like this:

string str= "some string";
var bytes = System.Text.Encoding.UTF8.GetBytes(str);

And to decode:

var decodeString = System.Text.Encoding.UTF8.GetString(bytes);

Best way to convert string to bytes in Python 3?

If you look at the docs for bytes, it points you to bytearray:

bytearray([source[, encoding[, errors]]])

Return a new array of bytes. The bytearray type is a mutable sequence of integers in the range 0 <= x < 256. It has most of the usual methods of mutable sequences, described in Mutable Sequence Types, as well as most methods that the bytes type has, see Bytes and Byte Array Methods.

The optional source parameter can be used to initialize the array in a few different ways:

If it is a string, you must also give the encoding (and optionally, errors) parameters; bytearray() then converts the string to bytes using str.encode().

If it is an integer, the array will have that size and will be initialized with null bytes.

If it is an object conforming to the buffer interface, a read-only buffer of the object will be used to initialize the bytes array.

If it is an iterable, it must be an iterable of integers in the range 0 <= x < 256, which are used as the initial contents of the array.

Without an argument, an array of size 0 is created.

So bytes can do much more than just encode a string. It's Pythonic that it would allow you to call the constructor with any type of source parameter that makes sense.

For encoding a string, I think that some_string.encode(encoding) is more Pythonic than using the constructor, because it is the most self documenting -- "take this string and encode it with this encoding" is clearer than bytes(some_string, encoding) -- there is no explicit verb when you use the constructor.

I checked the Python source. If you pass a unicode string to bytes using CPython, it calls PyUnicode_AsEncodedString, which is the implementation of encode; so you're just skipping a level of indirection if you call encode yourself.

Also, see Serdalis' comment -- unicode_string.encode(encoding) is also more Pythonic because its inverse is byte_string.decode(encoding) and symmetry is nice.

How to convert byte array to string and vice versa?

Your byte array must have some encoding. The encoding cannot be ASCII if you've got negative values. Once you figure that out, you can convert a set of bytes to a String using:

byte[] bytes = {...}
String str = new String(bytes, StandardCharsets.UTF_8); // for UTF-8 encoding

There are a bunch of encodings you can use, look at the supported encodings in the Oracle javadocs.

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