Java Byte Array to String to Byte Array

Question

I m trying to understand a byte   to string  string representation of byte   to byte   conversion    I convert my byte   to a string to send  I then expect my web service  written in python  to echo the data straight back to the client   When I send the data from my Java application     Arrays toString data toByteArray      Bytes to send      B 405217f8   Send  This is the result of Arrays toString   which should be a string representation of my byte data  this data will be sent across the wire      -47  1  16  84  2  101  110  83  111  109  101  32  78  70  67  32  68  97  116  97    On the python side  the python server returns a string to the caller  which I can see is the same as the string I sent to the server   -47  1  16  84  2  101  110  83  111  109  101  32  78  70  67  32  68  97  116  97    The server should return this data to the client  where it can be verified    The response my client receives  as a string  looks like   -47  1  16  84  2  101  110  83  111  109  101  32  78  70  67  32  68  97  116  97    I can t seem to figure out how to get the received string back into a  byte    Whatever I seem to try I end up getting a byte array which looks as follows      91  45  52  55  44  32  49  44  32  49  54  44  32  56  52  44  32  50  44  32  49  48  49  44  32  49  49  48  44  32  56  51  44  32  49  49  49  44  32  49  48  57  44  32  49  48  49  44  32  51  50  44  32  55  56  44  32  55  48  44  32  54  55  44  32  51  50  44  32  54  56  44  32  57  55  44  32  49  49  54  44  32  57  55  93    or I can get a byte representation which is as follows   B 2a80d889   Both of these are different from my sent data    I m sure Im missing something truly simple       Any help

User · Answer

Its simple to convert byte array to string and string back to byte array in java. we need to know when to use 'new' in the right way. It can be done as follows:

byte array to string conversion:

byte[] bytes = initializeByteArray();
String str = new String(bytes);

String to byte array conversion:

String str = "Hello"
byte[] bytes = str.getBytes();

For more details, look at: http://evverythingatonce.blogspot.in/2014/01/tech-talkbyte-array-and-string.html

User · Answer

String coolString    cool string    byte   byteArray   coolString getBytes     String reconstitutedString   new String byteArray    System out println reconstitutedString     That outputs  cool string  to the console   It s pretty darn easy

User · Answer

The kind of output you are seeing from your byte array   B 405217f8  is also an output for a zero length byte array  ie new byte 0    It looks like this string is a reference to the array rather than a description of the contents of the array like we might expect from a regular collection s toString   method   As with other respondents  I would point you to the String constructors that accept a byte   parameter to construct a string from the contents of a byte array  You should be able to read raw bytes from a socket s InputStream if you want to obtain bytes from a TCP connection    If you have already read those bytes as a String  using an InputStreamReader   then  the string can be converted to bytes using the getBytes   function  Be sure to pass in your desired character set to both the String constructor and getBytes   functions  and this will only work if the byte data can be converted to characters by the InputStreamReader    If you want to deal with raw bytes you should really avoid using this stream reader layer

User · Answer

If you want to convert the string back into a byte array you will need to use String getBytes    or equivalent Python function  and this will allow you print out the original byte array

User · Answer

You can t just take the returned string and construct a string from it    it s not a byte   data type anymore  it s already a string  you need to parse it  For example    String response     -47  1  16  84  2  101  110  83  111  109  101  32  78  70  67  32  68  97  116  97            response from the Python script  String   byteValues   response substring 1  response length   - 1  split       byte   bytes   new byte byteValues length    for  int i 0  len bytes length  i lt len  i         bytes i    Byte parseByte byteValues i  trim             String str   new String bytes        EDIT     You get an hint of your problem in your question  where you say  Whatever I seem to try I end up getting a byte array which looks as follows     91  45        because 91 is the byte value for    so  91  45      is the byte array of the string   -45  1  16       string   The method Arrays toString   will return a String representation of the specified array  meaning that the returned value will not be a array anymore  For example    byte   b1   new byte    97  98  99    String s1   Arrays toString b1   String s2   new String b1    System out println s1             - gt    97  98  99   System out println s2             - gt   abc     As you can see  s1 holds the string representation of the array b1  while s2 holds the string representation of the bytes contained in b1   Now  in your problem  your server returns a string similar to s1  therefore to get the array representation back  you need the opposite constructor method  If s2 getBytes   is the opposite of new String b1   you need to find the opposite of Arrays toString b1   thus the code I pasted in the first snippet of this answer

User · Answer

JDK8   import java util Base64    To string   String str   Base64 getEncoder   encode new byte    -47  1  16            To byte array   byte   bytes   Base64 getDecoder   decode  JVBERi0xLjQKMyAwIG9iago8P

User · Answer

Can you not just send the bytes as bytes  or convert each byte to a character and send as a string  Doing it like you are will take up a minimum of 85 characters in the string  when you only have 11 bytes to send  You could create a string representation of the bytes  so it d be   B 405217f8   which can easily be converted to a bytes or bytearray object in Python  Failing that  you could represent them as a series of hexadecimal digits   5b42403430353231376638   taking up 22 characters  which could be easily decoded on the Python side using binascii unhexlify

User · Answer

Use the below code API to convert bytecode as string to Byte array    byte   byteArray   DatatypeConverter parseBase64Binary  JVBERi0xLjQKMyAwIG9iago8P

User · Answer

JAVA 8   import java util Base64   String dummy   dummy string   byte   byteArray   dummy getBytes     byte   salt   new byte    -47  1  16        String encoded   Base64 getEncoder   encodeToString salt

User · Answer

What Arrays toString   does is create a string representation of each individual byte in your byteArray   Please check the API documentation  Arrays API  To convert your response string back to the original byte array  you have to use split      or something and convert it into a collection and then convert each individual item in there to a byte to recreate your byte array

User · Answer

What I did   return to clients   byte   result       encrypted data       String str   Base64 encodeBase64String result    return str    receive from clients    byte   bytes   Base64 decodeBase64 str     your data will be transferred in this format   OpfyN9paAouZ2Pw gDgGsDWzjIphmaZbUyFx5oRIN1kkQ1tDbgoi84dRfklf1OZVdpAV7TonlTDHBOr93EXIEBoY1vuQnKXaG CJyIfrCWbEENJ0gOVBr9W3OlFcGsZW5Cf9uirSmx JLLxTrejZzbgq3lpToYc3vkyPy5Y oFWYljy 3OcC S458uZFOc FfDqWGtT9pTUdxLDOwQ6EMe0oJBlMXm8J2tGnRja4F aVHfQddha2nUMi6zlvAm8i9KnsWmQG  ok25EHDbrFBP2Ia 6Bx SGS4skk 0couKwcPVXtTq8qpNh aYK1mclg7TBKHfF DHppwd30VULpA

[java] Java Byte Array to String to Byte Array

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