CODEWITHSUNDEEP
javascala
Yuval Herziger
Yuval Herziger

Reputation: 1155

How to convert a String-represented ByteBuffer into a byte array in Java

I'm new to Java and I'm no sure how to do the following:

A Scala application somewhere converts a String into bytes: 

ByteBuffer.wrap(str.getBytes)

I collect this byte array as a Java String, and I wish to do the inverse of what the Scala code above did, hence get the original String (object str above).

Getting the ByteBuffer as a String to begin with is the only option I have, as I'm reading it from an AWS Kinesis stream (or is it?). The Scala code shouldn't change either.

Example string:

String str = "AAAAAAAAAAGZ7dFR0XmV23BRuufU+eCekJe6TGGUBBu5WSLIse4ERy9............";

How can this be achieved in Java?

EDIT

Okay, so I'll try to elaborate a little more about the process:

  1. A 3rd party Scala application produces CSV rows which I need to consume

  2. Before storing those rows in an AWS Kinesis stream, the application does the following to each row:

    ByteBuffer.wrap(output.getBytes);

  3. I read the data from the stream as a string, and the string could look like the following one:

    String str = "AAAAAAAAAAGZ7dFR0XmV23BRuufU+eCekJe6TGGUBBu5WSLIse4ERy9............";

  4. I need to restore the contents of the string above into its original, readable, form;

I hope I've made it clearer now, sorry for puzzling you all to begin with.

Upvotes: 3

Views: 12089

Answers (5)

binshi
binshi

Reputation: 1328

For Kinesis data blobs: 

private CharsetDecoder decoder = Charset.forName("UTF-8").newDecoder();
decoder.decode(record.getData()).toString();

Upvotes: 0

Lincoln
Lincoln

Reputation: 181

Sorry,wrong answer. Again,ByteBuffer is a java class. SO they may work the same way You need java version..

From kafka ApiUtils:

def writeShortString(buffer:ByteBuffer,string:String){
   if(String == null){
       buffer.putShort(-1)
   }
   else{
     val encodedString = string.getBytes(“utf-8”)
     if(encodedString.length > Short.MaxValue){
         throw YourException(Your Message)
     else{
        buffer.putShort(encodedString.length.asInstanceOf[Short])
        buffer.put(encodedString)
   }
  }

}

Upvotes: 0

DevArea
DevArea

Reputation: 1

public static void main(String[] args){
    String decoded = new String(bytesData);
    String actualString;
    try{
       actualString = new String(bytesData,"UTF-8");
       System.out.printLn("String is" + actualString);
    }catch(UnsupportedEncodingException e){
       e.printstacktrace();
    }
}

Upvotes: 0

Virginia Woolf
Virginia Woolf

Reputation: 1268

I m not sure if I understand the question exactly but do you mean this?

String decoded = new String(bytes);

Upvotes: 1

aioobe
aioobe

Reputation: 420921

If you want to go from byte[] to String, try new String(yourBytes).

Both getBytes and the String(byte[]) uses the default character encoding.

From Amazon Kinesis Service API Reference:

The data blob to put into the record, which is Base64-encoded when the blob is serialized.

You need to base64 decode the string. Using Java 8 it would look like:

byte[] bytes = Base64.getDecoder().decode("AAAAAAAAAAGZ7dFR0XmV23BR........");
str = new String(bytes, "utf-8"));

Other options: Base64 Encoding in Java

Upvotes: 3

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