Concat two ByteBuffers in Java

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How can I concat two ByteBuffers to one ByteBuffer?

The following doesn't work:

    ByteBuffer bb = ByteBuffer.allocate(100);
    ByteBuffer bb2 = ByteBuffer.allocate(200);
    bb.allocate(200).put(bb2);
    System.out.println(bb.array().length);

The length of bb is still 100.

Something like

bb = ByteBuffer.allocate(300).put(bb).put(bb2);

should do the job: Create a buffer that is large enough to hold the contents of both buffers, and then use the relative put-methods to fill it with the first and the second buffer. (The put method returns the instance that the method was called on, by the way)

concatenate two byteBuffers to a single, concatenate two byteBuffers to a single · java concatenation bytebuffer. Hi I've 2 byteBuffers and I want to concatenate them together to a single byteBuffer. I found  That’s mean you can concatenate two or more byte array in Java easily. In order to do this, we will first create some byte arrays and then we will create another byte array which will be used to concatenate all the byte arrays created before. You can concatenate byte arrays in Java with two easy ways, Using the Class ByteBuffer.

We'll be copying all data. Remember that this is why string concatenation is expensive!

public static ByteBuffer concat(final ByteBuffer... buffers) {
    final ByteBuffer combined = ByteBuffer.allocate(Arrays.stream(buffers).mapToInt(Buffer::remaining).sum());
    Arrays.stream(buffers).forEach(b -> combined.put(b.duplicate()));
    return combined;
}

Java Guava, concat() method with Examples. The concat() method of Bytes Class in the Guava library is used to concatenate the values of many arrays into a single array. These byte arrays to be concatenated are specified as parameters to this method. returns the array {1, 2, 3, 4, 5, 6, 7}. Well organized and easy to understand Web building tutorials with lots of examples of how to use HTML, CSS, JavaScript, SQL, PHP, Python, Bootstrap, Java and XML. w3schools .com THE WORLD'S LARGEST WEB DEVELOPER SITE

you can use the method here

https://github.com/ata4/ioutils/blob/047e401d73c866317af2e12f7803b3ee43eec80a/src/main/java/info/ata4/io/buffer/ByteBufferUtils.java#L289

and for example:

  ByteBuffer concat() {
int length = 0;
for (ByteBuffer bb : buffers) {
  bb.rewind();
  length += bb.remaining();
}
ByteBuffer bbNew = ByteBuffer.allocateDirect((int) length);

// put all buffers from list
for (ByteBuffer bb : buffers) {
  bb.rewind();
  bbNew.put(bb);

}
bbNew.rewind();
return bbNew;
}

ByteBuffer (Java Platform SE 8 ), Changes to the byte buffer's content will be visible in the view buffer, and vice versa; the two buffers' position, limit, and mark values are independent. The  In this short article, you will learn about different ways to concatenate two arrays into one in Java.. Using A Loop. The simplest way to concatenate two arrays in Java is by using the for loop:

Probably because on line3 i.e. bb.allocate(200).put(bb2); ,

bb.allocate(200) is returning a new Byte buffer (See https://docs.oracle.com/javase/7/docs/api/java/nio/ByteBuffer.html#allocate(int) ). That is not actually changing bb itself. So its still the bytebuffer of capacity 100 from line1.

Concatenate multiple byte array in Java, In order to do this, we will first create some byte arrays and then we will create another byte array which will be used to concatenate all the byte arrays created before. You can concatenate byte arrays in Java with two easy ways, Using the Class ByteBuffer. or you can also use ByteArrayOutputStream. Creates a new byte buffer whose content is a shared subsequence of this buffer's content. The content of the new buffer will start at this buffer's current position. Changes to this buffer's content will be visible in the new buffer, and vice versa; the two buffers' position, limit, and mark values will be independent.

Try the following code:

//store both ByteBuffer object as an array
byte[] array1 = ByteBuffer.allocate(100).array();
byte[] array2 = ByteBuffer.allocate(200).array();

//create a ByteBuffer which is big enough
ByteBuffer bigenough = ByteBuffer.allocate(array1.length + array2.length);

//put the two arrays in one ByteBuffer
ByteBuffer after1 = bigenough.put(array1, 0, array1.length);
ByteBuffer result = after1.put(array2, array1.length, array2.length);

//print the length of the combined array.
System.out.println(result.array().length);

ByteBuffer, public class ByteBuffer; extends java.lang.Object void, concat(ByteBuffer buf) Returns a 2-byte unsigned little-endian integer, starting at the current position. In java, string concatenation forms a new string that is the combination of multiple strings. There are two ways to concat string in java: 1) String Concatenation by + (string concatenation) operator. Java string concatenation operator (+) is used to add strings.

ByteBuffer (root 5.5.9-SNAPSHOT API), java.lang.Object · java.io.OutputStream. com.itextpdf.text.pdf.ByteBuffer append​. public ByteBuffer append(double d). Appends a string representation of a  When you run the program, the output will be: In the above program, we've two integer arrays array1 and array2. In order to combine (concatenate) two arrays, we find its length stored in aLen and bLen respectively. Then, we create a new integer array result with length aLen + bLen.

ByteString, java.lang.Object. com.google.protobuf.ByteString. All Implemented Interfaces: ByteBuffer objects such that the concatenation of their contents is equal to the The first chunk is small, with subsequent chunks each being double the size,  Will a finally block execute after a return statement in a method in Java? Concatenate a string given number of times in C++ programming; Sum triangle from an array in C programming; Importance of XOR operator in Java? How to convert an OutputStream to a Writer in Java? How to convert a String to an InputStream object in Java?

ioutils/ByteBufferUtils.java at master · ata4/ioutils · GitHub, A collection of some frequently used I/O utility Java classes, mostly related with byte buffers. - ata4/ioutils. To concatenate two Strings using arithmetic addition operator, provide left and right operands to + operator. The return value is a concatenated string. In the following example, we have defined two strings. And use + operator to concatenate these two strings.

Comments
  • WARNING : position and limit will both be set to capacity which is probably not what you would expect or want if you are going to process the resulting ByteBuffer further. You will want to call .flip() to be able to process the entire contents of the returned ByteBuffer by adding .flip(); at the end.
  • Yes, flip() or position(0) (I personally find the latter more readable)
  • result has length of 200. I expected to be 300.
  • I improved upon the anser. But have you looked into just combining the arrays themselves? Is the ByteBuffer essential to use?