Java Array of Bytes

I开发者_如何学JAVAf I create an array of bytes with byte[], what would be the size of each element? Can they be resized/merged?

Thanks,

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Not sure what you meant by resized and merged

from the documentation:

byte: The byte data type is an 8-bit signed two's complement integer. It has a minimum value of -128 and a maximum value of 127 (inclusive). The byte data type can be useful for saving memory in large arrays, where the memory savings actually matters. They can also be used in place of int where their limits help to clarify your code; the fact that a variable's range is limited can serve as a form of documentation.

Edit: If by resized/merged you are talking about the array itself, there's nothing special about a byte array compared to other arrays.

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There are two ways to allocate an array.

A) allocate an empty array of a given size:

byte[] ba1 = new byte[18]; // 18 elements

B) allocate an array by specifying the contents

byte[] ba2 = {1,2,3,4,5}; // 5 elements

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The size would be a byte per element.

They can not be re-sized. However you can merge them yourself using System.arrayCopy() by creating a new array and copying your source arrays into the new array.

Edit 1:

There is also an 8-byte overhead for the object header and a 4-byte overhead for the array length, for a total overhead of 12 bytes. So small arrays are relatively expensive.

Check out GNU Trove and Fastutil. They are libraries that make working with primitive collections easier.

Edit 2:

I read in one of your response that you're doing object serialization. You might be interested in ByteBuffers. Those make it easy to write out various primitive types to a wrapped array and get the resulting array. Also check out Google protocol buffers if you want easily serialized structured data types.