Convert a byte array to integer in Java and vice versa

java types endianness
Chris picture Chris · Oct 1, 2011 · Viewed 299.3k times · Source

I want to store some data into byte arrays in Java. Basically just numbers which can take up to 2 Bytes per number.

I'd like to know how I can convert an integer into a 2 byte long byte array and vice versa. I found a lot of solutions googling but most of them don't explain what happens in the code. There's a lot of shifting stuff I don't really understand so I would appreciate a basic explanation.

Answer

Jeff Mercado picture Jeff Mercado · Oct 1, 2011

Use the classes found in the java.nio namespace, in particular, the ByteBuffer. It can do all the work for you.

byte[] arr = { 0x00, 0x01 };
ByteBuffer wrapped = ByteBuffer.wrap(arr); // big-endian by default
short num = wrapped.getShort(); // 1

ByteBuffer dbuf = ByteBuffer.allocate(2);
dbuf.putShort(num);
byte[] bytes = dbuf.array(); // { 0, 1 }

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