I am newbie in android. I want to resize a byte array in function. Is it possible or not. If any problem please suggest a solution to do it.
public void myfunction(){
byte[] bytes = new byte[1024];
....................
.... do some operations........
................................
byte[] bytes = new byte[2024];
}
To achieve the effect of resizing a byte array without loosing the content, there are several solutions in Java already mentioned:
1) ArrayList<Byte> (see the answers of a.ch. and kgiannakakis)
2) System.arraycopy() (see the answers of jimpic, kgiannakakis, and UVM)
Something like:
byte[] bytes = new byte[1024];
//
// Do some operations with array bytes
//
byte[] bytes2 = new byte[2024];
System.arraycopy(bytes,0,bytes2,0,bytes.length);
//
// Do some further operations with array bytes2 which contains
// the same first 1024 bytes as array bytes
3) I would like to add a third way which I think is most elegant: Arrays.copyOfRange()
byte[] bytes = new byte[1024];
//
// Do some operations with array bytes
//
bytes = Arrays.copyOfRange(bytes,0,2024);
//
// Do some further operations with array bytes whose first 1024 bytes
// didn't change and whose remaining bytes are padded with 0
Of course there are further solutions (e.g. copying the bytes in a loop). Concerning efficiency, see this
You can't resize an array in Java. You could use a List to do what you want:
List<Byte> bytes = new ArrayList<Byte>();
Another way will be to use System.arraycopy. In that case you will create a second array and copy the content of the first array into it.
You cannot do that. But you can create a new array and use System.arraycopy to copy the old contents to the new one.
You can do it like this:
bytes = new byte[2024];
But your old content will be discarded.If you need the old data as well, then need to create a new byte array with a diff size and call System.arrayCopy() method to copy data from old to new.
Use ArrayList<Byte> instead, Java arrays don't allow resizing, ArrayLists do, but make it a little bit different. You can't specify their size (actually you needn't - it is done automatically), you may specify initial capacity (which is good practice if you know how many elements will the ArrayList contain):
byte myByte = 0;
ArrayList<Byte> bytes = new ArrayList<Byte>(); //size is 0
ArrayList<Byte> bytes2 = new ArrayList<Byte>(1024); //initial capacity specified
bytes.add(myByte); //size is 1
...
I'd recommend you to look through this Java Collections tutorial.
