Re: Java Memory question
On 03/14/2011 10:10 AM, Eric wrote:
If I create a native object like
byte[] myData = new byte[byteSize];
then I fill it with data,
how do I release the memory?
Do I just null it?
myData = null;
All objects [1] in Java are garbage collected, so the memory will be
freed when the last reference to an object is lost. You can of course
have references to an object as variables within the scope, elements of
an Object array, or as objects in a class [2]. If it's a local variable,
the reference will be lost when leaving the scope within which it is
defined (i.e., pair of curly braces); you can lose the reference earlier
by explicitly nullifying it.
To move it to a new object using as little memory as possible do I
just null each?
byte[] myNewData = new byte[byteSize];
for (int byteLoop = 0; byteLoop< byteSize; byteLoop ++) {
myNewData[byteLoop] = myData[byteLoop];
myData[byteLoop] = null;
}
Or is there a better way to move it without eating double memory?
Judging by the code you're trying to write, byte[] myNewData = myData;
would probably be more than sufficient, since that gives the new data a
reference to the same memory to begin with, and it doesn't involve
copying the array again. If you need a subarray of only a portion of the
data, java.util.Arrays.copyOf might work better for you.
[1] Well, primitives aren't, but they aren't exactly objects to begin with.
[2] Or they can be rooted by the JVM while being used by native APIs,
but I digress.
--
Beware of bugs in the above code; I have only proved it correct, not
tried it. -- Donald E. Knuth