Check if there is enough memory to allocate a byte array

Question

I need to load a file into memory. Before I do this, I want to make sure that there is enough memory left on my virtual machine. If not, I would like to show an error message. I want to avoid an exception OutOfMemory.

an approach:

• Get file size of my file
• Use Runtime.getRuntime().freeMemory()
• Check if it fits

Will this work or do you have other suggestions?

Answer 1

The problem with any “check first and then do” strategy is that there may be changes between “check” and “do” that make the whole thing useless.

", " , , . "check first", , .

. - , , , .

, , . Java , -, , (, ).

---

, , , , , . 400M, 600, , 400M.

, (, 600 1M), , 400. , 400 .

, , , , , . , . , .

, , , (, 100M 10% - ), . . - , , .

Answer 2

, - .

Answer 3

FileChannel.map(FileChannel.MapMode, long, long). (, POSIX mmap) . (, ) .