为什么在此Java程序中出现ArrayIndexOutOfBoundsException？

Question

In Java, I am doing some work with RandomAccessFile. I have a file that is 8192 bytes, or 8kb.

The following is causing an ArrayIndexOutOfBoundsException:

File file = new File("TestFile1");
raf = new RandomAccessFile(file, "rw");
byte[] temp = new byte[4096];
raf.read(temp, 4096, 4096);

Even something like this causes the same error:

raf.read(temp, 4096, 1);

Though something like this works perfectly:

raf.read(temp, 0, 4096);

When I run the following, I get 8192, which is why I am confused as to why this is not working:

System.out.println(raf.getChannel().size());

Why am I getting an out of bounds error if I try to read from the second half of the file?

Answer 1

Instead of:

raf.getBytes(temp,4096,4096);

it sounds like you want:

raf.seek(4096); raf.getBytes(temp,0,4096);

The second parameter of getBytes gives the offset into the buffer into which the content will be read, not the offset into the file.