VM Size

The calculation for the size of a single instance of the VM is as follows:

• long and double fields = 8 bytes.

• All other field types = 4 bytes.

• Instance size = size of all non-static fields (including inherited fields) 8-byte header. No alignment or other implicit costs.

• An array has a 12-byte header plus storage for all its elements (rounded up to a multiple of 4 bytes). The size of a single element is:

  byte[], boolean[] = 1 byte

  short[], char[] = 2 bytes

  long[], double[] = 8 bytes

  All other arrays = 4 bytes

  arrays are also not aligned beyond the 4 bytes that the rounding ensures.