How to get biggest BigDecimal value

Looking at the source BigDecimal stores it as a BigInteger with a radix,

private BigInteger intVal;
private int scale;

and from BigInteger

/** All integers are stored in 2's-complement form.
63:    * If words == null, the ival is the value of this BigInteger.
64:    * Otherwise, the first ival elements of words make the value
65:    * of this BigInteger, stored in little-endian order, 2's-complement form. */
66:   private transient int ival;
67:   private transient int[] words;

So the Largest BigDecimal would be,

ival = Integer.MAX_VALUE;
words = new int[Integer.MAX_VALUE]; 
scale = 0;

You can figure out how to set that. :P

[Edit] So just to calculate that, In binary that's,

(2^35)-2 1's (I think?)

in 2's complement

01111111111111111...until your RAM fills up.

Its an arbitrary precision class, it will get as large as you'd like until your computer runs out of memory.