Name: gm110360 Date: 02/11/2004


A DESCRIPTION OF THE REQUEST :
BigDecimal and BigInteger are immutable, so an optimization of the toString method is possible. This is especially critical since internally this is used in methods like doubleValue().

The first time the toString() method is calculated, just remember the result and short-circuit the algoritm for following calls by returning the stored value.

Since the radix 10 toString is the most common, and is the one used internally by the doubleValue() method, just remembering this one would give a performance increase by 2 orders of magnitude in some common applications


JUSTIFICATION :
For some calculations like for currency, storing the values as doubles present a possible rounding problem. Using a BigDecimal solves this problem. However using BigDecimal really slows rendering down.

Displaying BigDecimals in a table shows the impact.

In a table, the toString() method will be called every time the cell in rendered. This will either call the toString() method directly, or if using a DecimalFormat, the toString() method will be called indirectly by the calls to the doubleValue() method. Returning just the cached string is 2 orders of magnitude faster. And, since BigInteger and BigDecimal are immutable, there is no reason to calculate this again.


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Immediate response on subsequent calls to toString()
ACTUAL -
toString() calculations are done every time the toString() method is called, the the penality for calculating this is incurred every time.

CUSTOMER SUBMITTED WORKAROUND :
Subclass
(Incident Review ID: 238336)
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