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This compliant solution uses the safeAdd() and safeMultiply() methods defined in the "Precondition Testing" section to perform secure integral operations or throw ArithmeticException on overflow.:
| Code Block | ||
|---|---|---|
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public static int multAccum(int oldAcc, int newVal, int scale)
throws ArithmeticException {
return safeAdd(oldAcc, safeMultiply(newVal, scale));
}
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This compliant solution uses the BigInteger technique to detect overflow.:
| Code Block | ||
|---|---|---|
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private static final BigInteger bigMaxInt =
BigInteger.valueOf(Integer.MAX_VALUE);
private static final BigInteger bigMinInt =
BigInteger.valueOf(Integer.MIN_VALUE);
public static BigInteger intRangeCheck(BigInteger val)
throws ArithmeticException {
if (val.compareTo(bigMaxInt) == 1 ||
val.compareTo(bigMinInt) == -1) {
throw new ArithmeticException("Integer overflow");
}
return val;
}
public static int multAccum(int oldAcc, int newVal, int scale)
throws ArithmeticException {
BigInteger product =
BigInteger.valueOf(newVal).multiply(BigInteger.valueOf(scale));
BigInteger res =
intRangeCheck(BigInteger.valueOf(oldAcc).add(product));
return res.intValue(); // Safe conversion
}
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