Converting BigDecimal to Integer

Question

I have Hibernate method which returns me a BigDecimal  I have another API method to which I need to pass that number but it accepts Integer as parameter  I cannot change return types or variable types of both methods    Now how to convert the BigDecimal into Integer and pass it to second method   Is there a way out of this

User · Answer

Can you guarantee that the BigDecimal will never contain a value larger than Integer MAX VALUE   If yes  then here s your code calling intValue   Integer valueOf bdValue intValue

User · Answer

See BigDecimal intValue

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Following should do the trick   BigDecimal d   new BigDecimal 10   int i   d intValue

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Well  you could call BigDecimal intValue        Converts this BigDecimal to an int  This conversion is analogous to a narrowing primitive conversion from double to short as defined in the Java Language Specification  any fractional part of this BigDecimal will be discarded  and if the resulting  BigInteger  is too big to fit in an int  only the low-order 32 bits are returned  Note that this conversion can lose information about the overall magnitude and precision of this BigDecimal value as well as return a result with the opposite sign    You can then either explicitly call Integer valueOf int  or let auto-boxing do it for you if you re using a sufficiently recent version of Java

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TL DR  Use one of these for universal conversion needs    Java 7 or below bigDecimal setScale 0  RoundingMode DOWN  intValueExact     Java 8     bigDecimal toBigInteger   intValueExact     Reasoning  The answer depends on what the requirements are and how you answer these question    Will the BigDecimal potentially have a non-zero fractional part  Will the BigDecimal potentially not fit into the Integer range  Would you like non-zero fractional parts rounded or truncated  How would you like non-zero fractional parts rounded    If you answered no to the first 2 questions  you could just use BigDecimal intValueExact   as others have suggested and let it blow up when something unexpected happens   If you are not absolutely 100  confident about question number 2  then intValue   is always the wrong answer   Making it better  Let s use the following assumptions based on the other answers    We are okay with losing precision and truncating the value because that s what intValueExact   and auto-boxing do We want an exception thrown when the BigDecimal is larger than the Integer range because anything else would be crazy unless you have a very specific need for the wrap around that happens when you drop the high-order bits    Given those params  intValueExact   throws an exception when we don t want it to if our fractional part is non-zero   On the other hand  intValue   doesn t throw an exception when it should if our BigDecimal is too large   To get the best of both worlds  round off the BigDecimal first  then convert   This also has the benefit of giving you more control over the rounding process   Spock Groovy Test  void  test BigDecimal rounding          given      BigDecimal decimal   new BigDecimal Integer MAX VALUE - 1 99      BigDecimal hugeDecimal   new BigDecimal Integer MAX VALUE   1 99      BigDecimal reallyHuge   new BigDecimal  10000000000000000000000000000000000000000000000       String decimalAsBigIntString   decimal toBigInteger   toString       String hugeDecimalAsBigIntString   hugeDecimal toBigInteger   toString       String reallyHugeAsBigIntString   reallyHuge toBigInteger   toString        expect   decimals that can be truncated within Integer range to do so without exception        GOOD  Truncates without exception          decimal intValue      decimalAsBigIntString       BAD  Throws ArithmeticException  Non-zero decimal digits  because we lose information        decimal intValueExact      decimalAsBigIntString       GOOD  Truncates without exception          decimal setScale 0  RoundingMode DOWN  intValueExact      decimalAsBigIntString      and   truncated decimal that cannot be truncated within Integer range throw conversionOverflow exception        BAD  hugeDecimal intValue   is -2147483648 instead of 2147483648            hugeDecimal intValue      hugeDecimalAsBigIntString       BAD  Throws ArithmeticException  Non-zero decimal digits  because we lose information            hugeDecimal intValueExact      hugeDecimalAsBigIntString       GOOD  Throws conversionOverflow ArithmeticException because to large            hugeDecimal setScale 0  RoundingMode DOWN  intValueExact      hugeDecimalAsBigIntString      and   truncated decimal that cannot be truncated within Integer range throw conversionOverflow exception        BAD  hugeDecimal intValue   is 0            reallyHuge intValue      reallyHugeAsBigIntString       GOOD  Throws conversionOverflow ArithmeticException because to large            reallyHuge intValueExact      reallyHugeAsBigIntString       GOOD  Throws conversionOverflow ArithmeticException because to large            reallyHuge setScale 0  RoundingMode DOWN  intValueExact      reallyHugeAsBigIntString      and   if using Java 8  BigInteger has intValueExact   just like BigDecimal        decimal toBigInteger   intValueExact      decimal setScale 0  RoundingMode DOWN  intValueExact

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I found that the above did not work for me  I was pulling a cell value from a JTable but could not cast to double or int etc  My solution   Object obj   getTable   getValueAt row  0     where row 0 would always be a number  Hope this helps anyone still scrolling

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You would call myBigDecimal intValueExact    or just intValue    and it will even throw an exception if you would lose information  That returns an int but autoboxing takes care of that

User · Answer

Have you tried calling BigInteger intValue

[java] Converting BigDecimal to Integer

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