How to use BigInteger

Question

I have this piece of code  which is not working   BigInteger sum   BigInteger valueOf 0   for int i   2  i  lt  5000  i          if  isPrim i             sum add BigInteger valueOf i              The sum variable is always 0  What am I doing wrong

User · Answer

BigInteger is an immutable class  So whenever you do any arithmetic  you have to reassign the output to a variable

User · Answer

Yes it s Immutable      sum add BigInteger valueOf i      so the method add   of BigInteger class does not add new BigIntger value to its own value  but creates and returns a new BigInteger reference without changing the current BigInteger and this is what done even in the case of Strings

User · Answer

Biginteger is an immutable class   You need to explicitly assign value of your output to sum like this   sum   sum add BigInteger valueof i

User · Answer

BigInteger is immutable   The javadocs states that add     r eturns a BigInteger whose value is  this   val    Therefore  you can t change sum  you need to reassign the result of the add method to sum variable   sum   sum add BigInteger valueOf i

User · Answer

Actually you can use   BigInteger sum  new BigInteger  12345      for creating object for BigInteger class But the problem here is you cannot give a variable in the double quotes So we have to use the valueOf   method and we have to store the answer in that sum again So we will write   sum  sum add BigInteger valueOf i

User · Answer

sum   sum add BigInteger valueOf i     The BigInteger class is immutable  hence you can t change its state  So calling  add  creates a new BigInteger  rather than modifying the current

User · Answer

Since you are summing up some int values together  there is no need to use BigInteger  long is enough for that  int is 32 bits  while long is 64 bits  that can contain the sum of all int values

User · Answer

java math BigInteger is an immutable class so we can not assign new object in the location of already assigned object  But you can create new object to assign new value like   sum   sum add BigInteger valueOf i

User · Answer

Other replies have nailed it  BigInteger is immutable   Here s the minor change to make that code work   BigInteger sum   BigInteger valueOf 0   for int i   2  i  lt  5000  i          if  isPrim i             sum   sum add BigInteger valueOf i

[java] How to use BigInteger?

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