java - How to check if a BigInteger is null -

i have code may assign null biginteger. need check if null or not.

i've tried following things, , not work:

1. == check reference, not value.

   biginteger x = biginteger.one;  if(x== null) {     system.out.println( x ); } 

output of above prints x. (somehow boolean condition satisfied, though x not null).

2. following gives nullpointerexception upon comparing

   biginteger x = biginteger.one; biginteger mynull = null;  if(x.compareto(mynull) == 0 ) {     system.out.println( x ); } 

3. another npe:

   biginteger x = biginteger.one;  if(x.compareto(null) == 0) {     system.out.println( x ); } 

how check if biginteger null properly?

there difference between null reference , object value 0. check null references, use:

biginteger value = getvalue(); if (value != null) {   // } 

to check value 0, use:

biginteger value = getvalue(); if (!biginteger.zero.equals(value)) {   // } 

to ensure object neither null reference nor has value 0, combine both:

biginteger value = getvalue(); if (value != null && !value.equals(biginteger.zero)) {   // } 

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2015-06-26: edited according @arpit's comment.