java.math.BigInteger cannot be cast to java.lang.Integer

Question

I'm getting the following exception.

Caused by:

java.lang.ClassCastException: java.math.BigInteger cannot be cast to java.lang.Integer

with the following code

List queryResult = query.list();  for (Iterator<Object[]> it = queryResult.iterator(); it.hasNext();) {     Object[] result = it.next();     Integer childId = (Integer) result[0];     Integer grandChildCount = (Integer) result[1];     CompanyNode childNode = childNodes.get(childId);     childNode.setHasChildren(grandChildCount != 0);     childNode.setIsLeaf(grandChildCount == 0); } 

at this line

Integer grandChildCount = (Integer) result[1]; 

Does anybody have any idea?

Answer 1

You can use:

Integer grandChildCount = ((BigInteger) result[1]).intValue(); 

Or perhaps cast to Number to cover both Integer and BigInteger values.

Answer 2

As we see from the javaDoc, BigInteger is not a subclass of Integer:

java.lang.Object                      java.lang.Object    java.lang.Number                       java.lang.Number       java.math.BigInteger                    java.lang.Integer 

And that's the reason why casting from BigInteger to Integer is impossible.

Casting of java primitives will do some conversion (like casting from double to int) while casting of types will never transform classes.