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

This error occurs when you try to cast a BigDecimal object to an Integer object. Since BigDecimal and Integer are two different classes in Java, it is not possible to cast one to the other.

To solve this error, you need to use the appropriate methods to convert the BigDecimal to an Integer.

For example, you can use the intValue() method of BigDecimal to convert it to an Integer, like this:

BigDecimal bd = new BigDecimal("10.5");
int i = bd.intValue();

Alternatively, you can create a new Integer object using the value of the BigDecimal, like this:

BigDecimal bd = new BigDecimal("10.5");
Integer i = Integer.valueOf(bd.intValue());

Note that if the value of the BigDecimal is larger than the maximum value of an Integer, an ArithmeticException will be thrown.