Boolean Object and boolean variable issue in JAVA

Question

I declare a Boolean variable. For example Boolean dataVal=null;
Now if I execute the following code segment:

if(dataVal)
    System.out.prin         


        

Answer 1

When you evaluate the boolean value of a Boolean object Java unbox the value (autoboxing feature, since 1.5). So the real code is: dataVal.booleanValue(). Then it throws NullPointerException. With any boxed value, unboxing a null object throws this exception.

Before 1.5 you had to unbox the value by hand: if (dataVal.booleanValue()) so it was more evident (more verbose too :)