Question

In an interview my interviewer asked me :
What can go wrong if you replace && with & in the following code:

String a=null; if (a!=null && a.length()>10) {...}

Answer 1

&& is logical AND operator (executes short-circuit behavior, which means that the second operand is evaluated only if needed)

& is Bitwise AND operator (The bitwise & operator performs a bitwise AND operation).

Because no short-circuit behavior, you will get NullPointerException.