Java: How to check for null pointers efficiently

Question

There are some patterns for checking whether a parameter to a method has been given a null value.

First, the classic one. It is common in self-made code

Answer 1

The first option is the easiest one and also is the most clear.

It's not common in Java, but in C and C++ where the = operator can be included in a expression in the if statement and therefore lead to errors, it's often recommended to switch places between the variable and the constant like this:

if (NULL == variable) {
   ...
}

instead of:

if (variable == NULL) {
   ...
}

preventing errors of the type:

if (variable = NULL) { // Assignment!
   ...
}

If you make the change, the compiler will find that kind of errors for you.