V6008. Potential null dereference.

The analyzer detected a code fragment that may cause a null-dereference issue.

Consider the following examples, which trigger the V6008 diagnostic message:

if (obj != null || obj.isEmpty()) { ... }
if (obj == null && obj.isEmpty()) { ... }

All the conditions contain a logical mistake that results in null dereference. This mistake appears as the result of bad code refactoring or a typo.

The following are the fixed versions of the samples above:

if (obj == null || obj.isEmpty()) { .... }
if (obj != null && obj.isEmpty()) { .... }

These are very simple situations, of course. In real-life code, an object may be tested for null and used in different lines. If you see the V6008 warning, examine the code above the line that triggered it and try to find out why the reference is null.

Here's an example where an object is checked and used in different lines:

if (player == null) {
  ....
  String currentName = player.getName();
  ....
}

The analyzer will warn you about the issue in the line inside the 'if' block. There is either an incorrect condition or some other variable should have been used instead of 'player'.

Sometimes programmers forget that when testing two objects for null, one of them may appear null and the other non-null. It will result in evaluating the entire condition, and null dereference. For example:

if ((text == null && newText == null) && text.equals(newText)) {
  ....
}

This condition can be rewritten in the following way:

if ((text == null && newText == null) ||
    (text != null && newText != null && text.equals(newText))) {
  ....
}

This diagnostic is classified as: