A NullPointerException is thrown in case of an attempt to dereference a null value. The dereference may be a function call, a read or write of a field, or an array access. An NPE.COND error is reported for a local variable being dereferenced if it was checked for null earlier, and the check confirmed that its value might be null.

Example 1

15     static void printPoint(Point p) {
16         if (p == null) {
17             System.err.println("p is null");
18         }
19         if (p.x < 0 || p.y < 0) {
20             System.out.println("Invalid point");
21             return;
22         }
23         System.out.println(p);
24     }

NPE.COND is reported for line 19 since 'p' is dereferenced there, and 'p' could be null due to the check on line 16.

Related checkers

Extension

This checker can be extended through the Klocwork knowledge base. See Tuning Java analysis for more information.