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.

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