Java NullPointerException: Cannot invoke "java.lang.Long.longValue()" because "lineId" is null

The NullPointerException is occurring in the LineController class at line 26. It is caused by trying to invoke the longValue() method on a null value for the lineId variable. The code is trying to convert the lineId from a Long object to a primitive long value, but since lineId is null, the NullPointerException is thrown.\n\nTo fix this issue, you need to ensure that the lineId variable is not null before invoking the longValue() method. You can add a null check before invoking the method, like this:\n\njava\nif (lineId != null) {\n long id = lineId.longValue();\n // Rest of the code\n}\n\n\nThis will prevent the NullPointerException from occurring when lineId is null.