public void addValues(final Set<String> values) { if (values != null || !values.isEmpty()) { //compiler warning here on values.isEmpty(). Null pointer access: The variable values can only be null at this location } } Why am I seeing this NullPointerAccess warning, though I am guarding against the null in the first check. If the value is null first check would fail and it will return without even going to the second check.
Can I ignore this warning.
I am using Eclipse for development.
If values is null, values != null will be evaluated to false and then !values.isEmpty() will be evaluated, leading to a NPE.
You probably meant
if (values != null && !values.isEmpty())
Can I ignore this warning.
Don't ignore warnings, they are there for something.
Why am I seeing this NullPointerAccess warning, though I am guarding against the null in the first check.
No you're not. If values is null, the first condition is false; therefore the second condition is evaluated, this is how the logical or operator works.
You probably meant to use && instead.
You may think you're guarding against null, but you're not. If values is null, then values!=null will be false (so the next condition will need to be evaluated) and then !values.isEmpty() will raise a NullPointerException.
What you seem to mean is:
if (values!=null && !values.isEmpty()) { ... If values is null, the code will still try to evaluate values.isEmpty(). Use the && operation instead:
if(values != null && !values.isEmpty()){ // blah... } 
