UnnecessaryNullCheckBeforeInstanceOf.md

Pattern: Unnecessary null check before instanceof

Issue: -

Description

There is no need to check for null before an instanceof; the instanceof keyword returns false when given a null argument.

Example:

if (x != null && x instanceof SomeClass) {
    // should drop the "x != null" check
}

if (x instanceof SomeClass && x != null) {
    // should drop the "x != null" check
}

// should drop the "x != null" check
(x != null && x instanceof SomeClass) ? foo : bar

if (x != null && x instanceof SomeClass && x.isValid()) {
    // this is OK and causes no violation because the x.isValid() requires a non null reference
}

Further Reading

• CodeNarc - UnnecessaryNullCheckBeforeInstanceOf