What problem are you trying to solve?

Code conciseness.

x instanceof SomeType is guaranteed to give false when x is null.
Thus there's no need to check x != null additionally.

Describe the situation before applying the recipe

        if (x != null && x instanceof String) {
            System.out.println("String value: " + x);
        }

Describe the situation after applying the recipe

        if (x instanceof String) {
            System.out.println("String value: " + x);
        }