Why can't a “Class” variable be passed to instanceof?

Question

Why doesn\'t this code compile?

    public boolean isOf(Class clazz, Object obj){
        if(obj instanceof clazz){
            return true;
        }else{
          


        

Answer 1

Firstly, instanceof requires that the operand on the right is an actual class (e.g. obj instanceof Object or obj instanceof Integer) and not a variable of type Class. Secondly, you have made a fairly common newbie mistake that you really should not do... the following pattern:

if ( conditional_expression ){
    return true;
} else{
    return false;
}

The above can be refactored into:

return conditional_expression;

You should always perform that refactoring, as it eliminates a redundant if...else statement. Similarly, the expression return conditional_expression ? true : false; is refactorable to the same result.