Array type expected [compile-error]

Question

Im working with the following method:

public void m(List<? extends Object[]> objs){
    objs.stream()
        .map(oa -> oa[0])   //compile error
                            //array type expected
        .forEach(System.out::println); 

}

DEMO

Why doesn't it work? I thought everything that extends array can be viewed as an array. Actually I can get length from the array.

Answer 1

There is actually no such class that extends Object[] ; each array has a fixed type and its own class, eg MyClass[].class

You should use a typed method:

public <T> void m(List<T[]> objs){
    objs.stream()
            .map(oa -> oa[0])   // no compile error
            .forEach(System.out::println);

}