Why is this wrong? About Java 8 streaming media

public interface Filter<M> {

public interface Filter<M> {

    boolean match(M m);

    public static <T> Collection<T> filter(Collection<T> collection,Filter<T> filter) {
        return collection.stream().filter(filter::match).collect(Collectors.toList());
    }

    ////////////////////////////////////////////////////////////////

    public static void main(String[] args) {
        ArrayList<Integer> intList = new ArrayList<>(Arrays.asList(1,2,3,4,5,6,7,8));
        System.out.println(intList);

        List<Integer> list = filter(intList,null);

        System.out.println(list);
    }
}

I'm learning the Java 8 streaming function. This is the code I have a problem with

I don't know why the parameter intlist doesn't match the filter () method Java should know < T > this is an integer, right?

Solution

I'm not sure why you encountered this particular error, but the problem is that your method declares that it will return collection < T >, but you try to assign the result to list < T > If you change the declaration of the filter to:

public static <T> List<T> filter(Collection<T> collection,Filter<T> filter)

... then it compiles without problem