How to implement isEmpty() for hashmap using stream?

oded ivry :

I'm implementing my own hashmap, using stream as much as possible. I can't figure out the right syntax for isEmpty().

I've tried many forms of:

 return buckets.entrySet().stream().forEach(List::isEmpty());

Here is part of the code:

public class HashMap<K, V> implements Map<K, V> {

    private static final int DEFAULT_CAPACITY = 64;
    private List<List<Entry<K, V>>> buckets;
    private int modCount = 0;
    private KeySet keySet;
    private EntrySet entrySet;
    private ValuesCollection valColl;

    //CTOR
    public HashMap() {
         buckets = new ArrayList<>(DEFAULT_CAPACITY);

         for (int i = 0; i < DEFAULT_CAPACITY; ++i) {
            buckets.add(i, new LinkedList<Entry<K, V>>());
         }
    }
}

I'd like to write a simple stream like:

return buckets.stream().mapToInt(List::size).sum();

for isEmpty().

Samuel Philipp :

You can use this:

public boolean isEmpty() {
    return buckets.stream().allMatch(List::isEmpty);
}

This returns true if buckets is empty or all sublists are empty.