Use
table.put(key, val);
to add a new key/value pair or overwrite an existing key's value.
From the Javadocs:
V put(K key, V value): Associates the specified value with the specified key in this map (optional operation). If the map previously contained a mapping for the key, the old value is replaced by the specified value. (A map m is said to contain a mapping for a key k if and only if m.containsKey(k) would return true.)