For instance, you could interpret the Set method contains that returns true or false depending on if an object is a memeber as a lookup method.
Well! Set interface do have such a method
contains(). Isn't it??
from API
doc
public boolean contains(Object o)
Returns true if this set contains the specified element. More formally, returns true if and only if this set contains an element e such that (o==null ? e==null : o.equals(e)).