HashSet: No guarantees concerning the order of iteration
TreeSet: Orders its elements based on their values
+More
HashSet VS TreeSet
HashSet offers constant time performance for the basic operations (add, remove, contains and size). It does not guarantee that the order of elements will remain constant over time.
TreeSet guarantees log(n) time cost for the basic operations (add, remove and contains). It also guarantees that elements of set will be sorted. Finally, it offers a few handy methods to deal with the ordered set like first(), last().
LinkedList allows for constant-time insertions or removals, but only sequential access of elements. You can walk the list forwards or backwards, but finding a position in the list takes time proportional to the size of the list.
ArrayList allows fast random read access, so you can retrieve any element in constant time. But adding or removing from anywhere but the end requires shifting all the latter elements over, either to make an opening or fill the gap.
Hashtable is synchronized, whereas HashMap is not.
Hashtable does not allow null keys or values. HashMap allows one null key and any number of null values.
One of HashMap's subclasses is LinkedHashMap, so in the event that you'd want predictable iteration order (which is insertion order by default), you could easily swap out the HashMap for a LinkedHashMap.
Exercise 1
Create intersection and union for Lists.
The methods should support ArrayLists, LinkedLists etc. (Generics are coming).
Exercise 2
Create a PriorityQueue that can handle integers in an ascending order. The maximum capacity of the queue should be 50.
Exercise 3
Find the intersection of two given HashMaps that share the same keys and return it in a new Hashmap. The values should be the ones coming from the secnod HashMaps.
Exercise 4
Create a method that accepts Java source code as input and creates a "bracket" fingerprint. A bracket fingerprint includes all brackets in their order of appearance.
For instance, consider the following snippet:
for (T t : list1) {
if(list2.contains(t)) {
list.add(t);
}
}
The fingerprint is the following: {{}}.
Be careful, you should use the most appropriate data structure.
