1. Difference between Array list and Vector in Java? - Both use same data structure to store the elements that is array. - Array list is not synchronized; multiple threads can use the array list. So it has best performance. -Vector is synchronized; one thread can access the vector at a time. - Vector will grow double its size. - Array list grow half of its size. 2. Differences between Hash Map and Hash table? - Hash map store the elements in form of key and value pair. - Hash table store the elements in form of key and value pair. - Hash map and Hash table does not maintain any insertion order. - Hash map allow single null key and multiple null value. - Hash table does not allow single null key and value. - Hash Map is not synchronized but hash table is synchronized 3. What is linked hash map? - Linked hash map is same as Hash map instead it maintain insertion order. 4. What is difference between Hash Map and Tree Map? - Hash map allow sing