JAVA COLLECTIONS FRAMEWORK CHEAT SHEET CODE

(The same element cannot be in the set more than once.) TreeMap: Will sort the keys in natural order.LinkedMap: Behind this there is a doubly linked list.Setting the value of an existing element is not a structural modification.

Structural modification means addition or deletion of element(s) from the list.

JAVA COLLECTIONS FRAMEWORK CHEAT SHEET CODE

If multiple threads access an ArrayList concurrently then we must externally synchronize the block of code which modifies the list either structurally or simply modifies an element. A Vector defaults to doubling the size of its array, while the ArrayList increases its array size by 50 percent. When an element is inserted into an ArrayList or a Vector, the object will need to expand its internal array if it runs out of room. Internally, both the ArrayList and Vector hold onto their contents using an Array. handling of growth of the stored data is different.Vector is synchronized, ArrayList is not.Vector: it is very similar to ArrayList.But adding an item anywhere is fast, because the links need to be changed, but shifting is not needed. To get an item at a particular index can be slower, because the list needs to iterate until that item. In LinkedList, each element stores a reference to the previous and to the next element. If you add items near the end of the list, ArrayList can be more efficient than LinkedList. If you want to add or remove items anywhere in the list, also in the middle, use LinkedList. LinkedList: this is based on doubly linked list data structure.Near to the end it is faster, because less elements need to be shifted. Adding item at the beginning takes long time because the items need to be shifted. Accessing elements by index is very fast. If you only want to add or remove items in the end of your list, use ArrayList. But adding or removing entries from the beginning is slow - internally this means copying all the remaining entries to a new array. Meaning that removing entries from the end is fast - internally only the length of the array is shortened. LinkedList (this one implements the Queue and Deque interface as well)īasic rules of thumb for ArrayList and LinkedList:.This is a small cheat sheet and rules of thumb for using Java Collections Framework.Īll the Java Collections Framework classes implement the Collection interface.

Java collections framework cheat sheet