Array vs arraylist vs hashmap vs treeset in java

Unordered : Both does not guarantee ordered elements. Null Values : Both can store null values and uses index to refer to their elements.Д¤. Duplicate elements : Both array and arraylist can contain duplicate elements.ДЈ. add and get method : Performance of Array and ArrayList are similar for the add and get operations. Import import public class ArrayArrayListExample ДЎ. One get a misconception that we can store primitives(int,float,double) in ArrayList, but it is not true Primitives : ArrayList can not contains primitive data types (like int, float, double) it can only contains Object while Array can contain both primitive data types as well as objects. ДЄdd() or get() operation : adding an element or retrieving an element from the array or arraylist object has almost same performance, as for ArrayList object these operations run in constant time.ДЈ. Resize() opertation : Automatic resize of ArrayList will slow down the performance as it will use temporary array to copy elements from the old array to new array.ДЄrrayList is internally backed by Array during resizing as it calls the native implemented method System.arraењњopy(src,srcPos,dest,destPos,length). Performance : Performance of Array and ArrayList depends on the operation you are performing : As elements are added to an ArrayList its capacity grows automatically.Дў. Each ArrayList object has instance variable capacity which indicates the size of the ArrayList. Resizable : Array is static in size that is fixed length data structure, One can not change the length after creating the Array object.ДЄrrayList is dynamic in size.

Read Also : Difference between HashSet and TreeSetДifference between Array and ArrayList in Java with ExampleДЎ. Difference between array and arraylist in java include eight points namely Resizable, Performance, Traversal ,Primitives, Length, Type-Safety, Adding elements, Multi-dimensional. This question checks whether candidate know about static and dynamic nature of array.We have already discussed other popular java interview questions like difference between comparable and comparator and difference between arraylist and vector.

Difference between array and arraylist in java is considered as a starting interview question.

Array vs arraylist vs hashmap vs treeset in java