Java - Collection - ArrayList

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ArrayList:
  • It extends AbstractList
  • It implements List, RandomAccess, Cloanable, Serializable
  • Resizable-array implementation of the List interface.
  • Duplicate Allowed
  • Insertion Ordered Maintained
  • Constant time for this methods ->  size, isEmpty, get, set
  • O(n) time for this method -> add
  • Capactiy - Capacity is the size of the array used to store elements in the list
  • Using ensureCapacity application can increase the capacity of an ArrayList Instance
  • If inital capacity is not provided then default capacity is 10.
  • int newcapacity = oldcapacity + (oldcpacity >> 1 ) ; For Example : oldcapacity =10 ; then newcapacity = 15
  • When elements are removed, gap will be created. Then need to shift subsequenct element in the left using below,
    System.arraycopy( elementData, index+1, elementData, index, numMoved )

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