List data type(ADT)

Lists Elements : a 1,a 2,a 3,… a i-1,a i, a i+1,…a n Null List contains: 0 elements Types of Operations on list 1.Insertion 2.Deletion 3.Search 4.Print 5.Isempty

List  An ordered collection (also known as a sequence).  The user of this interface has precise control over where in the list each element is inserted.  The user can access elements by their integer index (position in the list), and search for elements in the list.

Contd..  List allows duplicate elements.  The List interface provides four methods for positional (indexed) access to list elements.  Lists (like Java arrays) are zero based.  Thus, iterating over the elements in a list is typically preferable to indexing through it if the caller does not know the implementation.  LIST interface is a member of the Java Collections Framework.

List interface  An interface is shown, but the implementation details are hidden.  This implementation could be using arrays or linked list.  The various classes that implements list  AbstractList, AbstractSequentialList, ArrayList, AttributeList, CopyOnWriteArrayList, LinkedList, RoleList, RoleUnresolvedList, Stack, Vector

Implementing list using arrays Simple implementation is Arrays Size =Max N j A

N j A Insert(x,j) { For(k=size-1,k>j;k--) { A[k+1]=A[k]; } A[j]=x; Size++; } Inserting

Search Two types of Search functions 1.Find the element and return position. 1.Eg find(x); return the element x postion in the list 2.Find the element of given position. 1.Eg. Find_k th (p) which return k th element

Algorithm for find(x) find (x){ if (a[I]==x) print(i) /* Print the position of the element found */ } N j A Searching

Delete(x) { Pos=findpos(x); For(k=pos,k<size;k++) A[k]=a[k+1]; Size--; } Deleting x N Pos A

 Whenever we insert an element we increase size, i.e. size++;  Whenever we Delete an element we decrease size by one. i.e. size--;  Size we are taking should not exceed Max_size

List(ADT) operations.  add(); Appends an element to the end of the list.  Add(int index,E element); inserts the element at the specified position in the list.  addAll(Collection c); Append all of the elements in the collection to the end of the list.  addAll(int index, collection c); Inserts all the elements in the collection in to the list starting from the specified index.  Clear(); Removes all the elements from the list.  Contains (Object o); Retuns true if the list contains specified element.  containsAll(collection c); Returns true if the list contains all of the elements in the collection.

Contd…  equals(object e); Compares specified object with list for equality.  get(index e); Returns the element at the specified index.  hashCode(); Returns the hashcode for the list.  indexOf(Object o); Returns the index of first occurrence of the element o, returns -1 if not present.  isEmpty(); Returns true if the list contains no elements.  Remove(int index); Removes the element at the specified index); removeAll(Collection c); Remove all the elements from the list that are contained in the collection. toArray(); Returns the array of elements of the list.

Array List(ADT)  Resizable-array implementation of the List interface.  Implements all optional list operations, and permits all elements, including null.  In addition to implementing the List interface, this class provides methods to manipulate the size of the array that is used internally to store the list.

Contd..  Each ArrayList instance has a capacity.  The capacity is the size of the array used to store the elements in the list.  It is always at least as large as the list size.  As elements are added to an ArrayList, its capacity grows automatically.