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CS2005 Week 7 Lectures Set Abstract Data Type
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Aims Describe the Set Abstract Data Type
CS2005 Aims Describe the Set Abstract Data Type Illustrate different implementations of the Set ADT Describe the Java Iterator concept
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Learning Outcomes specify the Set ADT
CS2005 Learning Outcomes specify the Set ADT write a Java program using one of the java.util set classes use an iterator recall the main points of Watt & Brown chapter 9.
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CS2005 The Set ADT A set is a collection of elements, without any imposed order
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Set Concepts Null set (empty set) Universal set Disjoint sets Subset
CS2005 Set Concepts Null set (empty set) Universal set Disjoint sets Subset Equality
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Set ADT Essential Operations create: Set add: Element Set Set
CS2005 Set ADT Essential Operations create: Set add: Element Set Set contains: Element Set Boolean remove: Element Set Set isEmpty: Set Boolean
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Set ADT (ii) Other Operations size: Set Integer
CS2005 Set ADT (ii) Other Operations size: Set Integer equals: Set Set Boolean copy: Set Set areDisjoint: Set Set Boolean isSubset: Set Set Boolean union: Set Set Set intersection : Set Set Set difference : Set Set Set
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Set Implementations Bitmap e.g. to represent the set { ‘C’, ‘X’ }
CS2005 Set Implementations Bitmap e.g. to represent the set { ‘C’, ‘X’ } see java.util.BitSet class
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Set Implementations (ii)
CS2005 Set Implementations (ii) Array e.g. to represent the set { “baker”, “butcher”, “grocer” }
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Set Implementations (iii)
CS2005 Set Implementations (iii) Linked List Binary Search Tree Hash Table
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Sets in Java Collection Classes
CS2005 Sets in Java Collection Classes HashSet TreeSet addAll, retainAll, removeAll operations
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Iterators need for following concept for sets
CS2005 Iterators need for following concept for sets 1. for every member, m, of the set s 1.1 process m Iterator used to solve this problem public interface Iterator { public abstract boolean hasNext(); public abstract Object next(); public abstract void remove(); }
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Using an Iterator java.util.Iterator i;
CS2005 Using an Iterator java.util.Iterator i; for (i = s.iterator(); i.hasNext(); ) { Object obj = i.next(); // the following code processes obj … }
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CS2005 Sample code ArraySet TestArraySet HTML file
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