Chapter 17 The Map ADT

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Chapter 17 The Map ADT

• Presented by
• Wade Apel

2
Contents

• What are maps
• How are they implemented
• Compare JDS vs Java Implementations
• Benefits
• References

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MAP

• Definition To plan or delineate, especially in
  detail arrange
• Synonyms- search table, dictionary, associative
  array, associative container
• Example of uses Dictionary, Address Book,
  Lists, etc.

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How is works

• There are 2 main parts to a map
• Key
• Value

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Interface (JDS)

• Public interface Map extends Collection
• public boolean containsKey (Object key)
• public Object get(Object key)
• public void removeKey (Object key)
• public void set (Object key, Object value)

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Javas Map Interface

• Clear( )
• containsKey(ObjectKey)
• containsValue(Object value)
• entrySet( )
• equals(Object o)
• get(Object key)
• hashCode( )

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Javas Map Interface (Continued)

• isEmpty( )
• keySet( )
• put(Object key, Object value)
• putAll(Map t)
• remove(Object key)
• size( )
• values( )

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Example
9
Timing Tests
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Map Adapter

• private class Association implements Comparable,
  Serializable
• public Object key
• public Object value
• Association (Object k, Object v) key k
  value v
• public int hashCode () return key.hashCode()
  
• public boolean equals (Object test)
• if (test instanceof Association)
• Association pair (Association) test
• return key.equals(pair.key)
• return key.equals(test)
• public int compareTo (Object testElement)
• Association pair (Association) testElement
• return test.compare(key, pair.key)

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Uses

• Mapjava.awt
• java.awt.datatransfer 
• java.awt.font 
• java.awt.im 
• java.security 
• java.sql 
• java.text 
• java.util 
• java.util.jar 
• javax.swing 

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Benifits

• Easy of use
• By extending the number of associations,
  searching large lists are fast

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References

• Sun Microsystems Java Documentation
• http//java.sun.com/j2se/1.3/docs/api/java/util/M
  ap.html
• Classic Data Structures in Java
• by Timothy Budd