Technology Fundamentals
July's Program Challenge
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For July's Challenge Program PhoneList, you created a program that maintains a phone list of your friends:
Show the differences when traversing the entries based upon insertion order, hash
code order, and sorted order by printing out the hash table keys and values.
A possible solution to the July 2002 Java Technology Fundamentals Program Challenge, PhoneList:
import java.util.*;
public class PhoneList {
public static void main(String args[]) {
// Create map - maintain insertion order
Map map = new LinkedHashMap();
// Add members
map.put("George", "202-456-1111");
map.put("Bill", "212-348-8882");
map.put("Hillary", "202-224-4451");
map.put("Elvis", "901-332-3322");
map.put("Jimmy", "229-924-6935");
// Print map
print(map, "Insertion Order:");
// Convert map to regular
map = new HashMap(map);
// Print map
print(map, "Hashing Order:");
// Convert map to sorted
map = new TreeMap(map);
// Print map
print(map, "Sorted");
}
private static void print(Map map, String message) {
System.out.println(message);
Set entries = map.entrySet();
Iterator iterator = entries.iterator();
while (iterator.hasNext()) {
Map.Entry entry = (Map.Entry)iterator.next();
System.out.println(entry.getKey() + " : "
+ entry.getValue());
}
System.out.println();
}
}
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Your result should look something like the following:
Insertion Order:
George : 202-456-1111
Bill : 212-348-8882
Hillary : 202-224-4451
Elvis : 901-332-3322
Jimmy : 229-924-6935
Hashing Order:
Hillary : 202-224-4451
George : 202-456-1111
Bill : 212-348-8882
Jimmy : 229-924-6935
Elvis : 901-332-3322
Sorted
Bill : 212-348-8882
Elvis : 901-332-3322
George : 202-456-1111
Hillary : 202-224-4451
Jimmy : 229-924-6935
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