Java Collections Framework – II

Java Collections Framework – II
Bruce Eckel, Thinking in Java, 4th edition, PrenticeHall,
New Jersey, cf. http://mindview.net/Books/TIJ4
Gilad Bracha, “Generics in the Java Programming
Language” a.k.a “The Generics Tutorial”, Julho de 2004
cf. http://java.sun.com/j2se/1.5/pdf/generics-tutorial.pdf
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José Valente de Oliveira
20-1
JCF interface hierarchy
1
Interface List and its implementations
Interface Queue
2
Queue
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http://w3.ualg.pt/~jvo/ensino.php
20-5
Queue – implementing with an Array
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http://w3.ualg.pt/~jvo/ensino.php
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3
Queue – implementing with an Array
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http://w3.ualg.pt/~jvo/ensino.php
20-7
Interface Map
4
Interface Map
interface Map<K, V> {
void clear(); // optional
boolean containsKey(Object key);
boolean containsValue(Object value);
Set<Map.Entry<K,V>> entrySet();
boolean equals(Object o);
V get(Object key);
int hashCode();
boolean isEmpty();
Set<K> keySet() ;
V put(K key, V value);
void putAll(Map<? extends K,? extends V> m);
V remove(Object key) ;
int size();
Collection<V> values(); }
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José Valente de Oliveira
20-9
Interface SortedMap
interface SortedMap<K, V> extends Map<K, V> {
Comparator<? super K> comparator();
Set<Map.Entry<K,V>> entrySet();
K firstKey();
SortedMap<K,V> headMap(K toKey);
Set<K> keySet();
K lastKey();
SortedMap<K,V> subMap(K fromKey, K toKey);
SortedMap<K,V> tailMap(K fromKey);
Collection<V> values();
}
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José Valente de Oliveira
20-10
5
How to sellect a collection?
Com
Com
chave?
chave
Admite
duplicados
?
N
N
Set
Collection
{abstract}
Chave
inteira?
Com
chave?
S
List
S
N
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Map
20-11
José Valente de Oliveira
How to sellect a collection?
Com
Com
chave?
chave
Admite
duplicados
?
S
Bag
N
N
Set
Collection
{abstract}
Chave
inteira?
Com
chave?
S
List
S
N
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José Valente de Oliveira
Map
20-12
6
Implementations
Underlying data strucuture
Interfaces
Hash table
Set
Resizable array
HashSet
List
Tree
Linked list
TreeSet
ArrayList
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LinkedHashSet
LinkedList
Queue
Map
Hash table + Linked list
LinkedList
HashMap
TreeMap
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LinkedHashMap
20-13
Example 8: 2 of 5 code reader
„
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To generate the bar code
each bit equals to 1 is
converted into a wide-bar,
while each bit equals to 0 is
converted into a narrow bar,
a space being inserted
between bars.
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20-14
7
Example 8: 2 of 5 code reader
Now, suppose that each wide bar is represented by 3 consecutive ones
(111) and that each narrow bar is represented by a single one (1), the
space being represented by a 0. With this bar representation, the
decimal character 1, which is coded by the 5-bits 10001, has the bar
representation 1110101010111.
Write a program that reads a sequence of 0s and 1s in the 2 of 5
barcode format and decode it, i.e., answer the represented decimal
characters.
Input
A string of 0s and 1s in the 2 of 5 code format with a size not exceeding
200.
Output
The decoded decimal characters
Sample input
111010101011101110111010101
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José Valente de Oliveira
Sample output
13
20-15
Example 8: 2 of 5 code reader
Sample input
111 1 1 1 111
1 0 0 0 1
Sample output
1
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111 111 1 1 1
1
1 0 0 0
3
José Valente de Oliveira
20-16
8
class CodeReader {
private static Map<String, String> codes =
new HashMap<String,String>();
static {
codes.put("00110", "0");
codes.put("10001", "1");
codes.put("01001", "2");
codes.put("11000", "3");
codes.put("00101", "4");
codes.put("10100", "5");
codes.put("01100", "6");
codes.put("00011", "7");
codes.put("10010", "8");
codes.put("01010", "9");
}
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José Valente de Oliveira
20-17
public String decimal(String s) {
String[] nospaces = s.split("0");
String result = "";
String code = "";
for(int i = 0; i < nospaces.length; i++) {
if (nospaces[i].compareTo("1")==0) code+="0";
else if (nospaces[i].compareTo("111")==0) code+="1";
if ((i+1)%5 ==0) {
result+=codes.get(code);
code="";
}
}
return result;
}
} // end of class
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José Valente de Oliveira
20-18
9
public class Main {
public static void main(String[] args) {
Scanner sc = new Scanner (System.in);
CodeReader cr = new CodeReader();
System.out.println(cr.decimal(sc.next()));
}
}
¾java Main <ret>
111010101011101110111010101
13
¾
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José Valente de Oliveira
20-19
Punch list summary
„
Core interfaces and implementations (continued)
‰
‰
‰
„
List
Queue
Map
Map, application example
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José Valente de Oliveira
20-20
10