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9) Stockage des objets |
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| Texte original |
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Traducteur :
Jérome Quelin |
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Both versions of fill( ) take
an argument that determines the number of items to add to the container. In
addition, there are two generators for the map: RandStringPairGenerator,
which creates any number of pairs of gibberish Strings with length
determined by the constructor argument; and StringPairGenerator, which
produces pairs of Strings given a two-dimensional array of String.
The StringGenerator also takes a two-dimensional array of String
but generates single items rather than Pairs. The static
rsp, geography, countries, and capitals objects provide
prebuilt generators, the last three using all the countries of the world
and their capitals. Note that if you try to create more pairs than are
available, the generators will loop around to the beginning, and if you are
putting the pairs into a Map, the duplicates will just be
ignored.
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Les deux versions de fill() acceptent un argument qui
détermine le nombre d'éléments à ajouter dans le conteneur. De plus, il existe deux générateurs
pour le tableau associatif : RandStringPairGenerator, qui génére un nombre de
paires de Strings aléatoires dont la taille est déterminée par l'argument du
constructeur ; et StringPairGenerator, qui produit des paires de
Strings à partir d'un tableau bidimensionnel de Strings.
StringGenerator accepte lui aussi un tableau bidimensionnel de
Strings mais génére des éléments individuels plutôt que des
Pairs. Les objets static rsp, geography,
countries et capitals fournissent des générateurs intégrés, les
trois derniers utilisant les pays du monde et leur capitale. Notez que si on essaie de créer plus
de paires que le nombre disponible dans le tableau, les générateurs retourneront au début du
tableau, et dans le cas d'une Map, les doublons seront simplement
ignorés.
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Here is the predefined dataset, which
consists of country names and their capitals. It is set in a small font to
prevent taking up unnecessary space:
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Voici l'ensemble de données prédéfinies, qui consiste en noms de pays avec
leur capitale. Il est affiché avec une petite fonte afin de réduire l'espace
occupé :
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//: com:bruceeckel:util:CountryCapitals.java
package com.bruceeckel.util;
public class CountryCapitals {
public static final String[][] pairs = {
// Africa
{"ALGERIA","Algiers"}, {"ANGOLA","Luanda"},
{"BENIN","Porto-Novo"}, {"BOTSWANA","Gaberone"},
{"BURKINA FASO","Ouagadougou"}, {"BURUNDI","Bujumbura"},
{"CAMEROON","Yaounde"}, {"CAPE VERDE","Praia"},
{"CENTRAL AFRICAN REPUBLIC","Bangui"},
{"CHAD","N'djamena"}, {"COMOROS","Moroni"},
{"CONGO","Brazzaville"}, {"DJIBOUTI","Dijibouti"},
{"EGYPT","Cairo"}, {"EQUATORIAL GUINEA","Malabo"},
{"ERITREA","Asmara"}, {"ETHIOPIA","Addis Ababa"},
{"GABON","Libreville"}, {"THE GAMBIA","Banjul"},
{"GHANA","Accra"}, {"GUINEA","Conakry"},
{"GUINEA","-"}, {"BISSAU","Bissau"},
{"CETE D'IVOIR (IVORY COAST)","Yamoussoukro"},
{"KENYA","Nairobi"}, {"LESOTHO","Maseru"},
{"LIBERIA","Monrovia"}, {"LIBYA","Tripoli"},
{"MADAGASCAR","Antananarivo"}, {"MALAWI","Lilongwe"},
{"MALI","Bamako"}, {"MAURITANIA","Nouakchott"},
{"MAURITIUS","Port Louis"}, {"MOROCCO","Rabat"},
{"MOZAMBIQUE","Maputo"}, {"NAMIBIA","Windhoek"},
{"NIGER","Niamey"}, {"NIGERIA","Abuja"},
{"RWANDA","Kigali"}, {"SAO TOME E PRINCIPE","Sao Tome"},
{"SENEGAL","Dakar"}, {"SEYCHELLES","Victoria"},
{"SIERRA LEONE","Freetown"}, {"SOMALIA","Mogadishu"},
{"SOUTH AFRICA","Pretoria/Cape Town"}, {"SUDAN","Khartoum"},
{"SWAZILAND","Mbabane"}, {"TANZANIA","Dodoma"},
{"TOGO","Lome"}, {"TUNISIA","Tunis"},
{"UGANDA","Kampala"},
{"DEMOCRATIC REPUBLIC OF THE CONGO (ZAIRE)","Kinshasa"},
{"ZAMBIA","Lusaka"}, {"ZIMBABWE","Harare"},
// Asia
{"AFGHANISTAN","Kabul"}, {"BAHRAIN","Manama"},
{"BANGLADESH","Dhaka"}, {"BHUTAN","Thimphu"},
{"BRUNEI","Bandar Seri Begawan"}, {"CAMBODIA","Phnom Penh"},
{"CHINA","Beijing"}, {"CYPRUS","Nicosia"},
{"INDIA","New Delhi"}, {"INDONESIA","Jakarta"},
{"IRAN","Tehran"}, {"IRAQ","Baghdad"},
{"ISRAEL","Jerusalem"}, {"JAPAN","Tokyo"},
{"JORDAN","Amman"}, {"KUWAIT","Kuwait City"},
{"LAOS","Vientiane"}, {"LEBANON","Beirut"},
{"MALAYSIA","Kuala Lumpur"}, {"THE MALDIVES","Male"},
{"MONGOLIA","Ulan Bator"}, {"MYANMAR (BURMA)","Rangoon"},
{"NEPAL","Katmandu"}, {"NORTH KOREA","P'yongyang"},
{"OMAN","Muscat"}, {"PAKISTAN","Islamabad"},
{"PHILIPPINES","Manila"}, {"QATAR","Doha"},
{"SAUDI ARABIA","Riyadh"}, {"SINGAPORE","Singapore"},
{"SOUTH KOREA","Seoul"}, {"SRI LANKA","Colombo"},
{"SYRIA","Damascus"}, {"TAIWAN (REPUBLIC OF CHINA)","Taipei"},
{"THAILAND","Bangkok"}, {"TURKEY","Ankara"},
{"UNITED ARAB EMIRATES","Abu Dhabi"}, {"VIETNAM","Hanoi"},
{"YEMEN","Sana'a"},
// Australia and Oceania
{"AUSTRALIA","Canberra"}, {"FIJI","Suva"},
{"KIRIBATI","Bairiki"},
{"MARSHALL ISLANDS","Dalap-Uliga-Darrit"},
{"MICRONESIA","Palikir"}, {"NAURU","Yaren"},
{"NEW ZEALAND","Wellington"}, {"PALAU","Koror"},
{"PAPUA NEW GUINEA","Port Moresby"},
{"SOLOMON ISLANDS","Honaira"}, {"TONGA","Nuku'alofa"},
{"TUVALU","Fongafale"}, {"VANUATU","< Port-Vila"},
{"WESTERN SAMOA","Apia"},
// Eastern Europe and former USSR
{"ARMENIA","Yerevan"}, {"AZERBAIJAN","Baku"},
{"BELARUS (BYELORUSSIA)","Minsk"}, {"GEORGIA","Tbilisi"},
{"KAZAKSTAN","Almaty"}, {"KYRGYZSTAN","Alma-Ata"},
{"MOLDOVA","Chisinau"}, {"RUSSIA","Moscow"},
{"TAJIKISTAN","Dushanbe"}, {"TURKMENISTAN","Ashkabad"},
{"UKRAINE","Kyiv"}, {"UZBEKISTAN","Tashkent"},
// Europe
{"ALBANIA","Tirana"}, {"ANDORRA","Andorra la Vella"},
{"AUSTRIA","Vienna"}, {"BELGIUM","Brussels"},
{"BOSNIA","-"}, {"HERZEGOVINA","Sarajevo"},
{"CROATIA","Zagreb"}, {"CZECH REPUBLIC","Prague"},
{"DENMARK","Copenhagen"}, {"ESTONIA","Tallinn"},
{"FINLAND","Helsinki"}, {"FRANCE","Paris"},
{"GERMANY","Berlin"}, {"GREECE","Athens"},
{"HUNGARY","Budapest"}, {"ICELAND","Reykjavik"},
{"IRELAND","Dublin"}, {"ITALY","Rome"},
{"LATVIA","Riga"}, {"LIECHTENSTEIN","Vaduz"},
{"LITHUANIA","Vilnius"}, {"LUXEMBOURG","Luxembourg"},
{"MACEDONIA","Skopje"}, {"MALTA","Valletta"},
{"MONACO","Monaco"}, {"MONTENEGRO","Podgorica"},
{"THE NETHERLANDS","Amsterdam"}, {"NORWAY","Oslo"},
{"POLAND","Warsaw"}, {"PORTUGAL","Lisbon"},
{"ROMANIA","Bucharest"}, {"SAN MARINO","San Marino"},
{"SERBIA","Belgrade"}, {"SLOVAKIA","Bratislava"},
{"SLOVENIA","Ljujiana"}, {"SPAIN","Madrid"},
{"SWEDEN","Stockholm"}, {"SWITZERLAND","Berne"},
{"UNITED KINGDOM","London"}, {"VATICAN CITY","---"},
// North and Central America
{"ANTIGUA AND BARBUDA","Saint John's"}, {"BAHAMAS","Nassau"},
{"BARBADOS","Bridgetown"}, {"BELIZE","Belmopan"},
{"CANADA","Ottawa"}, {"COSTA RICA","San Jose"},
{"CUBA","Havana"}, {"DOMINICA","Roseau"},
{"DOMINICAN REPUBLIC","Santo Domingo"},
{"EL SALVADOR","San Salvador"}, {"GRENADA","Saint George's"},
{"GUATEMALA","Guatemala City"}, {"HAITI","Port-au-Prince"},
{"HONDURAS","Tegucigalpa"}, {"JAMAICA","Kingston"},
{"MEXICO","Mexico City"}, {"NICARAGUA","Managua"},
{"PANAMA","Panama City"}, {"ST. KITTS","-"},
{"NEVIS","Basseterre"}, {"ST. LUCIA","Castries"},
{"ST. VINCENT AND THE GRENADINES","Kingstown"},
{"UNITED STATES OF AMERICA","Washington, D.C."},
// South America
{"ARGENTINA","Buenos Aires"},
{"BOLIVIA","Sucre (legal)/La Paz(administrative)"},
{"BRAZIL","Brasilia"}, {"CHILE","Santiago"},
{"COLOMBIA","Bogota"}, {"ECUADOR","Quito"},
{"GUYANA","Georgetown"}, {"PARAGUAY","Asuncion"},
{"PERU","Lima"}, {"SURINAME","Paramaribo"},
{"TRINIDAD AND TOBAGO","Port of Spain"},
{"URUGUAY","Montevideo"}, {"VENEZUELA","Caracas"},
};
} ///:~
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//: com:bruceeckel:util:CountryCapitals.java
package com.bruceeckel.util;
public class CountryCapitals {
public static final String[][] pairs = {
// Afrique
{"ALGERIA","Algiers"}, {"ANGOLA","Luanda"},
{"BENIN","Porto-Novo"}, {"BOTSWANA","Gaberone"},
{"BURKINA FASO","Ouagadougou"}, {"BURUNDI","Bujumbura"},
{"CAMEROON","Yaounde"}, {"CAPE VERDE","Praia"},
{"CENTRAL AFRICAN REPUBLIC","Bangui"},
{"CHAD","N'djamena"}, {"COMOROS","Moroni"},
{"CONGO","Brazzaville"}, {"DJIBOUTI","Dijibouti"},
{"EGYPT","Cairo"}, {"EQUATORIAL GUINEA","Malabo"},
{"ERITREA","Asmara"}, {"ETHIOPIA","Addis Ababa"},
{"GABON","Libreville"}, {"THE GAMBIA","Banjul"},
{"GHANA","Accra"}, {"GUINEA","Conakry"},
{"GUINEA","-"}, {"BISSAU","Bissau"},
{"CETE D'IVOIR (IVORY COAST)","Yamoussoukro"},
{"KENYA","Nairobi"}, {"LESOTHO","Maseru"},
{"LIBERIA","Monrovia"}, {"LIBYA","Tripoli"},
{"MADAGASCAR","Antananarivo"}, {"MALAWI","Lilongwe"},
{"MALI","Bamako"}, {"MAURITANIA","Nouakchott"},
{"MAURITIUS","Port Louis"}, {"MOROCCO","Rabat"},
{"MOZAMBIQUE","Maputo"}, {"NAMIBIA","Windhoek"},
{"NIGER","Niamey"}, {"NIGERIA","Abuja"},
{"RWANDA","Kigali"}, {"SAO TOME E PRINCIPE","Sao Tome"},
{"SENEGAL","Dakar"}, {"SEYCHELLES","Victoria"},
{"SIERRA LEONE","Freetown"}, {"SOMALIA","Mogadishu"},
{"SOUTH AFRICA","Pretoria/Cape Town"}, {"SUDAN","Khartoum"},
{"SWAZILAND","Mbabane"}, {"TANZANIA","Dodoma"},
{"TOGO","Lome"}, {"TUNISIA","Tunis"},
{"UGANDA","Kampala"},
{"DEMOCRATIC REPUBLIC OF THE CONGO (ZAIRE)","Kinshasa"},
{"ZAMBIA","Lusaka"}, {"ZIMBABWE","Harare"},
// Asie
{"AFGHANISTAN","Kabul"}, {"BAHRAIN","Manama"},
{"BANGLADESH","Dhaka"}, {"BHUTAN","Thimphu"},
{"BRUNEI","Bandar Seri Begawan"}, {"CAMBODIA","Phnom Penh"},
{"CHINA","Beijing"}, {"CYPRUS","Nicosia"},
{"INDIA","New Delhi"}, {"INDONESIA","Jakarta"},
{"IRAN","Tehran"}, {"IRAQ","Baghdad"},
{"ISRAEL","Jerusalem"}, {"JAPAN","Tokyo"},
{"JORDAN","Amman"}, {"KUWAIT","Kuwait City"},
{"LAOS","Vientiane"}, {"LEBANON","Beirut"},
{"MALAYSIA","Kuala Lumpur"}, {"THE MALDIVES","Male"},
{"MONGOLIA","Ulan Bator"}, {"MYANMAR (BURMA)","Rangoon"},
{"NEPAL","Katmandu"}, {"NORTH KOREA","P'yongyang"},
{"OMAN","Muscat"}, {"PAKISTAN","Islamabad"},
{"PHILIPPINES","Manila"}, {"QATAR","Doha"},
{"SAUDI ARABIA","Riyadh"}, {"SINGAPORE","Singapore"},
{"SOUTH KOREA","Seoul"}, {"SRI LANKA","Colombo"},
{"SYRIA","Damascus"}, {"TAIWAN (REPUBLIC OF CHINA)","Taipei"},
{"THAILAND","Bangkok"}, {"TURKEY","Ankara"},
{"UNITED ARAB EMIRATES","Abu Dhabi"}, {"VIETNAM","Hanoi"},
{"YEMEN","Sana'a"},
// Australie et Océanie
{"AUSTRALIA","Canberra"}, {"FIJI","Suva"},
{"KIRIBATI","Bairiki"},
{"MARSHALL ISLANDS","Dalap-Uliga-Darrit"},
{"MICRONESIA","Palikir"}, {"NAURU","Yaren"},
{"NEW ZEALAND","Wellington"}, {"PALAU","Koror"},
{"PAPUA NEW GUINEA","Port Moresby"},
{"SOLOMON ISLANDS","Honaira"}, {"TONGA","Nuku'alofa"},
{"TUVALU","Fongafale"}, {"VANUATU","< Port-Vila"},
{"WESTERN SAMOA","Apia"},
// Europe de l'Est et ancienne URSS
{"ARMENIA","Yerevan"}, {"AZERBAIJAN","Baku"},
{"BELARUS (BYELORUSSIA)","Minsk"}, {"GEORGIA","Tbilisi"},
{"KAZAKSTAN","Almaty"}, {"KYRGYZSTAN","Alma-Ata"},
{"MOLDOVA","Chisinau"}, {"RUSSIA","Moscow"},
{"TAJIKISTAN","Dushanbe"}, {"TURKMENISTAN","Ashkabad"},
{"UKRAINE","Kyiv"}, {"UZBEKISTAN","Tashkent"},
// Europe
{"ALBANIA","Tirana"}, {"ANDORRA","Andorra la Vella"},
{"AUSTRIA","Vienna"}, {"BELGIUM","Brussels"},
{"BOSNIA","-"}, {"HERZEGOVINA","Sarajevo"},
{"CROATIA","Zagreb"}, {"CZECH REPUBLIC","Prague"},
{"DENMARK","Copenhagen"}, {"ESTONIA","Tallinn"},
{"FINLAND","Helsinki"}, {"FRANCE","Paris"},
{"GERMANY","Berlin"}, {"GREECE","Athens"},
{"HUNGARY","Budapest"}, {"ICELAND","Reykjavik"},
{"IRELAND","Dublin"}, {"ITALY","Rome"},
{"LATVIA","Riga"}, {"LIECHTENSTEIN","Vaduz"},
{"LITHUANIA","Vilnius"}, {"LUXEMBOURG","Luxembourg"},
{"MACEDONIA","Skopje"}, {"MALTA","Valletta"},
{"MONACO","Monaco"}, {"MONTENEGRO","Podgorica"},
{"THE NETHERLANDS","Amsterdam"}, {"NORWAY","Oslo"},
{"POLAND","Warsaw"}, {"PORTUGAL","Lisbon"},
{"ROMANIA","Bucharest"}, {"SAN MARINO","San Marino"},
{"SERBIA","Belgrade"}, {"SLOVAKIA","Bratislava"},
{"SLOVENIA","Ljujiana"}, {"SPAIN","Madrid"},
{"SWEDEN","Stockholm"}, {"SWITZERLAND","Berne"},
{"UNITED KINGDOM","London"}, {"VATICAN CITY","---"},
// Amérique du Nord et Amérique Centrale
{"ANTIGUA AND BARBUDA","Saint John's"}, {"BAHAMAS","Nassau"},
{"BARBADOS","Bridgetown"}, {"BELIZE","Belmopan"},
{"CANADA","Ottawa"}, {"COSTA RICA","San Jose"},
{"CUBA","Havana"}, {"DOMINICA","Roseau"},
{"DOMINICAN REPUBLIC","Santo Domingo"},
{"EL SALVADOR","San Salvador"}, {"GRENADA","Saint George's"},
{"GUATEMALA","Guatemala City"}, {"HAITI","Port-au-Prince"},
{"HONDURAS","Tegucigalpa"}, {"JAMAICA","Kingston"},
{"MEXICO","Mexico City"}, {"NICARAGUA","Managua"},
{"PANAMA","Panama City"}, {"ST. KITTS","-"},
{"NEVIS","Basseterre"}, {"ST. LUCIA","Castries"},
{"ST. VINCENT AND THE GRENADINES","Kingstown"},
{"UNITED STATES OF AMERICA","Washington, D.C."},
// Amérique du Sud
{"ARGENTINA","Buenos Aires"},
{"BOLIVIA","Sucre (legal)/La Paz(administrative)"},
{"BRAZIL","Brasilia"}, {"CHILE","Santiago"},
{"COLOMBIA","Bogota"}, {"ECUADOR","Quito"},
{"GUYANA","Georgetown"}, {"PARAGUAY","Asuncion"},
{"PERU","Lima"}, {"SURINAME","Paramaribo"},
{"TRINIDAD AND TOBAGO","Port of Spain"},
{"URUGUAY","Montevideo"}, {"VENEZUELA","Caracas"},
};
} ///:~
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This is simply a two-dimensional array of
String
data[48].
Here’s a simple test using the fill( ) methods and
generators:
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Il s'agit juste d'un tableau bidimensionnel de
String[48]. Voici un
simple test illustrant les méthodes fill() et les générateurs :
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//: c09:FillTest.java
import com.bruceeckel.util.*;
import java.util.*;
public class FillTest {
static Generator sg =
new Arrays2.RandStringGenerator(7);
public static void main(String[] args) {
List list = new ArrayList();
Collections2.fill(list, sg, 25);
System.out.println(list + "\n");
List list2 = new ArrayList();
Collections2.fill(list2,
Collections2.capitals, 25);
System.out.println(list2 + "\n");
Set set = new HashSet();
Collections2.fill(set, sg, 25);
System.out.println(set + "\n");
Map m = new HashMap();
Collections2.fill(m, Collections2.rsp, 25);
System.out.println(m + "\n");
Map m2 = new HashMap();
Collections2.fill(m2,
Collections2.geography, 25);
System.out.println(m2);
}
} ///:~
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//: c09:FillTest.java
import com.bruceeckel.util.*;
import java.util.*;
public class FillTest {
static Generator sg =
new Arrays2.RandStringGenerator(7);
public static void main(String[] args) {
List list = new ArrayList();
Collections2.fill(list, sg, 25);
System.out.println(list + "\n");
List list2 = new ArrayList();
Collections2.fill(list2,
Collections2.capitals, 25);
System.out.println(list2 + "\n");
Set set = new HashSet();
Collections2.fill(set, sg, 25);
System.out.println(set + "\n");
Map m = new HashMap();
Collections2.fill(m, Collections2.rsp, 25);
System.out.println(m + "\n");
Map m2 = new HashMap();
Collections2.fill(m2,
Collections2.geography, 25);
System.out.println(m2);
}
} ///:~
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With these tools you can easily test the
various containers by filling them with interesting
data.
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Avec ces outils vous pourrez facilement tester les différents conteneurs en
les remplissant avec des données intéressantes.
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Container disadvantage:
unknown type
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L'inconvénient des conteneurs : le type est inconnu
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The “disadvantage” to using
the Java containers is that you lose type information when you put an object
into a container. This happens because the programmer of that container class
had no idea what specific type you wanted to put in the container, and making
the container hold only your type would prevent it from being a general-purpose
tool. So instead, the container holds references to Object, which is the
root of all the classes so it holds any type. (Of course, this doesn’t
include primitive types, since they aren’t inherited from anything.) This
is a great solution, except:
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L'« inconvénient » des conteneurs Java est qu'on perd
l'information du type lorsqu'un objet est stocké dedans, ce qui est tout à fait normal puisque le
programmeur de la classe conteneur n'a aucune idée du type spécifique qu'on veut stocker dans le
conteneur, et que fournir un conteneur qui ne sache stocker qu'un seul type d'objets irait à
l'encontre du but de généricité de l'outil conteneur. C'est pourquoi les conteneurs stockent des
références sur des Objects, la classe de base de toutes les classes, afin de
pouvoir stocker n'importe quel type d'objet (à l'exception bien sûr des types scalaires, qui ne
dérivent aucune classe). Cette solution est formidable dans sa conception, sauf sur deux
points :
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- Since the type information
is thrown away when you put an object reference into a container, there’s
no restriction on the type of object that can be put into your container, even
if you mean it to hold only, say, cats. Someone could just as easily put a dog
into the
container.
- Since the
type information is lost, the only thing the container knows that it holds is a
reference to an object. You must perform a cast to the correct type before you
use it.
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- Puisque l'information de type est ignorée lorsqu'on stocke une référence
dans un conteneur, on ne peut placer aucune restriction sur le type de l'objet stocké dans le
conteneur, même si on l'a créé pour ne contenir, par exemple, que des chats. Quelqu'un pourrait
très bien ajouter un chien dans le conteneur.
- Puisque l'information de type est perdue, la seule chose que le conteneur
sache est qu'il contient une référence sur un objet. Il faut réaliser un transtypage sur le type
adéquat avant de l'utiliser.
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On the up side, Java
won’t let you misuse the objects that you put into a container. If
you throw a dog into a container of cats and then try to treat everything in the
container as a cat, you’ll get a run-time exception when you pull the dog
reference out of the cat container and try to cast it to a cat.
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Du côté des choses positives, Java ne permettra pas une mauvaise
utilisation des objets stockés dans un conteneur. Si on stocke un chien dans le conteneur de chats
et qu'on essaie ensuite de traiter tous les objets du conteneur comme un chat, Java générera une
run-time exception lors de la tentative de transtypage en chat de la référence sur le
chien.
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Here’s an example using the basic
workhorse container, ArrayList. For starters, you can think of
ArrayList as “an array that automatically expands itself.”
Using an ArrayList is straightforward: create one, put objects in using
add( ), and later get
them out with get( )
using an index—just like you would with an array but without the
square
brackets[49].
ArrayList also has a method
size( ) to let you
know how many elements have been added so you don’t inadvertently run off
the end and cause an exception.
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Voici un exemple utilisant le conteneur à tout faire
ArrayList. Les débutants peuvent considérer une ArrayList comme
« un tableau qui se redimensionne de lui-même ». L'utilisation d'une
ArrayList est aisée : il suffit de la créer, d'y ajouter des éléments avec la
méthode add(), et d'y accéder par la suite grâce à la
méthode get() en utilisant un index - comme pour un tableau, mais sans les
crochets [49].
ArrayList propose aussi une méthode size() qui permet de
savoir combien d'éléments ont été stockés afin de ne pas dépasser les frontières et causer une
exception.
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First, Cat and Dog classes
are created:
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Tout d'abord, nous créons les classes Cat et
Dog :
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//: c09:Cat.java
public class Cat {
private int catNumber;
Cat(int i) { catNumber = i; }
void print() {
System.out.println("Cat #" + catNumber);
}
} ///:~
//: c09:Dog.java
public class Dog {
private int dogNumber;
Dog(int i) { dogNumber = i; }
void print() {
System.out.println("Dog #" + dogNumber);
}
} ///:~
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//: c09:Cat.java
public class Cat {
private int catNumber;
Cat(int i) { catNumber = i; }
void print() {
System.out.println("Cat #" + catNumber);
}
} ///:~
//: c09:Dog.java
public class Dog {
private int dogNumber;
Dog(int i) { dogNumber = i; }
void print() {
System.out.println("Dog #" + dogNumber);
}
} ///:~
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Cats and Dogs are placed
into the container, then pulled out:
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Des Cats et des Dogs sont placés dans le
conteneur, puis extraits :
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//: c09:CatsAndDogs.java
// Simple container example.
import java.util.*;
public class CatsAndDogs {
public static void main(String[] args) {
ArrayList cats = new ArrayList();
for(int i = 0; i < 7; i++)
cats.add(new Cat(i));
// Not a problem to add a dog to cats:
cats.add(new Dog(7));
for(int i = 0; i < cats.size(); i++)
((Cat)cats.get(i)).print();
// Dog is detected only at run-time
}
} ///:~
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//: c09:CatsAndDogs.java
// Exemple simple avec un conteneur.
import java.util.*;
public class CatsAndDogs {
public static void main(String[] args) {
ArrayList cats = new ArrayList();
for(int i = 0; i < 7; i++)
cats.add(new Cat(i));
// Ce n'est pas un problème d'ajouter un chien parmi les chats :
cats.add(new Dog(7));
for(int i = 0; i < cats.size(); i++)
((Cat)cats.get(i)).print();
// Le chien est détecté seulement lors de l'exécution.
}
} ///:~
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