Design patterns
Mallmetod
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Mallmetodimplementering i java
Mallmetodmönster är ett beteendemönstermönster som definierar programskelettet för en algoritm i en operation och skjuter upp några steg till underklasser.
Strukturera:
Viktiga anmärkningar:
- Mallmetod använder arv
- Mallmetoden som implementeras av basklassen bör inte åsidosättas. På detta sätt styrs algoritmens struktur av superklassen och detaljerna implementeras i underklasserna
Kodexempel:
import java.util.List;
class GameRule{
}
class GameInfo{
String gameName;
List<String> players;
List<GameRule> rules;
}
abstract class Game{
protected GameInfo info;
public Game(GameInfo info){
this.info = info;
}
public abstract void createGame();
public abstract void makeMoves();
public abstract void applyRules();
/* playGame is template method. This algorithm skeleton can't be changed by sub-classes. sub-class can change
the behaviour only of steps like createGame() etc. */
public void playGame(){
createGame();
makeMoves();
applyRules();
closeGame();
}
protected void closeGame(){
System.out.println("Close game:"+this.getClass().getName());
System.out.println("--------------------");
}
}
class Chess extends Game{
public Chess(GameInfo info){
super(info);
}
public void createGame(){
// Use GameInfo and create Game
System.out.println("Creating Chess game");
}
public void makeMoves(){
System.out.println("Make Chess moves");
}
public void applyRules(){
System.out.println("Apply Chess rules");
}
}
class Checkers extends Game{
public Checkers(GameInfo info){
super(info);
}
public void createGame(){
// Use GameInfo and create Game
System.out.println("Creating Checkers game");
}
public void makeMoves(){
System.out.println("Make Checkers moves");
}
public void applyRules(){
System.out.println("Apply Checkers rules");
}
}
class Ludo extends Game{
public Ludo(GameInfo info){
super(info);
}
public void createGame(){
// Use GameInfo and create Game
System.out.println("Creating Ludo game");
}
public void makeMoves(){
System.out.println("Make Ludo moves");
}
public void applyRules(){
System.out.println("Apply Ludo rules");
}
}
public class TemplateMethodPattern{
public static void main(String args[]){
System.out.println("--------------------");
Game game = new Chess(new GameInfo());
game.playGame();
game = new Ludo(new GameInfo());
game.playGame();
game = new Checkers(new GameInfo());
game.playGame();
}
}
Förklaring:
Game
är enabstract
superklass som definierar en mallmetod:playGame()
playGame()
ofplayGame()
definieras i basklass:Game
Underklasser som
Chess, Ludo
ochCheckers
kan inte ändra skelettet iplayGame()
. Men de kan ändra beteendet hos vissa steg somcreateGame(); makeMoves(); applyRules();
produktion:
--------------------
Creating Chess game
Make Chess moves
Apply Chess rules
Close game:Chess
--------------------
Creating Ludo game
Make Ludo moves
Apply Ludo rules
Close game:Ludo
--------------------
Creating Checkers game
Make Checkers moves
Apply Checkers rules
Close game:Checkers
--------------------
Modified text is an extract of the original Stack Overflow Documentation
Licensierat under CC BY-SA 3.0
Inte anslutet till Stack Overflow