Abstract Factory in Java
Why read if you can watch?
Watch Abstract Factory's video tutorialAbstract Factory classes are often implemented with Factory Methods, but they can also be implemented using Prototype. Abstract Factory might store a set of Prototypes from which to clone and return product objects. Factory Method: creation through inheritance. Prototype: creation through delegation. Virtual constructor: defer choice of object to create until run-time.
public class FactoryFmProto
{
static class Expression
{
protected String str;
public Expression(String s)
{
str = s;
}
public Expression cloan()
{
return null;
}
public String toString()
{
return str;
}
}
static abstract class Factory
{
protected Expression prototype = null;
public Expression makePhrase()
{
return prototype.cloan();
}
public abstract Expression makeCompromise();
public abstract Expression makeGrade();
}
static class PCFactory extends Factory
{
public PCFactory()
{
prototype = new PCPhrase();
}
public Expression makeCompromise()
{
return new Expression("\"do it your way, any way, or no way\"");
}
public Expression makeGrade()
{
return new Expression("\"you pass, self-esteem intact\"");
}
}
static class NotPCFactory extends Factory
{
public NotPCFactory()
{
prototype = new NotPCPhrase();
}
public Expression makeCompromise()
{
return new Expression("\"my way, or the highway\"");
}
public Expression makeGrade()
{
return new Expression("\"take test, deal with the results\"");
}
}
public static void main(String[] args)
{
Factory factory;
if (args.length > 0)
factory = new PCFactory();
else
factory = new NotPCFactory();
for (int i = 0; i < 3; i++)
System.out.print(factory.makePhrase() + " ");
System.out.println();
System.out.println(factory.makeCompromise());
System.out.println(factory.makeGrade());
}
static class PCPhrase extends Expression
{
static String[] list =
{
"\"animal companion\"", "\"vertically challenged\"",
"\"factually inaccurate\"", "\"chronologically gifted\""
};
private static int next = 0;
public PCPhrase()
{
super(list[next]);
next = (next + 1) % list.length;
}
public Expression cloan()
{
return new PCPhrase();
}
}
static class NotPCPhrase extends Expression
{
private static String[] list =
{
"\"pet\"", "\"short\"", "\"lie\"", "\"old\""
};
private static int next = 0;
public NotPCPhrase()
{
super(list[next]);
next = (next + 1) % list.length;
}
public Expression cloan()
{
return new NotPCPhrase();
}
}
}
D:\Java\patterns> java FactoryFmProto
"short" "lie" "old"
"my way, or the highway"
"take test, deal with the results"
D:\Java\patterns> java FactoryFmProto 1
"vertically challenged" "factually inaccurate" "chronologically gifted"
"do it your way, any way, or no way"
"you pass, self-esteem intact"
