If I have 2 classes, "A" and "B", how can I create a generic factory so I will only need to pass the class name as a string to receive an instance?
Example:
public static void factory(String name) {
// An example of an implmentation I would need, this obviously doesn't work
return new name.CreateClass();
}
Thanks!
Joel
You can assign a string literal directly into a String variable, instead of calling the constructor to create a String instance. The '+' operator is overloaded to concatenate two String operands. '+' does not work on any other objects such as Point and Circle . String is immutable.
Class c= Class.forName(className);
return c.getDeclaredConstructor().newInstance();//assuming you aren't worried about constructor .
For invoking constructor with argument
public static Object createObject(Constructor constructor,
Object[] arguments) {
System.out.println("Constructor: " + constructor.toString());
Object object = null;
try {
object = constructor.newInstance(arguments);
System.out.println("Object: " + object.toString());
return object;
} catch (InstantiationException e) {
//handle it
} catch (IllegalAccessException e) {
//handle it
} catch (IllegalArgumentException e) {
//handle it
} catch (InvocationTargetException e) {
//handle it
}
return object;
}
}
have a look
You may take a look at Reflection:
import java.awt.Rectangle;
public class SampleNoArg {
public static void main(String[] args) {
Rectangle r = (Rectangle) createObject("java.awt.Rectangle");
System.out.println(r.toString());
}
static Object createObject(String className) {
Object object = null;
try {
Class classDefinition = Class.forName(className);
object = classDefinition.newInstance();
} catch (InstantiationException e) {
System.out.println(e);
} catch (IllegalAccessException e) {
System.out.println(e);
} catch (ClassNotFoundException e) {
System.out.println(e);
}
return object;
}
}
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