// patterns/trash/DynaFactory.java

// (c)2021 MindView LLC: see Copyright.txt

// We make no guarantees that this code is fit for any purpose.

// Visit http://OnJava8.com for more book information.

// Dynamic discovery of Trash types.

package patterns.trash;

import java.util.*;

import java.util.function.*;

import java.lang.reflect.*;

public class DynaFactory {

private Map<String, Constructor> constructors =

new HashMap<>();

private String packageName;

public DynaFactory(String packageName) {

this.packageName = packageName;

}

@SuppressWarnings("unchecked")

public

<T extends Trash> T create(TrashInfo info) {

try {

String typename =

"patterns." + packageName + "." + info.type;

return (T)constructors.computeIfAbsent(

typename, this::findConstructor

).newInstance(info.data);

} catch(Exception e) {

throw new RuntimeException(

"Cannot create() Trash: " + info, e);

}

}

private

Constructor findConstructor(String typename) {

try {

System.out.println("Loading " + typename);

return Class.forName(typename)

.getConstructor(double.class);

} catch(Exception e) {

throw new RuntimeException(

"Trash(double) Constructor Not Found: " +

typename, e);

}

}

}