Chain of responsibility automatic generator

Question

i have 8 handler class, is there a way i can create the chain dynamically in java?

What I mean, if I have two classes right now like:

HandlerA

HandlerB

HandlerChain

HanddlerChain will create the chain, HandlerA->HandlerB, (using loop read all class names from the folder)

when i add HandlerC then it is automatically add without any interaction and the chain become, HandlerA->HandlerB->HandlerC.

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So if I had String className = "HandlerA"

What is the way i make instance of HandlerA.class using the privaice String?

Welcome to SO. What did you try so far? We are not going to do it for you. You have to come up with your own solution — D. Lawrence, Dec 11 '19 at 10:15
With the help of inheritance? Use a super class that adds the instance to the chain... — Jean-Baptiste Yunès, Dec 11 '19 at 10:17
@D.Lawrence i know how chain of responsibility work but what i want is give class name as string then it create the instance of that class. — Ahmad Saleh, Dec 11 '19 at 10:20
what folder? source folder? running app container folder? Your question is way too broad for now. Edit it to add more details on what you are doing/trying to do. — jhamon, Dec 11 '19 at 10:24
Naming a pattern doesn't explain what **you** are doing and how **you** are implementing it.If you don't want to answer the questions of people trying to help you, maybe you are not on the right place — jhamon, Dec 11 '19 at 10:42
@jhamon my question not about the patter. about automaic creation of the chain. when add a new handler the system will add it without changing of the chain creation code. — Ahmad Saleh, Dec 11 '19 at 10:45

Ahmad Saleh · Accepted Answer · 2019-12-11T12:58:00.900

    File folder = new File("JavaClassesPath");
    ArrayList<String> all = new ArrayList<>();
    for (final File fileEntry : folder.listFiles()) {
        if (!fileEntry.isDirectory()) {
            all.add(fileEntry.getName().substring(0, fileEntry.getName().lastIndexOf('.')));
        }
    }

    String className = "PackageName";

    for (String s: all) {
        if (!s.equals("AbstractClassName")) {
            Class<?> clazz = Class.forName(className + '.' + s);
            Constructor<?> ctor = clazz.getConstructor();
            Object object = ctor.newInstance();
            allHandlers.add((RequestHandler) object);
        }
    }

    for(int i=0; i<allHandlers.size()-1; i++){
        allHandlers.get(i).setNextHandler(allHandlers.get(i+1));
    }

Chain of responsibility automatic generator

1 Answers1