case statements in Java

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Converting many 'if else' statements to a cleaner approach 7 answers

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One of the solution is to use polymorphism to handle triggers differently. For instance, you could declare the Trigger interface and have several implementations. In this case, when you need a new trigger type, you just implement this interface and don't touch the existing code:

public interface Trigger {
    TriggerResultInterface execute(TriggerEventHelper eventHelper);
}

public class MetaTrigger implements Trigger {
    @Override
    TriggerResultInterface execute(TriggerEventHelper eventHelper) {
        // do meta trigger work here
    }
}

public class DataTrigger implements Trigger {
    @Override
    TriggerResultInterface execute(TriggerEventHelper eventHelper) {
        // do data trigger work here
    }
}

// ...

public TriggerResultInterface executeTriggerJob(TriggerEventHelper eventHelper) {
    eventHelper.getTrigger().execute(eventHelper);
}

In this case it will be impossible to add a new trigger type and not implement its behaviour.

If you need a default implementation, you can use a base class instead of the interface (in Java 8 you can add a default implementation right into the interface).

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