Unit 3 - Demonstration of ADT

PrepareJobAction.java

class Job {
    private final long interval;
    private final String tag;

    Job(Builder builder) {
        this.interval = builder.interval;
        this.tag = builder.tag;
    }

    @Retention(RetentionPolicy.SOURCE)
    @interface Interval {
        long WEEKLY = TimeUnit.DAYS.toMillis(7);
    }
    
    static class Builder {
        private long interval;
        private String tag;

        public Builder repeat(long interval) {
            this.interval = interval;
            return this;
        }

        public Builder tag(String tag) {
            this.tag = tag;
            return this;
        }
        
        public Job build() {
            return new Job(this);
        }
    }
}
abstract class Scheduler {
    abstract long enqueue(Job job);
} 

class PrepareJobAction {
    private final Scheduler scheduler;

    PrepareJobAction(Scheduler scheduler) {
        this.scheduler = scheduler;
    }

    public int prepare() {
        Job job = new Job.Builder()
                .tag("By milk")
                .repeat(Job.Interval.WEEKLY)
                .build();
        long jobId = scheduler.enqueue(job);
        return jobId;
    }
}