How to pass instance variables into Quartz job?

you can put your instance in the schedulerContext.When you are going to schedule the job ,just before that you can do below:

getScheduler().getContext().put("externalInstance", externalInstance);

Your job class would be like below:

public class SimpleJob implements Job {
    @Override
    public void execute(JobExecutionContext context)
            throws JobExecutionException {
        SchedulerContext schedulerContext = null;
        try {
            schedulerContext = context.getScheduler().getContext();
        } catch (SchedulerException e1) {
            e1.printStackTrace();
        }
        ExternalInstance externalInstance =
            (ExternalInstance) schedulerContext.get("externalInstance");

        float avg = externalInstance.calculateAvg();
    }
}

If you are using Spring ,you can actually using spring’s support to inject the whole applicationContext like answered in the Link