Quartz怎么设置多任务

     public class Test_1 {    public Scheduler createScheduler() throws Exception {        SchedulerFactory sf = new StdSchedulerFactory("Quartz.properties");    Scheduler scheduler = sf.getScheduler();    scheduler.scheduleJob(createJobDetail_1(), createCronTrigger_1());[color=#FF0000]// 下面这一行，是我添加的另外一个作用的调度计划，问题就出在这[/color]    scheduler.scheduleJob(createJobDetail_2(), createCronTrigger_2());    return scheduler;}private JobDetail createJobDetail_1() {    JobDetail job = new JobDetail(DemoJob_1.class.getName(),            Scheduler.DEFAULT_GROUP, DemoJob_1.class);    return job;}private CronTrigger createCronTrigger_1() throws ParseException {    CronTrigger trigger = new org.quartz.CronTrigger("DEFAULT", null);    trigger.setJobName(DemoJob_1.class.getName());    trigger.setCronExpression(" 0/5 * * * * ? ");    return trigger;}private JobDetail createJobDetail_2() {    JobDetail job = new JobDetail(DemoJob_2.class.getName(),            Scheduler.DEFAULT_GROUP, DemoJob_2.class);    return job;}private CronTrigger createCronTrigger_2() throws ParseException {    CronTrigger trigger = new org.quartz.CronTrigger("DEFAULT", null);    trigger.setJobName(DemoJob_2.class.getName());    trigger.setCronExpression(" 0/15 * * * * ? ");    return trigger;}}   public class DemoJob_1 implements Job {        @Override    public void execute(JobExecutionContext arg0) throws JobExecutionException {        System.out.println("DemoJob_1 demo output :" + new Date());    }}public class DemoJob_2 implements Job {    @Override    public void execute(JobExecutionContext arg0) throws JobExecutionException {        System.out.println("DemoJob_2 demo output :" + new Date());    }}public class DemoTest {    public static void main(String [] args) throws SchedulerException, Exception{        Test_1 test_1 = new Test_1();         test_1.createScheduler().start();    }}