线程执行顺序怎么控制？

publicclassThreadTest {
publicstaticvoidmain(String[] args) {
Threadspring=newThread(newSeasonThreadTask("春天"));
Threadsummer=newThread(newSeasonThreadTask("夏天"));
运行结果：Threadautumn=newThread(newSeasonThreadTask("秋天"));
try {
//春天线程先启动spring.start();
//主线程等待线程spring执行完，再往下执行spring.join();
//夏天线程再启动summer.start();
//主线程等待线程summer执行完，再往下执行summer.join();
//秋天线程最后启动autumn.start();
//主线程等待线程autumn执行完，再往下执行autumn.join();
        } catch (InterruptedExceptione) {
e.printStackTrace();
        }
    }
}
classSeasonThreadTaskimplementsRunnable {
privateStringname;
publicSeasonThreadTask(Stringname){
this.name=name;
    }
@Overridepublicvoidrun() {
for (inti=1; i<4; i++) {
System.out.println(this.name+"来了: "+i+"次");
try {
Thread.sleep(100);
            } catch (InterruptedExceptione) {
e.printStackTrace();
            }
         }
    }
}

春天来了: 1次春天来了: 2次春天来了: 3次夏天来了: 1次夏天来了: 2次夏天来了: 3次秋天来了: 1次秋天来了: 2次秋天来了: 3次