模拟植树活动，编写一个java应用程序，在主线程中创建3个线程:"挖树坑"、"栽树苗"、"浇水"

* 实现他们之间的协同合作

* 要求"浇水"线程占有CPU资源后立即等待"栽树苗"线程栽完树后才能开始浇水，

* 而"栽树苗"线程占有CPU资源后则一直等待"挖树坑"线程挖完树坑后才能开始栽树苗

* 关于线程交互过程的信息能够在屏幕上进行提示

* 使用join()方法实现线程交互 */

-Simulated tree-planting activities, write a java application, in the main thread to create three threads: " dig Pits,"　" planted trees" , " water" * achieve* their collaboration between the requirements of " water"　thread possession immediately after the CPU resources, waiting for " planted trees"　End of thread tree planting can begin watering,* and " planted trees"　threads share CPU resources while waiting after the " dig Pits"　thread before you start digging End Pits* planted saplings on the thread interaction information can be prompted on the screen* use the join () method to achieve interactive thread* /