应用Java中线程的概念写一个Java程序（包括一个测试线程程序类TestThread，一个Thread类的子类PrintThread）。在测试程序中用子类PrintThread创建2个线程，使得其中一个线程运行时打印10次“线程1正在运行”，另一个线程运行时打印5次“线程2正在运行”。-Applications in Java thread concept to write a Java program (including the class TestThread a test multithreaded programs, a subclass of the Thread class PrintThread). Subclass PrintThread in the test procedures used to create two threads, making a thread run print 10 "thread is running and another thread is running print 5" thread is running.