设计一个名为StopWatch的类，该类包括：具有访问器方法的私有数据域startTime和endTime；一个无参构造方法，使用当前时间来初始化startTime；一个名为start（）方法，将startTime重设为当前时间；一个名为stop()方法，将endTime设置为当前时间；一个名为getElapsedTime()的方法，以毫秒为单位返回秒表记录的流逝时间。画出该类的UML图并实现这个类。并编写一个测试程序，用于测量使用选择排序对100 0000个数字进行排序的执行时间。-Design called StopWatch class that includes: private data fields startTime and endTime have accessor methods　a constructor with no arguments, the current time to initialize startTime　a method named start (), reset the startTime current time　a stop () method called the endTime set to the current time　a method called getElapsedTime () to return a stopwatch milliseconds elapsed time. Draw UML class diagram and implement this class. And write a test procedure for measuring the use of selection sort 100 0000 numbers ordered the execution time.