建立main函数，建立tostring方法，并练习for loop(Add a toString() method in the Dog class, such that this method provides a String representation of the Dog object. This method should return all the Dog attributes in a String. ii) Write a new test program called DogTest2, such that it creates an array of 6 Dog objects. Using a for loop, the test program should loop through the array of Dogs and print out the details of each Dog object1.)