a$.$ Implement a Java class enabling users to input multiple products prices until they input the sentinel value $9999.$ If a product price falls outside the range of $0$ to $$1000,$ provide a relevant message and disregard the price. Upon completion of price input, display the count of product prices entered less than $$100,$ the highest price, the lowest price, and the arithmetic average. Save this file as ProductPrice.java.

$$

b$.$ Develop an application$/$project called ProductPriceTest.java with a main method and an instance to utilize the ProductPrice class.

$$