英语翻译这是一个java编程题,题目是英文的,想要翻译,如果能完成程序编写,追加100分Pi can be calcul

英语翻译这是一个java编程题,题目是英文的,想要翻译,如果能完成程序编写,追加100分Pi can be calculated using the following sum,which is an approximation to Pi/4 :PiSum = 1 - 1/3 + 1/5 - 1/7 + ...+ (-1)^n / (2*n + 1)1) Write two methods that return PiSum for a specified value of n,one methodusing recursion and the other using iteration to do the sum.Hint:instead of calculating (-1)^n,you can check whether the nth term isnegative by checking whether n%2 (i.e.n modulo 2) is 1.Assume that the methods are always called with a non-negative value of n,so youdon't need to worry about dealing with invalid parameter values.2) Show the additional code you would add to the above methods to throw anexception if n is less than zero (you don't need to rewrite the whole method).Theexception handler should generate an error message saying that the number of termsin the sum must not be negative.Write a code fragment (i.e.it doesn't need to be a complete method) that invokesone of the methods for calculating Pi and prints out the result if the method returnscorrectly,or else catches an exception and prints out the error message returned.3) When calculating Pi using the given formula,suppose that instead of passing aparameter specifying the number of terms n in the sum,we instead want to pass aparameter that specifies a precision value.The sum should terminate at the first valuen for which the absolute value of the nth term in the sum,i.e.1/(2*n+1) is less thanthe specified precision.Show how this can be implemented using a do loop.