Each of the counter-controlled for loops we used in this chapter’s examples can be implemented using IntStream’s rangeClosed method to produce a range of values, then using IntStream’s forEach method to specify a lambda to execute for each value. The lambda argument to forEach could, for example, call method factorial (Figs. 18.3 –18.4) or method fibonacci (Fig. 18.5 ) and display the result.

Figs. 18.3

Figs. 18.4

Figs. 18.5

1 // Fig. 18.3: Factorial Calculator.java // Recursive factorial method. 2 3 4 public class Factorial Calculator { 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 } 0! = 1 1!= 1 2!= 2 3! = 6 // recursive method factorial (assumes its parameter is >= 0) public static long factorial (long number) { } 20! 21! = } 4! = 24 5! = 120 if (number