# java 程序：使用遞歸查找給定數字的階乘 > 原文： [https://beginnersbook.com/2014/01/java-program-to-find-factorial-of-a-given-number-using-recursion/](https://beginnersbook.com/2014/01/java-program-to-find-factorial-of-a-given-number-using-recursion/) 在這里，我們將**編寫程序，使用遞歸**找出數字的階乘。 **程序 1：** 程序將提示用戶輸入數字。一旦用戶提供輸入，程序將計算所提供輸入數的階乘。 ```java /** * @author: BeginnersBook.com * @description: User would enter the 10 elements * and the program will store them into an array and * will display the sum of them. */ import java.util.Scanner; class FactorialDemo{ public static void main(String args[]){ //Scanner object for capturing the user input Scanner scanner = new Scanner(System.in); System.out.println("Enter the number:"); //Stored the entered value in variable int num = scanner.nextInt(); //Called the user defined function fact int factorial = fact(num); System.out.println("Factorial of entered number is: "+factorial); } static int fact(int n) { int output; if(n==1){ return 1; } //Recursion: Function calling itself!! output = fact(n-1)* n; return output; } } ``` 輸出： ```java Enter the number: 5 Factorial of entered number is: 120 ``` **程序 2：** 如果您不想要用戶干預并且只想在程序中指定數字，請參考此示例。 ```java class FactorialDemo2{ public static void main(String args[]){ int factorial = fact(4); System.out.println("Factorial of 4 is: "+factorial); } static int fact(int n) { int output; if(n==1){ return 1; } //Recursion: Function calling itself!! output = fact(n-1)* n; return output; } } ``` 輸出： ```java Factorial of 4 is: 24 ```