java - 如何从 for 循环中返回值？

Question

这是我的代码:

import java.util.*;

public class factorialdisplay {
  // Main Method. Prints out results of methods below.
  public static void main(String[] args) {
    Scanner console = new Scanner(System.in);

    // Asks user for input
    System.out.println("Please enter a number: ");
    int n = console.nextInt();

    for (int i = 0; i <= n; ++i) {
      System.out.println(i + "! = " + factorial(n));
    }
  }

  public static int factorial (int n) {
    int f = 1;
    for (int i = 1; i <= n; ++i) {
      f *= i;
      return f;
    }
  return f;
  }
}

我正在尝试获取输出:

1! = 1 
2! = 2 
3! = 6 
4! = 24 
5! = 120

但是当我运行代码时，我得到了这个:

0! = 1
1! = 1
2! = 1
3! = 1
4! = 1
5! = 1

我的问题是，如何通过 factorial 静态方法将 for 循环每次迭代的结果返回到 main 方法？

Answer 1

您需要删除 for 循环中的 return f; 语句。 if 中的返回将始终在第一次迭代后立即返回到调用方法。这就是为什么所有阶乘的结果都是 1。

public static int factorial (int n) {
    int f = 1;
    for (int i = 1; i <= n; ++i) {
      f *= i;
      // return f; // Not needed - this is causing the problem
    }
    return f; // This is your required return
}

如 Ravi指出

for (int i = 1; i <= n; ++i) { // well 0 will return 1 as well, so no prob unless you don't need 0 factorial
  System.out.println(i + "! = " + factorial(i)); // you need to pass i instead of n as i is the counter here
}