求助Java这个题目，求源码⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯

Question

⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯

Answer 1

/**

• MathCal *
• @author littlehow

• @time 2016-11-15 15:37
  */
  public class MathCal {
  public static void main(String[] args) {
  try {
  if(args.length == 0) throw new ArrayIndexOutOfBoundsException("命令行中没有提供参数");
  String target = args[0];
  try{
  int targetNumber = Integer.parseInt(target);
  System.out.println(getJieCheng(targetNumber));
  }catch (NumberFormatException e) {
  //这里没有判断是否输入为数字，所以直接捕获异常，正常程序是需要判定的，一面增加错误堆栈
  throw new IllegalArgumentException(e.getMessage());
  }
  } finally {
  System.out.println("程序运行结束!");
  }
  }

  /**

  • 求阶乘
  • @param number
  • @return */ public static int getJieCheng(int number) { if(number < 0) throw new IllegalArgumentException("求负数阶乘异常!"); if(number == 0 || number == 1) return 1; return number * getJieCheng(number - 1); } }

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