largestprime.java

Java程序设计技巧与开发实例附书源代码。

public class LargestPrime
{  public static void main(String args[])
   {  long primeCandidate = 9223372036854775807L;  
      boolean foundPrime = false;
      while (!foundPrime )
      {  long divider = 2;
         boolean foundDivider = (primeCandidate % divider) == 0;
         divider = 3;
         while ((!foundDivider) && (divider <= Math.sqrt(primeCandidate)))
         {  foundDivider = (primeCandidate % divider) == 0;
            divider += 2;
         }
         if (foundDivider)
            System.out.println(primeCandidate + "不是一个素数");
         else
            System.out.println(primeCandidate + "是一个素数");
         foundPrime = !foundDivider;
         primeCandidate--;
      }
   }
}