为什么我的if语句总是返回false？ （返回值始终为0）

Question

功能＆＃39; spd＆＃39;用于查找整数y的最小素数。 但是，当我运行代码时，无论＆＃39; y＆＃39;是，返回值始终为0.

public static BigInteger spd (int y) {

    ArrayList<BigInteger> primes = new ArrayList<BigInteger>();

    int retval;
    int Nth_prime = 10000;
    BigInteger getn;
    BigInteger y2 = BigInteger.valueOf(y);
    BigInteger TWO = new BigInteger("2");
    BigInteger bi = new BigInteger("1");

    primes.add(TWO);

    int i = 1;

    while (i < Nth_prime) {
        bi = bi.add(TWO);
        if (bi.isProbablePrime(40)) {
            i++;
            primes.add(bi);
        }
    }

    BigInteger zero = new BigInteger ("0");
    BigInteger ret;
    BigInteger one  = new BigInteger ("1");

    for (int n = 0; n < y2.intValue(); n++) {
        if (y2.mod(primes.get(n)).equals(zero)) {
            retval = primes.get(n).intValue();
        }
    }   

    BigInteger returning = BigInteger.valueOf(retval);

    return returning;
}

Answer 1

这是初始化代码和一些重构代码：

 class example {
 private $something = "something";
 public function myFunction($a = null) 
 {
    if($a === null) 
       $a = $this->something; 
     // more code goes here
    return $a; 
  }
 }
 $test = new example();
 print $test->myFunction();
 // prints "something"
 print $test->myFunction("hello");
 // prints "hello"