Java堆栈溢出错误

我正在尝试编写一个GCD算法，除了StackOverflower错误外，其他一切似乎都是正确的。代码如下：

public class Gcd {
    public static BigInteger gcdNaive(BigInteger a, BigInteger b) {
        int res = a.compareTo(b);

        if ( res == 0 ) {
            BigInteger g = a;
            return g;
        }
        else if ( res == 1 ) {
            BigInteger h = a.subtract(b);
            a = h;
            return gcdNaive(a, b);
        }
        else if ( res == -1 ) {
            BigInteger g = b.subtract(a);
            b = g;
            return gcdNaive(a, b);
        }

        return BigInteger.ZERO;
    }

    public static BigInteger gcdEuclid(BigInteger a, BigInteger b) {
        if( b == BigInteger.ZERO ) {
            BigInteger g = a;
            return g;
        }
        else if ( b != BigInteger.ZERO ) {
            BigInteger g = b;
            BigInteger h = a.mod(b);
            a = g;
            b = h;
            return gcdEuclid(a, b);
        }

        return BigInteger.ZERO;
    }
}

例外情况：

Exception in thread "main" java.lang.StackOverflowError 


    at Gcd.gcdNaive(Gcd.java:7) 
    at Gcd.gcdNaive(Gcd.java:19)

---

gcdNaive的解决方案是：

public static BigInteger gcdNaive(BigInteger a, BigInteger b) {
    int res = a.compareTo(b);

    if(res == 0)
    {
        return b;
    }

    if(res == 1)
    {
        a = a.subtract(b);
        return gcdNaive(a, b);
    }
    else
    {
        b = b.subtract(a);
        return gcdNaive(a, b);
    }
}

gcdEuclid的完整解决方案是

public static BigInteger gcdEuclid(BigInteger a, BigInteger b) {

    if(b == BigInteger.ZERO)
    {
        return a;
    }

    return gcdEuclid(b, a.mod(b));
}

---

什么输入会产生错误？第二个函数的全部可以替换为

return b==biginger.ZERO？a:gcdEuclid（b，a.mod（b））您正在从不应该到达的路径返回值，并使您的代码不必要地难以使用所有这些临时变量。那么，您是否在调试器中逐步完成了代码？