一个家庭两个孩子，已知一个是女孩，另一个是女孩的概率是？Java

package helloworld;
import java.util.Random;
public class hello {
        public static void main(String[] args) {
            for(int i = 0; i < n; ++i){
                Random x1 = new Random();
                Random x2 = new Random();
                int r1 = x1.nextInt(2);
                int r2 = x2.nextInt(2);
                if(r1 == girl && r2 == girl) g2++;
                if(r1 == girl || r2 == girl) g1++;
            }
            System.out.println(g2 * 1.0 / g1);
        } 
        static int girl = 0, boy = 1;
        static int g1 = 0;
        static int g2 = 0;
        static int n = 10000;
}