计算926的9260次方里的字符串里有多少个926

package StringTest;

import java.math.BigDecimal;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import static java.lang.Math.pow;

public class String10 {
    
    public static void main(String[] args) {
    
        double a = pow(12, 2);
        System.out.println("a = " + a);

        //926的9260次方里的字符串里有多少个926
        String sub = "926";
        BigDecimal bigDecimal = new BigDecimal(926);
        BigDecimal pow = bigDecimal.pow(9260);
        String string = pow.toString();
        System.out.println("string长度为 " + string.length());

        int count1 = countSub1(string, sub);
        System.out.println("count1 = " + count1);
        System.out.println();
        
        int count2 = countSub2(string, sub);
        System.out.println("count2 = " + count2);
    }

    private static int countSub1(String string, String sub) {
    
        int count = 0;
        long begin = System.currentTimeMillis();
        Matcher matcher = Pattern.compile(sub).matcher(string);
        while (matcher.find()) {
    
            count++;
        }
        long end = System.currentTimeMillis();
        System.out.println("运行时间1 = " + (double) (end - begin) / 1000);
        return count;
    }

    private static int countSub2(String string, String sub) {
    
        int olcCount = string.length();
        long begin = System.currentTimeMillis();
        int newCount = string.replace(sub, "").length();
        int count = (olcCount - newCount) / sub.length();
        long end = System.currentTimeMillis();
        System.out.println("运行时间2 = " + (double) (end - begin) / 1000);
        return count;
    }
}