如何在SpannableString中查找子字符串的索引

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

public class Main {
    public static void main(String[] args) {
        String text = "This is a sample text.";
        String substring = "sample";
        
        // 创建Pattern对象
        Pattern pattern = Pattern.compile(substring);
        
        // 在文本中查找匹配的子字符串
        Matcher matcher = pattern.matcher(text);
        
        // 查找并输出子字符串的索引
        while (matcher.find()) {
            int start = matcher.start();
            int end = matcher.end();
            System.out.println("Substring '" + substring + "' found at index " + start + " - " + (end - 1));
        }
    }
}

Substring 'sample' found at index 10 - 15