如何提取位于给定字符之前的字符串前缀？

def extract_prefix(string, delimiter):
    index = string.find(delimiter)
    if index != -1:
        return string[:index]
    else:
        return string

# 示例用法
string = "Hello, World!"
delimiter = ","
prefix = extract_prefix(string, delimiter)
print(prefix)

public class StringPrefixExtractor {
    public static String extractPrefix(String string, String delimiter) {
        int index = string.indexOf(delimiter);
        if (index != -1) {
            return string.substring(0, index);
        } else {
            return string;
        }
    }

    // 示例用法
    public static void main(String[] args) {
        String string = "Hello, World!";
        String delimiter = ",";
        String prefix = extractPrefix(string, delimiter);
        System.out.println(prefix);
    }
}