System.in上的Java BufferedReader忽略第一行/命令

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        
        // 读取第一行或命令
        String firstLine = reader.readLine();
        
        // 逐行读取并处理数据
        String line;
        while ((line = reader.readLine()) != null) {
            // 在这里处理每一行数据
            System.out.println(line);
        }
        
        reader.close();
    }
}