理解Java中processbuilder的示例代码

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

public class ProcessBuilderExample {
    public static void main(String[] args) {
        try {
            // 创建ProcessBuilder对象，并指定要执行的命令
            ProcessBuilder pb = new ProcessBuilder("ls", "-l");

            // 设置工作目录（可选）
            pb.directory(new File("/path/to/directory"));

            // 启动进程
            Process process = pb.start();

            // 获取进程的输出流
            BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()));

            // 读取输出
            String line;
            while ((line = reader.readLine()) != null) {
                System.out.println(line);
            }

            // 等待进程执行完毕并获取返回值
            int exitCode = process.waitFor();
            System.out.println("Exit Code: " + exitCode);

        } catch (IOException | InterruptedException e) {
            e.printStackTrace();
        }
    }
}