使用ProcessBuilder运行外部Java进程，并给出堆大小

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

public class ExternalProcessExample {
    public static void main(String[] args) {
        try {
            // 创建ProcessBuilder对象，并指定要执行的命令
            ProcessBuilder processBuilder = new ProcessBuilder("java", "-Xmx512m", "MyExternalClass");

            // 启动外部进程
            Process process = processBuilder.start();

            // 获取进程的输入流
            InputStream inputStream = process.getInputStream();
            BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));

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

            // 等待外部进程执行完毕
            int exitCode = process.waitFor();
            System.out.println("External process exited with code " + exitCode);

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