Java 如何通过DataOutputStream发送算术运算的有效结果

我有一个子流程类，它计算两个整数的和，然后将其放入DataOutputStream：

public class SubProcess {
  public static void main(String[] args) throws IOException {
     DataInputStream in = new DataInputStream(System.in);
     DataOutputStream out = new DataOutputStream(System.out);
     int a = in.readInt();
     out.writeInt(a);
     int b = in.readInt();
     out.writeInt(b);
     int result = a+b;
     out.writeInt(result);
     out.flush();
     in.read();
     out.close();
     in.close();
    }
  } 

当分别写入a和b的两个值（如12和47）时，结果为“ei”

另一方面，mainprocess不会像通过ReadInt（）行读取DataInputStream那样读取该结果，它会抛出一个异常：

        Exception in thread "main" java.io.EOFException
            at java.io.DataInputStream.readInt(Unknown Source)
            at testthread.MainProcess.main(MainProcess.java:21)

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似乎主进程并没有真正与子进程通信。从两个类中删除包并在cmd上运行主进程可以避免异常