Question

//在运行Aamir课程时，我收到此错误。

import java.io.Externalizable;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectInputStream;
import java.io.ObjectOutput;
import java.io.ObjectOutputStream;

public class Aamir {

    public static void main(String[] args)  throws Exception {


        Externalize();
        deExternalize();    
    }

  public static void Externalize() throws IOException {


    Person p1 = new Person();
    p1.name = "aamir";
    p1.age = 22;
    p1.weight = 60.80;

    Person p2 = new Person();
    p2.name = "zahid";
    p2.age = 26;
    p2.weight = 64.88;

    FileOutputStream fout = new FileOutputStream("dev.txt");
    ObjectOutputStream out = new ObjectOutputStream(fout);

    p1.writeExternal(out);
    p2.writeExternal(out);

    out.flush();        
    out.close();
}

    public static void deExternalize() throws IOException, ClassNotFoundException {

        FileInputStream fin = new FileInputStream("dev.ser");
        ObjectInputStream in = new ObjectInputStream(fin);

        Person p3 = new Person();
        p3.readExternal(in);

        Person p4 = new Person();
        p4.readExternal(in);
   }
}

class Person implements Externalizable  {

    String name;
    int age;
    double weight;

  public void writeExternal(ObjectOutput out) throws IOException {

    out.writeUTF(name);
    out.writeInt(age);
    out.writeDouble(weight);
     out.flush();
     out.close();
  }

  public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {


    name = in.readUTF();
    age = in.readInt();
    weight = in.readDouble();

    System.out.println(name);
    System.out.println(age);
    System.out.println(weight);


}

}

Answer 1

您收到错误是因为您在关闭它后尝试写入流。

您不需要在writeExternal中刷新或关闭流。

Answer 2

您.close()中的.writeExternal()个流;你不应该。

Externalizable的合同中从未说过这种方法应该关闭流;怎么一个类继承你并调用super.writeExternal（）？

Answer 3

您尝试关闭ObjectOutputStream两次。

in：

    FileOutputStream fout = new FileOutputStream("dev.txt");
ObjectOutputStream out = new ObjectOutputStream(fout);

p1.writeExternal(out);
p2.writeExternal(out);

out.flush();        
out.close(); <-----

在这里：

public void writeExternal(ObjectOutput out) throws IOException {

out.writeUTF(name);
out.writeInt(age);
out.writeDouble(weight);
 out.flush();
 out.close(); <-----

你不应该在writeExternal中关闭它。

Answer 4

您获得运行时异常的原因是因为您关闭了ObjectOutputStream资源，但是再次通过该“out”引用尝试编写p2数据。所以这是正确的代码

import java.io.Externalizable;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectInputStream;
import java.io.ObjectOutput;
import java.io.ObjectOutputStream;

class Aamir {

    public static void main(String[] args)  throws Exception {


        Externalize();
        deExternalize();    
    }

  public static void Externalize() throws IOException {


    Person p1 = new Person();
    p1.name = "aamir";
    p1.age = 22;
    p1.weight = 60.80;

    Person p2 = new Person();
    p2.name = "zahid";
    p2.age = 26;
    p2.weight = 64.88;

    FileOutputStream fout = new FileOutputStream("dev.txt");
    ObjectOutputStream out = new ObjectOutputStream(fout);

    p1.writeExternal(out);
    p2.writeExternal(out);

    out.flush();        
   out.close();
}

    public static void deExternalize() throws IOException, ClassNotFoundException {

        FileInputStream fin = new FileInputStream("dev.ser");
        ObjectInputStream in = new ObjectInputStream(fin);

        Person p3 = new Person();
        p3.readExternal(in);

        Person p4 = new Person();
        p4.readExternal(in);
   }
}

class Person implements Externalizable  {

    String name;
    int age;
    double weight;

  public void writeExternal(ObjectOutput out) throws IOException {

    out.writeUTF(name);
    out.writeInt(age);
    out.writeDouble(weight);
    // out.flush();
     //out.close();
  }

  public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {


    name = in.readUTF();
    age = in.readInt();
    weight = in.readDouble();

    System.out.println(name);
    System.out.println(age);
    System.out.println(weight);


}
}

流关闭：运行时错误消息

4 个答案: