为何写入对象不能正确显示，运行时出 现Exception in thread "main" java.io.EOFException。程序如下

[junzhangdemingzi]

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;


public class ass {
private record rd;
ObjectOutputStream output;
ObjectInputStream input;
/**
* @param args
* @throws IOException
* @throws FileNotFoundException
public ass()
* {
* }
*/
public ass()
{try{
rd=new record();
output=new ObjectOutputStream(new FileOutputStream("e:\\file.txt"));
input=new ObjectInputStream(new FileInputStream("e:\\file.txt"));}
catch(Exception er){}
}
public void setrecord()
{rd.setaccount(200);
rd.setname("nihao");
rd.setpayment(20);
rd.setprice(30);}
public void write(record rd)throws Exception
{output.writeObject(rd);output.close();
}
public record read()throws Exception
{record d=(record)input.readObject();
input.close();
return d;}

public static void main(String[] args) throws Exception
{ass d=new ass();
d.setrecord();
System.out.println(d.read());

}
private class record implements Serializable
{private int account;
private String name;
private float price;
private float payment;
public record()
{}
public record(int account,String name,float price,float payment)
{this.account=account;
this.name=name;
this.payment=payment;
this.price=price;

}
public void setaccount(int acc)
{account=acc;}
public int getaccount()
{return account;}

public void setname(String na)
{name=na;}
public String getname()
{return name;}

public void setprice(float pri)
{price=pri;}
public float getprice()
{return price;}

public void setpayment(float pay)
{payment=pay;}
public float getpayment()
{return payment;}

}
// 销售记录类结束


}
运行后抛出异常如下

Exception in thread "main" java.io.EOFException
at java.io.ObjectInputStream$BlockDataInputStream.peekByte(ObjectInputStream.java:2502)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1267)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:339)
at ass.read(ass.java:38)
at ass.main(ass.java:44)

[chosen0ne]

ObjectOutputStream每次在写完对象时，需要flush（）一下，因为只是将内容写到缓存中，flush之后写入文件。

public void write(record rd)throws Exception 
{
    output.writeObject(rd);
    output.flush(); ///加上这句
    output.close(); 
} 

[junzhangdemingzi]

谢谢，但还是不行

[chosen0ne]

哦！下午时没仔细看。
1.你没有调用write（）方法，所以没有写入文件，则调用read（）时文件为空，所以返回EOFException。
2.将类序列化时，该类不能是内部类，所以需要把record放到ass类外面。

import java.io.*;
import java.io.Serializable; 


public class ass { 
	private record rd; 
	ObjectOutputStream output; 
	ObjectInputStream input; 
        
	public ass() 
	{
                try{ 
                    rd=new record();
                    output=new ObjectOutputStream(new FileOutputStream("e:\\file.txt")); 
                    input=new ObjectInputStream(new FileInputStream("e:\\file.txt"));
                } 
                catch(Exception er){
                } 
	} 
	public void setrecord() 
	{
		rd.setaccount(200); 
		rd.setname("nihao"); 
		rd.setpayment(20); 
		rd.setprice(30);
                write(rd);////调用write()
	} 
	public void write(record rd)
	{
		try{
			output.writeObject(rd);
			output.flush();
			output.close();
		}
		catch(Exception e){
			e.printStackTrace();
		}
	} 
	public record read() 
	{
		record d=null;
		try{
			d=(record)input.readObject(); 
			input.close();
		}
		catch(Exception e){
			e.printStackTrace();
		}
		return d;
	} 

	public static void main(String[] args) 
	{
		ass d=new ass(); 
		d.setrecord(); 
		System.out.println(d.read()); 

	} 

	
}

class record implements Serializable 
{
	private int account; 
	private String name; 
	private float price; 
	private float payment; 
        public record(){}
        public record(int account,String name,float price,float payment) 
	{
            this.account=account; 
            this.name=name; 
            this.payment=payment; 
            this.price=price; 
	} 
	public void setaccount(int acc) 
	{
            account=acc;
	} 
	public int getaccount() 
	{
            return account;
	} 
  
	public void setname(String na) 
	{
            name=na;
	} 
	public String getname() 
	{	
            return name;
	} 
  
	public void setprice(float pri) 
	{
            price=pri;
	} 
	public float getprice() 
	{
            return price;
	} 
  
	public void setpayment(float pay) 
	{
            payment=pay;
	} 
	public float getpayment() 
	{
            return payment;
	} 

} 

[铁匠梁老师]

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;

public class ass{
	
	private static record rd;
	ObjectOutputStream output;
	ObjectInputStream input;

	
	public ass() {		
	}
	
	//设置记录的属性值
	public void setrecord() {
		rd = new record();
		rd.setaccount(200);
		rd.setname("nihao");
		rd.setpayment(20);
		rd.setprice(30);		
	}
	
	//写入文件
	public void write(record rd) throws Exception {
		output=new ObjectOutputStream(new FileOutputStream("e:\\file.txt"));
		output.writeObject(rd);
		output.flush();
		output.close();
	}
	
	//从文件中读取出来
	public record read() throws Exception {
		input=new ObjectInputStream(new FileInputStream("e:\\file.txt"));
		record d = (record) input.readObject();
		input.close();
		System.out.println(d.getname());
		System.out.println(d.getprice());
		System.out.println(d.getaccount());
		System.out.println(d.getpayment());
		return d;
	}

	public static void main(String[] args) throws Exception {
		//流程先要理清：先生成文件，然后再去文件读取出来。
		ass d = new ass();
		d.setrecord();
		d.write(rd);
		d.read();
	}
}

/**
 * 
 * 对象实体不能是内部类
 * @author foolishdault
 *
 */
class record implements Serializable {
	
	private static final long serialVersionUID = 3L;//序列化值，写文件或者网络传输都必须设置这个值
			
	private int account;
	private String name;
	private float price;
	private float payment;

	public record() {
	}

	public record(int account, String name, float price, float payment) {
		this.account = account;
		this.name = name;
		this.payment = payment;
		this.price = price;

	}

	public void setaccount(int acc) {
		account = acc;
	}

	public int getaccount() {
		return account;
	}

	public void setname(String na) {
		name = na;
	}

	public String getname() {
		return name;
	}

	public void setprice(float pri) {
		price = pri;
	}

	public float getprice() {
		return price;
	}

	public void setpayment(float pay) {
		payment = pay;
	}

	public float getpayment() {
		return payment;
	}
}

[junzhangdemingzi]

谢谢，谢谢各位，真的可以了。真是：听君一席话，胜读十年书