为什么会报错呢？

# 

System.out.println(ois.readInt());

把这条语句注释后就会报错，这是为什么啊？

# 报错信息的截图

import java.io.*;

public class Product implements Serializable {
    private String id;
    private String name;
    private String categories;
    private Float price;

    public Product(){

    }

    public Product(String id, String name, String categories, Float price) {
        this.id = id;
        this.name = name;
        this.categories = categories;
        this.price = price;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getCategories() {
        return categories;
    }

    public void setCategories(String categories) {
        this.categories = categories;
    }

    public Float getPrice() {
        return price;
    }

    public void setPrice(Float price) {
        this.price = price;
    }

    @Override
    public String toString() {
        return "Product{" +
                "id='" + id + '\'' +
                ", name='" + name + '\'' +
                ", categories='" + categories + '\'' +
                ", price=" + price +
                '}';
    }

    public static void main(String[] args) {
        Product product = new Product("256", "iwatch", "watch", 4799f);
        try {
            FileOutputStream fos = new FileOutputStream("C:\\Users\\wmj\\Desktop\\test\\1\\1.txt");
            FileInputStream fis = new FileInputStream("C:\\Users\\wmj\\Desktop\\test\\1\\1.txt");
            ObjectOutputStream oos = new ObjectOutputStream(fos);
            ObjectInputStream ois = new ObjectInputStream(fis);
            oos.writeInt(123);
            oos.writeObject(product);

            oos.flush();
         //   System.out.println(ois.readInt());
            Product product1=(Product)ois.readObject();
            System.out.println(product1);
            ois.close();
            oos.close();
            fis.close();
            fos.close();

        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }
}

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