Java serializable implementation

In Java, everyone knows that serializable interfaces must be implemented first for serializable classes. I thought this was so simple,

However, when I wrote a program a few days ago, I found that there is still an article in it. In fact, a class must be serialized, not only must this class implement the serializable interface,

The member attributes in this class must also implement the serializable interface to write the members of this class into the file,

For example:

Class house implements serializable {

Private table;

Private chair;

}

Class table implements serializable {

Private book;

Private pen;

}

Class chair {

....

}

Class pen implements serializable {

.....

}

Class book {

....

}

 

For example, if you assign a value to each class member and write the house class to a file, read the house class and you will find that

The class member that implements the serializable interface (the pen in the table) is the value you write in, but the class member that does not implement the serializable interface (Chair and book in the table) is null.