When an object is serialized, according to Java's default serialization rules, all members in the object must be serialized. That is to say, these Classes must implement Serializable.

So, you have two ways to modify it. One is to implement the Serializable interface in Address, and the other is to add thetransientmark to the address member in Person so that the member will not be serialized.

If the address member needs to be serialized, the Address class also needs to implement theSerializableinterface.
If the address member does not need to be serialized, you can add thetransientkeyword, then the address member will not be serialized and the value will be null. As follows:

public class Person implements Serializable { private static final long serialVersionUID = 1905122041950251207L; private String name; private transient Address address; // Noncompliant; Address isn't serializable }

Of course there are other ways:
For example, implementing theExternalizableinterface and overriding the readExternal(ObjectInput in) and writeExternal(ObjectOutput out) methods.
There is also an alternative implementation of theExternalizableinterface method, or implement theSerializableinterface, adding writeObject(ObjectOutputStream obs) and readObject(ObjectInputStream ois) methods.

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Tell me again why Address must implementSerializable, or add thetransientkeywordPersonin order to be serialized?
Let’s first take a look at the exception thrown by usingObjectOutputStreamto persist the object without processing

Exception in thread "main" java.io.NotSerializableException

Look atObjectOutputStreamSource code:

/** * Underlying writeObject/writeUnshared implementation. */ private void writeObject0(Object obj, boolean unshared) throws IOException { //...... // remaining cases if (obj instanceof String) { writeString((String) obj, unshared); } else if (cl.isArray()) { writeArray(obj, desc, unshared); } else if (obj instanceof Enum) { writeEnum((Enum) obj, desc, unshared); } else if (obj instanceof Serializable) { writeOrdinaryObject(obj, desc, unshared); } else { if (extendedDebugInfo) { throw new NotSerializableException( cl.getName() + "\n" + debugInfoStack.toString()); } else { throw new NotSerializableException(cl.getName()); } } } finally { depth--; bout.setBlockDataMode(oldMode); } }

It can be seen from this that if the object type being written is String, Array, Enum, or Serializable, it can be serialized, otherwise NotSerializableException will be thrown. And when serializing an object, not only the current object itself will be serialized, but other objects referenced by the object will also be serialized.