Detailed introduction to Java object serialization

java provides two methods of object persistence: serialization and external serialization

(1) Serialization Serialization

Serialization is a method of converting an object into a string of bytes Describes a process for solving problems caused by reading and writing object streams.

All classes to be serialized must implement the serializable interface

(2) External serialization (externalizable)

To implement external serialization, you need to implement readExternal(ObjectInput in) and writeExternal(ObjectOutput out) method.

Serialization features:

1. If a class can be serialized, its subclasses can also be serialized.

2. Since variables or methods modified with static represent members of the class, and variables modified with the transient keyword represent temporary data of the object, data members declared in these two types cannot be serialized.

When to use serialization?

1. The object needs to be sent over the network or the state of the object needs to be persisted to the database or file

2. Serialization can achieve deep copying.

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