Serialization

Code

import java.io.*;

class User implements Serializable {
    private static final long serialVersionUID = 1L;
    private String name;
    private transient String password; // Not serialized

    public User(String name, String password) {
        this.name = name;
        this.password = password;
    }
}

// Serialize
try (ObjectOutputStream oos = new ObjectOutputStream(
        new FileOutputStream("user.dat"))) {
    oos.writeObject(new User("Alice", "secret"));
}

// Deserialize
try (ObjectInputStream ois = new ObjectInputStream(
        new FileInputStream("user.dat"))) {
    User user = (User) ois.readObject();
    System.out.println(user.name); // Alice
    // password is null (transient)
}

Explanation

The Serializable interface marks serializable classes; transient fields are excluded from serialization.

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