The function of the transient keyword is: variables modified by transient do not participate in serialization and deserialization. When an object is serialized, the values ??of transient variables are not included in the serialized representation, whereas non-transient variables are included.
The operating environment of this tutorial: windows7 system, java10 version, Dell G3 computer.
(Learning video sharing: java teaching video)
Java's serialization provides a mechanism for persisting object instances. When persisting an object, there may be a special object data member that we don't want to use the serialization mechanism to save.
To turn off serialization on a field of a specific object, you can add the keyword transient before this field.
When an object is serialized, the values ??of transient variables are not included in the serialized representation, while non-transient variables are included.
In short, Variables modified by transient do not participate in serialization and deserialization.
Next, use code to prove it.
Create a new Student class to implement the Serializable interface, and rewrite its toString method to facilitate observation of the results.
An age attribute is not modified by transient, and a name attribute is modified by transient.
public class Student implements Serializable {
private int age;
private transient String name;
public Student() {
}
public Student(int age, String name) {
this.age = age;
this.name = name;
}
@Override
public String toString() {
return "Student{" + "age=" + age + ", name='" + name + '\'' + '}';
}
}Then test it in the TransientTest class.
PS:
For the simplicity of the code, the IO operation here does not perform a try catch operation but is thrown directly.
public class TestTransient {
public static void main(String[] args) throws Exception {
// 實例化一個Student對象.
Student student = new Student(15, "HuaGe");
System.out.println(student);
// 將student對象寫入磁盤文件(序列化)
ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("student.txt"));
oos.writeObject(student);
oos.close();
// 從磁盤文件讀取student對象(反序列化)
ObjectInputStream ois = new ObjectInputStream(new FileInputStream("student.txt"));
student = (Student) ois.readObject();
System.out.println(student);
}
}Run the main method and observe the console printing information.
It was found that after serialization and deserialization, the name attribute changed from HuaGe to null.
This shows that is modified by transient Variables do not participate in serialization and deserialization.
Are there any exceptions?
We know that there are two serialization methods in java.
1. Implement the Serializable interface.
2. Implement the Externalizable interface.
Externalizable interface is a subclass of Serializable interface
The source code is as follows
public interface Externalizable extends java.io.Serializable {
void writeExternal(ObjectOutput out) throws IOException;
void readExternal(ObjectInput in) throws IOException, ClassNotFoundException;
}The two methods of this interface can specify which attributes in the class are serialized.
When using this interface, no matter whether the properties are modified by transient or not,
no properties will be serialized by default. Therefore, classes that implement the Externalizable interface
generally no longer use transient modified attributes.
Summary:
1. Variables modified by transient do not participate in serialization and deserialization
#2. Transient is generally used in classes that implement the Serializable interface.
For more programming-related knowledge, please visit: Programming Teaching! !
The above is the detailed content of What is the role of transient keyword. For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undress AI Tool
Undress images for free
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
VSCode settings.json location
Aug 01, 2025 am 06:12 AM
The settings.json file is located in the user-level or workspace-level path and is used to customize VSCode settings. 1. User-level path: Windows is C:\Users\\AppData\Roaming\Code\User\settings.json, macOS is /Users//Library/ApplicationSupport/Code/User/settings.json, Linux is /home//.config/Code/User/settings.json; 2. Workspace-level path: .vscode/settings in the project root directory
How to handle transactions in Java with JDBC?
Aug 02, 2025 pm 12:29 PM
To correctly handle JDBC transactions, you must first turn off the automatic commit mode, then perform multiple operations, and finally commit or rollback according to the results; 1. Call conn.setAutoCommit(false) to start the transaction; 2. Execute multiple SQL operations, such as INSERT and UPDATE; 3. Call conn.commit() if all operations are successful, and call conn.rollback() if an exception occurs to ensure data consistency; at the same time, try-with-resources should be used to manage resources, properly handle exceptions and close connections to avoid connection leakage; in addition, it is recommended to use connection pools and set save points to achieve partial rollback, and keep transactions as short as possible to improve performance.
python itertools combinations example
Jul 31, 2025 am 09:53 AM
itertools.combinations is used to generate all non-repetitive combinations (order irrelevant) that selects a specified number of elements from the iterable object. Its usage includes: 1. Select 2 element combinations from the list, such as ('A','B'), ('A','C'), etc., to avoid repeated order; 2. Take 3 character combinations of strings, such as "abc" and "abd", which are suitable for subsequence generation; 3. Find the combinations where the sum of two numbers is equal to the target value, such as 1 5=6, simplify the double loop logic; the difference between combinations and arrangement lies in whether the order is important, combinations regard AB and BA as the same, while permutations are regarded as different;
Mastering Dependency Injection in Java with Spring and Guice
Aug 01, 2025 am 05:53 AM
DependencyInjection(DI)isadesignpatternwhereobjectsreceivedependenciesexternally,promotingloosecouplingandeasiertestingthroughconstructor,setter,orfieldinjection.2.SpringFrameworkusesannotationslike@Component,@Service,and@AutowiredwithJava-basedconfi
python pytest fixture example
Jul 31, 2025 am 09:35 AM
fixture is a function used to provide preset environment or data for tests. 1. Use the @pytest.fixture decorator to define fixture; 2. Inject fixture in parameter form in the test function; 3. Execute setup before yield, and then teardown; 4. Control scope through scope parameters, such as function, module, etc.; 5. Place the shared fixture in conftest.py to achieve cross-file sharing, thereby improving the maintainability and reusability of tests.
Troubleshooting Common Java `OutOfMemoryError` Scenarios
Jul 31, 2025 am 09:07 AM
java.lang.OutOfMemoryError: Javaheapspace indicates insufficient heap memory, and needs to check the processing of large objects, memory leaks and heap settings, and locate and optimize the code through the heap dump analysis tool; 2. Metaspace errors are common in dynamic class generation or hot deployment due to excessive class metadata, and MaxMetaspaceSize should be restricted and class loading should be optimized; 3. Unabletocreatenewnativethread due to exhausting system thread resources, it is necessary to check the number of threads, use thread pools, and adjust the stack size; 4. GCoverheadlimitexceeded means that GC is frequent but has less recycling, and GC logs should be analyzed and optimized.
How to work with Calendar in Java?
Aug 02, 2025 am 02:38 AM
Use classes in the java.time package to replace the old Date and Calendar classes; 2. Get the current date and time through LocalDate, LocalDateTime and LocalTime; 3. Create a specific date and time using the of() method; 4. Use the plus/minus method to immutably increase and decrease the time; 5. Use ZonedDateTime and ZoneId to process the time zone; 6. Format and parse date strings through DateTimeFormatter; 7. Use Instant to be compatible with the old date types when necessary; date processing in modern Java should give priority to using java.timeAPI, which provides clear, immutable and linear
Advanced Spring Data JPA for Java Developers
Jul 31, 2025 am 07:54 AM
The core of mastering Advanced SpringDataJPA is to select the appropriate data access method based on the scenario and ensure performance and maintainability. 1. In custom query, @Query supports JPQL and native SQL, which is suitable for complex association and aggregation operations. It is recommended to use DTO or interface projection to perform type-safe mapping to avoid maintenance problems caused by using Object[]. 2. The paging operation needs to be implemented in combination with Pageable, but beware of N 1 query problems. You can preload the associated data through JOINFETCH or use projection to reduce entity loading, thereby improving performance. 3. For multi-condition dynamic queries, JpaSpecifica should be used
