What does the transient keyword in java do?
Nov 26, 2019 am 10:30 AM
Function:
When serializing data, if you don’t want to serialize one of the attributes into a file, you need to use transient Modification, indicating that the attribute is a temporary attribute
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This is a student class:
public class Student implements Serializable {//注意：要想序列化，必須實(shí)現(xiàn)Serializable接口
private String name;
private Integer age;
private transient String address; //使用transient修飾
public Student() {
}
public Student(String name, Integer age, String address) {
this.name = name;
this.age = age;
this.address = address;
}
//Getter/Setter
} When I serialize, I don’t plan to save the student’s address attribute. I only want to save the name and age attributes. I modify the adress attribute with the transient keyword and serialize it as follows:
public class TestStudent {
public static void main(String[] args) throws IOException {
List<Student> list = new ArrayList<>();
Student s1 = new Student("Jack", 20, "北京");
Student s2 = new Student("Rose", 21, "上海");
Student s3 = new Student("Hoke", 22, "深圳");
Student s4 = new Student("Mark", 23, "天津");
Student s5 = new Student("Json", 24, "成都");
list.add(s1);
list.add(s2);
list.add(s3);
list.add(s4);
list.add(s5);
//將學(xué)生信息序列化到student.txt文件中
File file = new File("student.txt");
ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(file));
oos.writeObject(list);
}
}Proceed below Deserialize and verify the role of transient:
@Test
public void test() throws IOException, ClassNotFoundException {
ObjectInputStream ois = new ObjectInputStream(new FileInputStream(new File("student.txt")));
Object object = ois.readObject();
if (object instanceof List) {
List<Student> list = (List<Student>) object;
list.forEach(System.out::println);
}
} Result:
You can see that the address attribute value in the output result is null. The value is not serialized;
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